Filters take in an image representation of an entity, Group of entitys or a Cell display and, by manipulating the image’s data, return an updated image which replaces those entitys or Cell in the final output display.
Scrawl-canvas defines its filters in Filter objects, detailed in this module. The functionality to make use of these objects is coded up in the filter mixin, which is used by the Cell, Group and all entity factories.
The Scrawl-canvas filter engine implements a number of common filter algorithms. These algorithms - called filter actions - can be combined in a wide variety of ways, including the use of multiple pathways, to create complex filter results.
alpha-to-channels - Copies the alpha channel value over to the selected value or, alternatively, sets that channels value to zero, or leaves the channel’s value unchanged. Setting the appropriate “includeChannel” flags will copy the alpha channel value to that channel; when that flag is false, setting the appropriate “excludeChannel” flag will set that channel’s value to zero. Object attributes: action, lineIn, lineOut, opacity, includeRed, includeGreen, includeBlue, excludeRed, excludeGreen, excludeBlue.
area-alpha - Places a tile schema across the input, quarters each tile and then sets the alpha channels of the pixels in selected quarters of each tile to values set in the areaAlphaLevels array. Can be used to create horizontal or vertical bars, or chequerboard effects. Object attributes: action, lineIn, lineOut, opacity, tileWidth, tileHeight, offsetX, offsetY, gutterWidth, gutterHeight, areaAlphaLevels.
average-channels - Calculates an average value from each pixel’s included channels and applies that value to all channels that have not been specifically excluded; excluded channels have their values set to 0. Object attributes: action, lineIn, lineOut, opacity, includeRed, includeGreen, includeBlue, excludeRed, excludeGreen, excludeBlue.
binary - DEPRECATED - functionality moved over to threshold.
blend - Using two source images (from the “lineIn” and “lineMix” arguments), combine their color information using various separable and non-separable blend modes (as defined by the W3C Compositing and Blending Level 1 recommendations). The blending method is determined by the String value supplied in the blend argument; permitted values are: ‘color-burn’, ‘color-dodge’, ‘darken’, ‘difference’, ‘exclusion’, ‘hard-light’, ‘lighten’, ‘lighter’, ‘multiply’, ‘overlay’, ‘screen’, ‘soft-light’, ‘color’, ‘hue’, ‘luminosity’, and ‘saturation’. Note that the source images may be of different sizes: the output (lineOut) image size will be the same as the source (NOT lineIn) image; the lineMix image can be moved relative to the lineIn image using the “offsetX” and “offsetY” arguments. Object attributes: action, lineIn, lineOut, lineMix, opacity, blend, offsetX, offsetY.
blur - Performs a multi-loop, two-step ‘horizontal-then-vertical averaging sweep’ calculation across all pixels to create a blur effect. Note that this filter is expensive, thus much slower to complete compared to other filter effects. Object attributes: action, lineIn, lineOut, opacity, radius, passes, processVertical, processHorizontal, includeRed, includeGreen, includeBlue, includeAlpha, step.
channels-to-alpha - Calculates an average value from each pixel’s included channels and applies that value to the alpha channel. Object attributes: action, lineIn, lineOut, opacity, includeRed, includeGreen, includeBlue.
chroma - A chroma-key effect. Using an array of ‘range’ color arrays, determine whether a pixel’s values lie entirely within a range’s values and, if true, sets that pixel’s alpha channel value to zero. Each ‘range’ color array comprises six Numbers representing [minimum-red, minimum-green, minimum-blue, maximum-red, maximum-green, maximum-blue] values. Object attributes: action, lineIn, lineOut, opacity, ranges.
clamp-channels - Clamp each color channel to a range set by lowColor and highColor values. Object attributes: action, lineIn, lineOut, opacity, lowRed, lowGreen, lowBlue, highRed, highGreen, highBlue.
colors-to-alpha - A chroma-key effect. Determine the alpha channel value for each pixel depending on the closeness to that pixel’s color channel values to a reference color supplied in the “red”, “green” and “blue” arguments. The sensitivity of the effect can be manipulated using the “transparentAt” and “opaqueAt” values, both of which lie in the range 0-1. Object attributes: action, lineIn, lineOut, opacity, red, green, blue, opaqueAt, transparentAt; pseudo-arguments for the convenience method include reference - any valid CSS color string from which the channel values will be calculated.
compose - Using two source images (from the “lineIn” and “lineMix” arguments), combine their color information using alpha compositing rules (as defined by Porter/Duff). The compositing method is determined by the String value supplied in the “compose” argument; permitted values are: ‘destination-only’, ‘destination-over’, ‘destination-in’, ‘destination-out’, ‘destination-atop’, ‘source-only’, ‘source-over’ (default), ‘source-in’, ‘source-out’, ‘source-atop’, ‘clear’, ‘xor’, or ‘lighter’. Note that the source images may be of different sizes: the output (lineOut) image size will be the same as the source (NOT lineIn) image; the lineMix image can be moved relative to the lineIn image using the “offsetX” and “offsetY” arguments. Object attributes: action, lineIn, lineOut, lineMix, opacity, compose, offsetX, offsetY.
corrode - Performs a special form of matrix operation on each pixel’s color and alpha channels, calculating the new value using neighbouring pixel values. Note that this filter is expensive, thus much slower to complete compared to other filter effects. The matrix dimensions can be set using the “width” and “height” arguments, while setting the home pixel’s position within the matrix can be set using the “offsetX” and “offsetY” arguments. The operation will set the pixel’s channel value to match either the ‘lowest’, ‘highest’ or ‘average’ (default) values as dictated by its neighbours - this value is set in the “level” attribute. Channels can be selected by setting the “includeRed”, “includeGreen”, “includeBlue” (all false by default) and “includeAlpha” (default: true) flags. Object attributes: action, lineIn, lineOut, opacity, includeRed, includeGreen, includeBlue, includeAlpha, width, height, offsetX, offsetY, operation.
displace - Shift pixels around the image, based on the values supplied in a displacement process-image. Common source images can be generated from the various Noise assets, though any image will create an effect. Object attributes: action, lineIn, lineOut, lineMix, opacity, channelX, channelY, scaleX, scaleY, transparentEdges, offsetX, offsetY.
emboss - A 3x3 matrix transform; the matrix weights are calculated internally from the values of two arguments: “strength”, and “angle” - which is a value measured in degrees, with 0 degrees pointing to the right of the origin (along the positive x axis). Post-processing options include removing unchanged pixels, or setting then to mid-gray. The convenience method includes additional arguments which will add a choice of grayscale, then channel clamping, then blurring actions before passing the results to this emboss action. Object attributes: action, lineIn, lineOut, opacity, strength, angle, tolerance, keepOnlyChangedAreas, postProcessResults; pseudo-arguments for the convenience method include useNaturalGrayscale, clamp, smoothing.
flood - Set all pixels to the channel values supplied in the “red”, “green”, “blue” and “alpha” arguments. Object attributes: action, lineIn, lineOut, opacity, red, green, blue, alpha; pseudo-arguments for the convenience method include reference - any valid CSS color string from which the channel values will be calculated.
gaussianblur - a fast linear gaussian blur algorithm taken from this GitHub repository: https://github.com/nodeca/glur/blob/master/index.js (code accessed 1 June 2021). Object attributes: action, lineIn, lineOut, opacity, radius.
glitch - CRT television/monitor glitching effect - shifts rows horizontally by a random amount (mediated by limits). Object attributes: action, lineIn, lineOut, opacity, useMixedChannel, seed, step, offsetMin, offsetMax, offsetRedMin, offsetRedMax, offsetGreenMin, offsetGreenMax, offsetBlueMin, offsetBlueMax, offsetAlphaMin, offsetAlphaMax, transparentEdges, level.
grayscale - For each pixel, averages the weighted color channels and applies the result across all the color channels. This gives a more realistic monochrome effect. Object attributes: action, lineIn, lineOut, opacity.
invert-channels - For each pixel, subtracts its current channel values - when included - from 255. Object attributes: action, lineIn, lineOut, opacity, includeRed, includeGreen, includeBlue, includeAlpha.
lock-channels-to-levels - Produces a posterize effect. Takes in four arguments - “red”, “green”, “blue” and “alpha” - each of which is an Array of zero or more integer Numbers (between 0 and 255). The filter works by looking at each pixel’s channel value and determines which of the corresponding Array’s Number values it is closest to; it then sets the channel value to that Number value. Object attributes: action, lineIn, lineOut, opacity, red, green, blue, alpha.
map-to-gradient - maps the colors in the supplied (complex) gradient to a grayscaled input. Object attributes: action, lineIn, lineOut, opacity, useNaturalGrayscale, gradient.
matrix - Performs a matrix operation on each pixel’s channels, calculating the new value using neighbouring pixel weighted values. Also known as a convolution matrix, kernel or mask operation. Note that this filter is expensive, thus much slower to complete compared to other filter effects. The matrix dimensions can be set using the “width” and “height” arguments, while setting the home pixel’s position within the matrix can be set using the “offsetX” and “offsetY” arguments. The weights to be applied need to be supplied in the “weights” argument - an Array listing the weights row-by-row starting from the top-left corner of the matrix. By default all color channels are included in the calculations while the alpha channel is excluded. The ‘edgeDetect’, ‘emboss’ and ‘sharpen’ convenience filter methods all use the matrix action, pre-setting the required weights. Object attributes: action, lineIn, lineOut, opacity, includeRed, includeGreen, includeBlue, includeAlpha, width, height, offsetX, offsetY, weights.
modulate-channels - Multiplies each channel’s value by the supplied argument value. A channel-argument’s value of ‘0’ will set that channel’s value to zero; a value of ‘1’ will leave the channel value unchanged. If the “saturation” flag is set to ‘true’ the calculation changes to start at the color range mid point. The ‘brightness’ and ‘saturation’ filters are special forms of the ‘channels’ filter which use a single “levels” argument to set all three color channel arguments to the same value. Object attributes: action, lineIn, lineOut, opacity, red, green, blue, alpha, saturation; pseudo-argument: level
offset - Offset the input image in the output image. Object attributes: action, lineIn, lineOut, opacity, offsetRedX, offsetRedY, offsetGreenX, offsetGreenY, offsetBlueX, offsetBlueY, offsetAlphaX, offsetAlphaY; pseudo-argument: offsetX, offsetY.
pixelate - Pixelizes the input image by creating a grid of tiles across it and then averaging the color values of each pixel in a tile and setting its value to the average. Tile width and height, and their offset from the top left corner of the image, are set via the “tileWidth”, “tileHeight”, “offsetX” and “offsetY” arguments. Object attributes: action, lineIn, lineOut, opacity, tileWidth, tileHeight, offsetX, offsetY, includeRed, includeGreen, includeBlue, includeAlpha.
process-image - Add an asset image to the filter process chain. The asset - the String name of the asset object - must be pre-loaded before it can be included in the filter. The “width” and “height” arguments are measured in integer Number pixels; the “copy” arguments can be either percentage Strings (relative to the asset’s natural dimensions) or absolute Number values (in pixels). The “lineOut” argument is required - be aware that the filter action does not check for any pre-existing assets cached under this name and, if they exist, will overwrite them with this asset’s data. Object attributes: action, lineOut, asset, width, height, copyWidth, copyHeight, copyX, copyY.
reduce-palette - Reduce the number of colors in an image palette. The palette attribute can be: a Number (for the commonest colors); an Array of CSS color Strings to use as the palette; or the String name of a pre-defined palette - default: ‘black-white’. All internal color comparisons to match pixels to the closest palette color happen in the LAB color space. Dithering is applied to select the closest, or second closest, color when setting each pixel’s final output color; dithering can be random (default), or blue-noise. When calculating commonest colors, a minimum color distance can be set to get a better representative spread for images which have a predominant color (eg: images containing sky, clouds, vegetation or a plain background); calculating the commonest colors can take place in either the RGB space, or the LAB space. The Object attributes: action, lineIn, lineOut, lineMix, opacity, palette, useBluenoise, minimumColorDistance, useLabForPaletteDistance.
set-channel-to-level - Sets the value of each pixel’s included channel to the value supplied in the “level” argument. Object attributes: action, lineIn, lineOut, opacity, includeRed, includeGreen, includeBlue, includeAlpha, level.
step-channels - Takes three divisor values - “red”, “green”, “blue”. For each pixel, its color channel values are divided by the corresponding color divisor, rounded down or up to the integer value and then multiplied by the divisor. For example a divisor value of ‘50’ applied to a channel value of ‘120’ will give a result of ‘100’ (if clamp is set to “down” or “round”) or ‘150’ (clamp set to “up”). The output is a form of posterization. Object attributes: action, lineIn, lineOut, opacity, red, green, blue, clamp.
swirl - For each pixel, move the pixel radially according to its distance from a given coordinate and associated angle for that coordinate. Object attributes: action, lineIn, lineOut, opacity, swirls (array of arrays); pseudo-arguments (for one swirl): startX, startY, innerRadius, outerRadius, angle, easing, staticSwirls`. Note that the start paramenters can be absolute (Number) or relative (String) values, with values relative to the host Cell’s dimensions; inner and outer radius values can also be Strings relative to the host Cell’s width. Supported easing values are included in demo Filters-026.
threshold - Grayscales the input then, for each pixel, checks the color channel values against a “level” argument: pixels with channel values above the level value are assigned to the ‘high’ color; otherwise they are updated to the ‘low’ color. The “high” and “low” arguments are [red, green, blue] integer Number Arrays. The convenience function will accept the pseudo-attributes “highRed”, “lowRed” etc in place of the “high” and “low” Arrays. Object attributes: action, lineIn, lineOut, opacity, low, high; pseudo-arguments: lowRed, lowGreen, lowBlue, highRed, highGreen, highBlue; this filter also accepts lowColor and highColor pseudo-attributes - CSS color Strings in place of the lowRed, lowGreen, lowBlue, highRed, highGreen, highBlue values.
tint-channels - Has similarities to the SVG action, lineIn, lineOut, opacity, redInRed, redInGreen, redInBlue, greenInRed, greenInGreen, greenInBlue, blueInRed, blueInGreen, blueInBlue; pseudo-arguments for the convenience method include reference - any valid CSS color string from which the channel values will be calculated; pseudo-arguments for the convenience method include redColor, greenColor, blueColor - any valid CSS color string from which the rgbIn values will be calculated.
user-defined-legacy - Previous to Scrawl-canvas version 8.4.0, filters could be defined with an argument which passed a function string to a filter web worker, which the worker would then run against the source input image as-and-when required. This functionality has been removed from the new filter system. All such filters will now return the input image unchanged. Object attributes: action, lineIn, lineOut, opacity.
vary-channels-by-weights - curves filter (for image processing tonality). The weights array must by 1024 elements long, with each element defaulting to a value of 1.0. Object attributes: action, lineIn, lineOut, opacity, weights, useMixedChannel.
// Example: the following code creates a filter that applies a thick red border around the entitys
// it is applied to; if used on a group then it will outline the outside of the group's entitys,
// ignoring overlaps between entitys:
scrawl.makeFilter({
name: 'redBorder',
actions: [
{
action: 'blur',
lineIn: 'source-alpha',
lineOut: 'shadow',
radius: 3,
passes: 2,
includeRed: false,
includeGreen: false,
includeBlue: false,
includeAlpha: true,
},
{
action: 'binary',
lineIn: 'shadow',
lineOut: 'shadow',
alpha: 1,
},
{
action: 'flood',
lineIn: 'shadow',
lineOut: 'red-flood',
red: 255,
},
{
action: 'compose',
lineIn: 'shadow',
lineMix: 'red-flood',
lineOut: 'colorized',
compose: 'destination-in',
},
{
action: 'compose',
lineIn: 'source',
lineMix: 'colorized',
}
],
});
import { constructors, cell, group, entity, asset, styles } from '../core/library.js';
import { mergeOver, removeItem, λnull, Ωempty } from '../core/utilities.js';
import { makeGradient } from './gradient.js';
import baseMix from '../mixin/base.js';const Filter = function (items = Ωempty) {
this.makeName(items.name);
this.register();
this.actions = [];
this.set(items);
return this;
};let P = Filter.prototype = Object.create(Object.prototype);
P.type = 'Filter';
P.lib = 'filter';
P.isArtefact = false;
P.isAsset = false;P = baseMix(P);let defaultAttributes = {Filter actions are defined in action objects - which are vanilla Javascript Objects collected together in the actions array. Each action object is processed sequentially by the filter engine to produce the final output for that filter.
actions: null,The method attribute is a String which, in legacy filters, determines the actions which that filter will take on the image. An entity, Group or Cell can include more than one filter object in its filters Array.
method attribute in their argument object do not need to include an actions attribute; the factory will build the action objects for us.method attribute, other attributes can be included alongside it. The filter factory will automatically transpose these attributes to the action object.'alphaToChannels', 'areaAlpha', 'binary', 'blend', 'blue', 'blur', 'brightness', 'channelLevels', 'channels', 'channelstep', 'channelsToAlpha', 'chroma', 'chromakey', 'clampChannels', 'compose', 'corrode', 'curveWeights', 'cyan', 'displace', 'edgeDetect', 'emboss', 'flood', 'gaussianBlur', 'gray', 'grayscale', 'green', 'image', 'invert', 'magenta', 'mapToGradient', 'matrix', 'matrix5', 'notblue', 'notgreen', 'notred', 'offset', 'offsetChannels', 'pixelate', 'randomNoise', 'red', 'reducePalette', 'saturation', 'sepia', 'sharpen', 'swirl', 'threshold', 'tint', 'userDefined', 'yellow'. method: '',The Scrawl-canvas filter engine can use multiple pathways to process a filter’s Array of action objects. In essence, a filter action can store the results of its work in a named cache, which can then be used by other filter actions further down the line.
filters Array looking for any process-image actions; when it finds one it will add a snapshot of the associated asset’s current image state to the filter object (thus Cell and Noise assets are naturally dynamic).isStencil flag has been set to true) then a snapshot of the background behind the entity/Group/Cell is sent instead of the entitys themselves.source cache, and replicates it into the work object.work object.source, which copies the original source image data and delivers it to the action; and source-alpha which copies the original source’s alpha channel data to each of the color channels and delivers it to the action.work objectblend, compose and displace - use two inputs, combining the data referenced by the lineIn and lineMix attribute into lineOut cache or work object. lineIn: '',
lineMix: '',
lineOut: '',Every action includes an opacity attribute which defines how much of the incoming image data (lineIn) and how much of the processed results gets included in the output data (lineOut)
0, the output consists entirely of input data1 (the default), the output consists entirely of processed data0.7 leads to a result consisting of 30% input data and 70% processed data opacity: 1,The attributes below are used by specific filter actions and/or methods, and the values they take may change according to the filter’s requirements. Check out the following demos to see these attributes in action with each filter method:
alpha: 255,
angle: 0,
areaAlphaLevels: null,
asset: '',
blend: 'normal',
blue: 0,
blueInBlue: 0,
blueColor: 'rgba(0 0 0 / 1)',
blueInGreen: 0,
blueInRed: 0,
channelX: 'red',
channelY: 'green',
clamp: 0,
compose: 'source-over',
copyHeight: 1,
copyWidth: 1,
copyX: 0,
copyY: 0,
concurrent: false,
easing: 'linear',
excludeAlpha: true,
excludeBlue: false,
excludeGreen: false,
excludeRed: false,
excludeTransparentPixels: true,
gradient: null,
green: 0,
greenInBlue: 0,
greenColor: 'rgba(0 0 0 / 1)',
greenInGreen: 0,
greenInRed: 0,
gutterHeight: 1,
gutterWidth: 1,
height: 1,
highAlpha: 255,
highBlue: 255,
highColor: 'rgba(255 255 255 / 1)',
highGreen: 255,
highRed: 255,
includeAlpha: false,
includeBlue: true,
includeGreen: true,
includeRed: true,
innerRadius: 0,
keepOnlyChangedAreas: false,
level: 0,
lowAlpha: 0,
lowBlue: 0,
lowColor: 'rgba(0 0 0 / 1)',
lowGreen: 0,
lowRed: 0,
minimumColorDistance: 1000,
noWrap: false,
offsetAlphaX: 0,
offsetAlphaY: 0,
offsetBlueX: 0,
offsetBlueY: 0,
offsetGreenX: 0,
offsetGreenY: 0,
offsetRedX: 0,
offsetRedY: 0,
offsetX: 0,
offsetY: 0,
offsetAlphaMin: 0,
offsetAlphaMax: 0,
offsetBlueMin: 0,
offsetBlueMax: 0,
offsetGreenMin: 0,
offsetGreenMax: 0,
offsetRedMin: 0,
offsetRedMax: 0,
offsetMin: 0,
offsetMax: 0,
opaqueAt: 1,
operation: 'mean',
outerRadius: '30%',
palette: 'black-white',
passes: 1,
points: null,
postProcessResults: true,
processHorizontal: true,
processVertical: true,
radius: 1,
ranges: null,
red: 0,
redInBlue: 0,
redColor: 'rgba(0 0 0 / 1)',
redInGreen: 0,
redInRed: 0,
reference: 'black',
scaleX: 1,
scaleY: 1,
seed: 'some-random-string-or-other',
smoothing: 0,
startX: '50%',
startY: '50%',
step: 1,
strength: 1,
staticSwirls: null,
tileHeight: 1,
tileWidth: 1,
tileRadius: 1,
tolerance: 0,
transparentAt: 0,
transparentEdges: false,
useBluenoise: false,
useLabForPaletteDistance: false,
useMixedChannel: true,
useNaturalGrayscale: false,
weights: null,
width: 1,
};
P.defs = mergeOver(P.defs, defaultAttributes);P.kill = function () {
let myname = this.name;Remove filter from all entity filters attribute
Object.entries(entity).forEach(([name, ent]) => {
let f = ent.filters;
if (f && f.indexOf(myname) >= 0) removeItem(f, myname);
});Remove filter from all group filters attribute
Object.entries(group).forEach(([name, grp]) => {
let f = grp.filters;
if (f && f.indexOf(myname) >= 0) removeItem(f, myname);
});Remove filter from all cell filters attribute
Object.entries(cell).forEach(([name, c]) => {
let f = c.filters;
if (f && f.indexOf(myname) >= 0) removeItem(f, myname);
});Remove filter from the Scrawl-canvas library
this.deregister();
return this;
};let S = P.setters,
D = P.deltaSetters;
P.set = function (items = Ωempty) {
const keys = Object.keys(items),
keysLen = keys.length;
if (keysLen) {
const setters = this.setters,
defs = this.defs;
let predefined, i, key, value;
for (i = 0; i < keysLen; i++) {
key = keys[i];
value = items[key];
if (key && key !== 'name' && value != null) {
predefined = setters[key];
if (predefined) predefined.call(this, value);
else if (typeof defs[key] !== 'undefined') this[key] = value;
}
}
}
if (this.method && setActionsArray[this.method]) setActionsArray[this.method](this);
this.dirtyFilterIdentifier = true;
return this;
};
P.setDelta = function (items = Ωempty) {
const keys = Object.keys(items),
keysLen = keys.length;
if (keysLen) {
const setters = this.deltaSetters,
defs = this.defs;
let predefined, i, iz, key, value;
for (i = 0; i < keysLen; i++) {
key = keys[i];
value = items[key];
if (key && key !== 'name' && value != null) {
predefined = setters[key];
if (predefined) predefined.call(this, value);
else if (typeof defs[key] !== 'undefined') this[key] = addStrings(this[key], value);
}
}
}
if (this.method && setActionsArray[this.method]) setActionsArray[this.method](this);
this.dirtyFilterIdentifier = true;
return this;
};
S.actions = function (item) {
if (item != null) this.actions = item;
};The Scrawl-canvas filters code was rewritten from scratch for version 8.4.0. The new functionality introduced the concept of “line processing” - lineIn, lineMix, lineOut (analagous to SVG in, in2 and result attributes) - alongside the addition of more sophisticated image processing tools such as blend modes, compositing, more adaptable matrices, image loading, displacement mapping, etc.
The legacy system - defining filters using method String attributes - has been adapted to use the new system behind the scenes. As a result all legacy filters will continue to work as expected - with one exception: user-defined filters, which allowed the user to code a function string to pass on to the filter engine, will no longer function in Scrawl-canvas v8.4.0+.
Note that there are no plans to deprecate the legacy method of defining/creating Filters. The following code will continue to work:
// __Brightness__ filter
scrawl.makeFilter({
name: 'my-bright-filter',
method: 'brightness',
level: 0.5,
// __Threshhold__ filter
}).clone({
name: 'my-duotone-filter',
method: 'threshold',
level: 127,
lowRed: 100,
lowGreen: 0,
lowBlue: 0,
highRed: 220,
highGreen: 60,
highBlue: 60,
});
setActionsArray - an object containing a large number of functions which will convert legacy factory function invocations (using method strings) into modern Filter objects (using actions arrays):
const setActionsArray = {alphaToChannels (new in v8.4.0) - copies the alpha channel value over to the selected value or, alternatively, sets that channels value to zero, or leaves the channel’s value unchanged. Setting the appropriate includeChannel flags will copy the alpha channel value to that channel; when that flag is false, setting the appropriate excludeChannel flag will set that channel’s value to zero.
alphaToChannels: function (f) {
f.actions = [{
action: 'alpha-to-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
excludeRed: (f.excludeRed != null) ? f.excludeRed : true,
excludeGreen: (f.excludeGreen != null) ? f.excludeGreen : true,
excludeBlue: (f.excludeBlue != null) ? f.excludeBlue : true,
}];
},areaAlpha (new in v8.4.0) - places a tile schema across the input, quarters each tile and then sets the alpha channels of the pixels in selected quarters of each tile to zero. Can be used to create horizontal or vertical bars, or chequerboard effects.
areaAlpha: function (f) {
f.actions = [{
action: 'area-alpha',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
tileWidth: (f.tileWidth != null) ? f.tileWidth : 1,
tileHeight: (f.tileHeight != null) ? f.tileHeight : 1,
offsetX: (f.offsetX != null) ? f.offsetX : 0,
offsetY: (f.offsetY != null) ? f.offsetY : 0,
gutterWidth: (f.gutterWidth != null) ? f.gutterWidth : 1,
gutterHeight: (f.gutterHeight != null) ? f.gutterHeight : 1,
areaAlphaLevels: (f.areaAlphaLevels != null) ? f.areaAlphaLevels : [255,0,0,0],
}];
},DEPRECATED! binary - use the updated threshold filter instead, as this functionality has been added to it.
binary: function (f) {
let lowRed = (f.lowRed != null) ? f.lowRed : 0,
lowGreen = (f.lowGreen != null) ? f.lowGreen : 0,
lowBlue = (f.lowBlue != null) ? f.lowBlue : 0,
lowAlpha = (f.lowAlpha != null) ? f.lowAlpha : 255,
highRed = (f.highRed != null) ? f.highRed : 255,
highGreen = (f.highGreen != null) ? f.highGreen : 255,
highBlue = (f.highBlue != null) ? f.highBlue : 255,
highAlpha = (f.highAlpha != null) ? f.highAlpha : 255;
let low = (f.low != null) ? f.low : [lowRed, lowGreen, lowBlue, lowAlpha],
high = (f.high != null) ? f.high : [highRed, highGreen, highBlue, highAlpha];
f.actions = [{
action: 'threshold',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
level: (f.level != null) ? f.level : 128,
red: (f.red != null) ? f.red : 128,
green: (f.green != null) ? f.green : 128,
blue: (f.blue != null) ? f.blue : 128,
alpha: (f.alpha != null) ? f.alpha : 128,
low,
high,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : false,
useMixedChannel: (f.useMixedChannel != null) ? f.useMixedChannel : false,
}];
},blend (new in v8.4.0) - perform a blend operation on two images; available blend options include: 'color-burn', 'color-dodge', 'darken', 'difference', 'exclusion', 'hard-light', 'lighten', 'lighter', 'multiply', 'overlay', 'screen', 'soft-light', 'color', 'hue', 'luminosity', and 'saturation' - see W3C Compositing and Blending recommendations
blend: function (f) {
f.actions = [{
action: 'blend',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
lineMix: (f.lineMix != null) ? f.lineMix : '',
blend: (f.blend != null) ? f.blend : 'normal',
offsetX: (f.offsetX != null) ? f.offsetX : 0,
offsetY: (f.offsetY != null) ? f.offsetY : 0,
opacity: (f.opacity != null) ? f.opacity : 1,
}];
},blue - removes red and green channel color from the image
blue: function (f) {
f.actions = [{
action: 'average-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
excludeRed: true,
excludeGreen: true,
}];
},blur - blurs the image A bespoke blur function. Creates visual artefacts with various settings that might be useful. Strongly advise to memoize the results from this filter as it is resource-intensive.
blur: function (f) {
f.actions = [{
action: 'blur',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : false,
excludeTransparentPixels: (f.excludeTransparentPixels != null) ? f.excludeTransparentPixels : false,
processHorizontal: (f.processHorizontal != null) ? f.processHorizontal : true,
processVertical: (f.processVertical != null) ? f.processVertical : true,
radius: (f.radius != null) ? f.radius : 1,
passes: (f.passes != null) ? f.passes : 1,
step: (f.step != null) ? f.step : 1,
}];
},brightness - adjusts the brightness of the image
brightness: function (f) {
let level = (f.level != null) ? f.level : 1;
f.actions = [{
action: 'modulate-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
red: level,
green: level,
blue: level,
}];
},channelLevels (new in v8.4.0) - produces a posterize effect. Takes in four arguments - red, green, blue and alpha - each of which is an Array of zero or more integer Numbers (between 0 and 255). The filter works by looking at each pixel’s channel value and determines which of the corresponding Array’s Number values it is closest to; it then sets the channel value to that Number value
reference attribute, which will be a valid CSS color string. Use these colors to generate the red, green and blue Arrays. channelLevels: function (f) {
f.actions = [{
action: 'lock-channels-to-levels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
red: (f.red != null) ? f.red : [0],
green: (f.green != null) ? f.green : [0],
blue: (f.blue != null) ? f.blue : [0],
alpha: (f.alpha != null) ? f.alpha : [255],
}];
},channels - adjust the value of each channel by a specified multiplier
channels: function (f) {
f.actions = [{
action: 'modulate-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
red: (f.red != null) ? f.red : 1,
green: (f.green != null) ? f.green : 1,
blue: (f.blue != null) ? f.blue : 1,
alpha: (f.alpha != null) ? f.alpha : 1,
}];
},channelstep - restrict the number of color values that each channel can set by imposing regular bands on each channel
channelstep: function (f) {
let clamp = (f.clamp != null) ? f.clamp : 'down'
if (!['down', 'round', 'up'].includes(clamp)) clamp = 'down';
f.actions = [{
action: 'step-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
clamp,
red: (f.red != null) ? f.red : 1,
green: (f.green != null) ? f.green : 1,
blue: (f.blue != null) ? f.blue : 1,
}];
},channelsToAlpha (new in v8.4.0) - calculates an average value from each pixel’s included channels and applies that value to the alpha channel.
channelsToAlpha: function (f) {
f.actions = [{
action: 'channels-to-alpha',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
}];
},chroma - using an array of range arrays, determine whether a pixel’s values lie entirely within a range’s values and, if true, sets that pixel’s alpha channel value to zero. Each range array comprises six Numbers representing [minimum-red, minimum-green, minimum-blue, maximum-red, maximum-green, maximum-blue] values.
[CSS-color-string, CSS-color-string] chroma: function (f) {
const processedRanges = [],
res = [];
if ((f.ranges != null)) {
f.ranges.forEach(range => {
if (range.length === 6) processedRanges.push(range);
else if (range.length === 2) {
if (range[0].substring && range[1].substring) {
res.length = 0;
range.forEach(col => {
let [r, g, b] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(col);
res.push(r, g, b);
});
}
processedRanges.push(res);
}
})
}
f.actions = [{
action: 'chroma',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
ranges: processedRanges,
}];
},chromakey (new in v8.4.0) - determine the alpha channel value for each pixel depending on the closeness to that pixel’s color channel values to a reference color supplied in the red, green and blue arguments. The sensitivity of the effect can be manipulated using the transparentAt and opaqueAt values, both of which lie in the range 0-1.
reference color string in place of the red, green, blue values chromakey: function (f) {
let red = (f.red != null) ? f.red : 0,
green = (f.green != null) ? f.green : 255,
blue = (f.blue != null) ? f.blue : 0;
if (f.reference != null) {
[red, green, blue] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.reference);
f.red = red;
f.green = green;
f.blue = blue;
delete f.reference;
}
f.actions = [{
action: 'colors-to-alpha',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
red,
green,
blue,
transparentAt: (f.transparentAt != null) ? f.transparentAt : 0,
opaqueAt: (f.opaqueAt != null) ? f.opaqueAt : 1,
}];
},clampChannels (new in v8.4.0) - clamp each color channel to a range set by lowColor and highColor values
lowColor and highColor CSS color Strings in place of the lowRed, lowGreen, lowBlue, highRed, highGreen, highBlue values clampChannels: function (f) {
let lowRed = (f.lowRed != null) ? f.lowRed : 0,
lowGreen = (f.lowGreen != null) ? f.lowGreen : 0,
lowBlue = (f.lowBlue != null) ? f.lowBlue : 0,
highRed = (f.highRed != null) ? f.highRed : 255,
highGreen = (f.highGreen != null) ? f.highGreen : 255,
highBlue = (f.highBlue != null) ? f.highBlue : 255;
if (f.lowColor != null) {
[lowRed, lowGreen, lowBlue] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.lowColor);
f.lowRed = lowRed;
f.lowGreen = lowGreen;
f.lowBlue = lowBlue;
delete f.lowColor;
}
if (f.highColor != null) {
[highRed, highGreen, highBlue] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.highColor);
f.highRed = highRed;
f.highGreen = highGreen;
f.highBlue = highBlue;
delete f.highColor;
}
f.actions = [{
action: 'clamp-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
lowRed,
lowGreen,
lowBlue,
highRed,
highGreen,
highBlue,
}];
},compose (new in v8.4.0) - perform a composite operation on two images; available compose options include: 'destination-only', 'destination-over', 'destination-in', 'destination-out', 'destination-atop', 'source-only', 'source-over' (default), 'source-in', 'source-out', 'source-atop', 'clear', and 'xor' - see W3C Compositing and Blending recommendations
compose: function (f) {
f.actions = [{
action: 'compose',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
lineMix: (f.lineMix != null) ? f.lineMix : '',
compose: (f.compose != null) ? f.compose : 'source-over',
offsetX: (f.offsetX != null) ? f.offsetX : 0,
offsetY: (f.offsetY != null) ? f.offsetY : 0,
opacity: (f.opacity != null) ? f.opacity : 1,
}];
},corrode (new in v8.5.2) - performs a special form of matrix operation on each pixel’s color and alpha channels, calculating the new value using neighbouring pixel values.
width and height arguments, while setting the home pixel’s position within the matrix can be set using the offsetX and offsetY arguments. level attribute. includeRed, includeGreen, includeBlue (all false by default) and includeAlpha (default: true) flags. corrode: function (f) {
f.actions = [{
action: 'corrode',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
width: (f.width != null) ? f.width : 3,
height: (f.height != null) ? f.height : 3,
offsetX: (f.offsetX != null) ? f.offsetX : 1,
offsetY: (f.offsetY != null) ? f.offsetY : 1,
includeRed: (f.includeRed != null) ? f.includeRed : false,
includeGreen: (f.includeGreen != null) ? f.includeGreen : false,
includeBlue: (f.includeBlue != null) ? f.includeBlue : false,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : true,
operation: (f.operation != null) ? f.operation : 'mean',
opacity: (f.opacity != null) ? f.opacity : 1,
}];
},curveWeights (new in v8.6.1) - curves filter (for image processing tonality). The weights array must by 1024 elements long, with each element defaulting to a value of 1.0
curveWeights: function (f) {
f.actions = [{
action: 'vary-channels-by-weights',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
weights: (f.weights != null) ? f.weights : false,
useMixedChannel: (f.useMixedChannel != null) ? f.useMixedChannel : true,
}];
},cyan - removes red channel color from the image, and averages the remaining channel colors
cyan: function (f) {
f.actions = [{
action: 'average-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeGreen: true,
includeBlue: true,
excludeRed: true,
}];
},displace (new in v8.4.0) - moves pixels around the image, based on the color channel values supplied by a displacement map image
displace: function (f) {
f.actions = [{
action: 'displace',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
lineMix: (f.lineMix != null) ? f.lineMix : '',
opacity: (f.opacity != null) ? f.opacity : 1,
channelX: (f.channelX != null) ? f.channelX : 'red',
channelY: (f.channelY != null) ? f.channelY : 'green',
offsetX: (f.offsetX != null) ? f.offsetX : 0,
offsetY: (f.offsetY != null) ? f.offsetY : 0,
scaleX: (f.scaleX != null) ? f.scaleX : 1,
scaleY: (f.scaleY != null) ? f.scaleY : 1,
transparentEdges: (f.transparentEdges != null) ? f.transparentEdges : false,
}];
},edgeDetect (new in v8.4.0) - applies a preset 3x3 edge-detect matrix to the image
edgeDetect: function (f) {
f.actions = [{
action: 'matrix',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
width: 3,
height: 3,
offsetX: 1,
offsetY: 1,
includeRed: true,
includeGreen: true,
includeBlue: true,
includeAlpha: false,
weights: [0,1,0,1,-4,1,0,1,0],
}];
},emboss (new in v8.4.0) - outputs a black-gray-red emboss effect
emboss: function (f) {
const actions = [];
if (f.useNaturalGrayscale) {
actions.push({
action: 'grayscale',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: 'emboss-work',
});
}
else {
actions.push({
action: 'average-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: 'emboss-work',
includeRed: true,
includeGreen: true,
includeBlue: true,
});
}
if (f.clamp) {
actions.push({
action: 'clamp-channels',
lineIn: 'emboss-work',
lineOut: 'emboss-work',
lowRed: 0 + f.clamp,
lowGreen: 0 + f.clamp,
lowBlue: 0 + f.clamp,
highRed: 255 - f.clamp,
highGreen: 255 - f.clamp,
highBlue: 255 - f.clamp,
});
}
if (f.smoothing) {
actions.push({
action: 'gaussian-blur',
lineIn: 'emboss-work',
lineOut: 'emboss-work',
radius: f.smoothing,
});
}
actions.push({
action: 'emboss',
lineIn: 'emboss-work',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
angle: (f.angle != null) ? f.angle : 0,
strength: (f.strength != null) ? f.strength : 1,
tolerance: (f.tolerance != null) ? f.tolerance : 0,
keepOnlyChangedAreas: (f.keepOnlyChangedAreas != null) ? f.keepOnlyChangedAreas : false,
postProcessResults: (f.postProcessResults != null) ? f.postProcessResults : true,
});
f.actions = actions;
},flood (new in v8.4.0) - creates a uniform sheet of the required color, which can then be used by other filter actions
alpha value is given in the range 0-255 (like the color channels), not 0-1 or 0%-100% (as is expected in various CSS color String definitions)reference color string in place of the red, green, blue, alpha values flood: function (f) {
let red = (f.red != null) ? f.red : 0,
green = (f.green != null) ? f.green : 0,
blue = (f.blue != null) ? f.blue : 0,
alpha = (f.alpha != null) ? f.alpha : 255,
excludeAlpha = (f.excludeAlpha != null) ? f.excludeAlpha : false;
if (f.reference != null) {
[red, green, blue, alpha] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.reference);
alpha = Math.round(alpha * 255);
f.red = red;
f.green = green;
f.blue = blue;
f.alpha = alpha;
delete f.reference;
}
f.actions = [{
action: 'flood',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
red,
green,
blue,
alpha,
excludeAlpha,
}];
},gaussianBlur - from this GitHub repository: https://github.com/nodeca/glur/blob/master/index.js (code accessed 1 June 2021)
gaussianBlur: function (f) {
f.actions = [{
action: 'gaussian-blur',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
radius: (f.radius != null) ? f.radius : 1,
}];
},glitch - semi-randomly shift rows left/right
glitch: function (f) {
f.actions = [{
action: 'glitch',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
useMixedChannel: (f.useMixedChannel != null) ? f.useMixedChannel : true,
seed: (f.seed != null) ? f.seed : 'some-random-string-or-other',
step: (f.step != null) ? f.step : 1,
offsetMin: (f.offsetMin != null) ? f.offsetMin : 0,
offsetMax: (f.offsetMax != null) ? f.offsetMax : 0,
offsetRedMin: (f.offsetRedMin != null) ? f.offsetRedMin : 0,
offsetRedMax: (f.offsetRedMax != null) ? f.offsetRedMax : 0,
offsetGreenMin: (f.offsetGreenMin != null) ? f.offsetGreenMin : 0,
offsetGreenMax: (f.offsetGreenMax != null) ? f.offsetGreenMax : 0,
offsetBlueMin: (f.offsetBlueMin != null) ? f.offsetBlueMin : 0,
offsetBlueMax: (f.offsetBlueMax != null) ? f.offsetBlueMax : 0,
offsetAlphaMin: (f.offsetAlphaMin != null) ? f.offsetAlphaMin : 0,
offsetAlphaMax: (f.offsetAlphaMax != null) ? f.offsetAlphaMax : 0,
transparentEdges: (f.transparentEdges != null) ? f.transparentEdges : false,
level: (f.level != null) ? f.level : 0,
}];
},gray (new in v8.4.0) - averages the three color channel colors
gray: function (f) {
f.actions = [{
action: 'average-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeRed: true,
includeGreen: true,
includeBlue: true,
}];
},grayscale - produces a more realistic black-and-white photograph effect
grayscale: function (f) {
f.actions = [{
action: 'grayscale',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
}];
},green - removes red and blue channel color from the image
green: function (f) {
f.actions = [{
action: 'average-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
excludeRed: true,
excludeBlue: true,
}];
},image (new in v8.4.0) - load an image into the filter engine, where it can then be used by other filter actions - useful for effects such as watermarking an image
image: function (f) {
f.actions = [{
action: 'process-image',
lineOut: (f.lineOut != null) ? f.lineOut : '',
asset: (f.asset != null) ? f.asset : '',
width: (f.width != null) ? f.width : 1,
height: (f.height != null) ? f.height : 1,
copyWidth: (f.copyWidth != null) ? f.copyWidth : 1,
copyHeight: (f.copyHeight != null) ? f.copyHeight : 1,
copyX: (f.copyX != null) ? f.copyX : 0,
copyY: (f.copyY != null) ? f.copyY : 0,
}];
},invert - inverts the colors in the image, producing an effect similar to a photograph negative
invert: function (f) {
f.actions = [{
action: 'invert-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeRed: true,
includeGreen: true,
includeBlue: true,
}];
},magenta - removes green channel color from the image, and averages the remaining channel colors
magenta: function (f) {
f.actions = [{
action: 'average-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeRed: true,
includeBlue: true,
excludeGreen: true,
}];
},mapToGradient - produces a more realistic black-and-white photograph effect
mapToGradient: function (f) {
if (f.gradient && f.gradient.substring) f.gradient = styles[f.gradient];
f.actions = [{
action: 'map-to-gradient',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
useNaturalGrayscale: (f.useNaturalGrayscale != null) ? f.useNaturalGrayscale : false,
gradient: f.gradient || makeGradient(),
}];
},matrix - applies a 3x3 convolution matrix, kernel or mask operation to the image
matrix: function (f) {
f.actions = [{
action: 'matrix',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
width: 3,
height: 3,
offsetX: 1,
offsetY: 1,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : false,
weights: (f.weights != null) ? f.weights : [0,0,0,0,1,0,0,0,0],
}];
},matrix5 - applies a 5x5 convolution matrix, kernel or mask operation to the image
matrix5: function (f) {
f.actions = [{
action: 'matrix',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
width: 5,
height: 5,
offsetX: 2,
offsetY: 2,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : false,
weights: (f.weights != null) ? f.weights : [0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0],
}];
},newsprint - removes red and green channel color from the image
newsprint: function (f) {
f.actions = [{
action: 'newsprint',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
width: (f.width != null) ? f.width : 1,
}];
},notblue - zeroes the blue channel values (not the same effect as the yellow filter)
notblue: function (f) {
f.actions = [{
action: 'set-channel-to-level',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeBlue: true,
level: 0,
}];
},notgreen - zeroes the green channel values (not the same effect as the magenta filter)
notgreen: function (f) {
f.actions = [{
action: 'set-channel-to-level',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeGreen: true,
level: 0,
}];
},notred - zeroes the red channel values (not the same effect as the cyan filter)
notred: function (f) {
f.actions = [{
action: 'set-channel-to-level',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeRed: true,
level: 0,
}];
},offset (new in v8.4.0) - moves the image in its entirety by the given offset
offset: function (f) {
f.actions = [{
action: 'offset',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
offsetRedX: (f.offsetX != null) ? f.offsetX : 0,
offsetRedY: (f.offsetY != null) ? f.offsetY : 0,
offsetGreenX: (f.offsetX != null) ? f.offsetX : 0,
offsetGreenY: (f.offsetY != null) ? f.offsetY : 0,
offsetBlueX: (f.offsetX != null) ? f.offsetX : 0,
offsetBlueY: (f.offsetY != null) ? f.offsetY : 0,
offsetAlphaX: (f.offsetX != null) ? f.offsetX : 0,
offsetAlphaY: (f.offsetY != null) ? f.offsetY : 0,
}];
},offsetChannels (new in v8.4.0) - moves each channel by an offset set for that channel. Can create a crude stereoscopic output
offsetChannels: function (f) {
f.actions = [{
action: 'offset',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
offsetRedX: (f.offsetRedX != null) ? f.offsetRedX : 0,
offsetRedY: (f.offsetRedY != null) ? f.offsetRedY : 0,
offsetGreenX: (f.offsetGreenX != null) ? f.offsetGreenX : 0,
offsetGreenY: (f.offsetGreenY != null) ? f.offsetGreenY : 0,
offsetBlueX: (f.offsetBlueX != null) ? f.offsetBlueX : 0,
offsetBlueY: (f.offsetBlueY != null) ? f.offsetBlueY : 0,
offsetAlphaX: (f.offsetAlphaX != null) ? f.offsetAlphaX : 0,
offsetAlphaY: (f.offsetAlphaY != null) ? f.offsetAlphaY : 0,
}];
},pixelate - averages the colors in a block to produce a series of obscuring tiles. This is a simplified version of the tiles filter
pixelate: function (f) {
f.actions = [{
action: 'pixelate',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
tileWidth: (f.tileWidth != null) ? f.tileWidth : 1,
tileHeight: (f.tileHeight != null) ? f.tileHeight : 1,
offsetX: (f.offsetX != null) ? f.offsetX : 0,
offsetY: (f.offsetY != null) ? f.offsetY : 0,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : false,
}];
},randomNoise (new in v8.6.0) - creates a stippling effect across the image
randomNoise: function (f) {
f.actions = [{
action: 'random-noise',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
width: (f.width != null) ? f.width : 1,
height: (f.height != null) ? f.height : 1,
seed: (f.seed != null) ? f.seed : 'some-random-string-or-other',
level: (f.level != null) ? f.level : 0,
noWrap: (f.noWrap != null) ? f.noWrap : false,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : true,
excludeTransparentPixels: (f.excludeTransparentPixels != null) ? f.excludeTransparentPixels : true,
}];
},red - removes blue and green channel color from the image
red: function (f) {
f.actions = [{
action: 'average-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
excludeGreen: true,
excludeBlue: true,
}];
},reducePalette - reduce the number of colors in its palette
reducePalette: function (f) {
let palette = (f.palette != null) ? f.palette : 'black-white';
f.actions = [];
if (palette.substring) {
if (palette.includes(',')) {
palette = palette.split(',');
palette.forEach(p => p.trim());
}
}
f.actions.push({
action: 'reduce-palette',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
seed: (f.seed != null) ? f.seed : 'some-random-string-or-other',
minimumColorDistance: (f.minimumColorDistance != null) ? f.minimumColorDistance : 1000,
useLabForPaletteDistance: (f.useLabForPaletteDistance != null) ? f.useLabForPaletteDistance : false,
palette,
useBluenoise: (f.useBluenoise != null) ? f.useBluenoise : false,
opacity: (f.opacity != null) ? f.opacity : 1,
});
},saturation - alters the saturation level of the image
saturation: function (f) {
let level = (f.level != null) ? f.level : 1;
f.actions = [{
action: 'modulate-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
red: level,
green: level,
blue: level,
saturation: true,
}];
},sepia - recalculates the values of each color channel (a tint action) to create a more ‘antique’ version of the image
sepia: function (f) {
f.actions = [{
action: 'tint-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
redInRed: 0.393,
redInGreen: 0.349,
redInBlue: 0.272,
greenInRed: 0.769,
greenInGreen: 0.686,
greenInBlue: 0.534,
blueInRed: 0.189,
blueInGreen: 0.168,
blueInBlue: 0.131,
}];
},sharpen (new in v8.4.0) - applies a preset 3x3 sharpen matrix to the image
sharpen: function (f) {
f.actions = [{
action: 'matrix',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
width: 3,
height: 3,
offsetX: 1,
offsetY: 1,
includeRed: true,
includeGreen: true,
includeBlue: true,
includeAlpha: false,
weights: [0,-1,0,-1,5,-1,0,-1,0],
}];
},swirl - for each pixel, move the pixel radially according to its distance from a given coordinate and associated angle for that coordinate.
swirl: function (f) {
let startX = (f.startX != null) ? f.startX : '50%',
startY = (f.startY != null) ? f.startY : '50%',
innerRadius = (f.innerRadius != null) ? f.innerRadius : 0,
outerRadius = (f.outerRadius != null) ? f.outerRadius : '30%',
angle = (f.angle != null) ? f.angle : 0,
easing = (f.easing != null) ? f.easing : 'linear',
staticSwirls = (f.staticSwirls != null) ? f.staticSwirls : [];
const swirls = [...staticSwirls];
swirls.push([startX, startY, innerRadius, outerRadius, angle, easing]);
f.actions = [{
action: 'swirl',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
swirls,
}];
},threshold - creates a duotone effect - grayscales the input then, for each pixel, checks the color channel values against a “level” argument: pixels with channel values above the level value are assigned to the ‘high’ color; otherwise they are updated to the ‘low’ color.
lowColor and highColor CSS color Strings in place of the lowRed, lowGreen, lowBlue, highRed, highGreen, highBlue values threshold: function (f) {
let lowRed = (f.lowRed != null) ? f.lowRed : 0,
lowGreen = (f.lowGreen != null) ? f.lowGreen : 0,
lowBlue = (f.lowBlue != null) ? f.lowBlue : 0,
lowAlpha = (f.lowAlpha != null) ? f.lowAlpha : 255,
highRed = (f.highRed != null) ? f.highRed : 255,
highGreen = (f.highGreen != null) ? f.highGreen : 255,
highBlue = (f.highBlue != null) ? f.highBlue : 255,
highAlpha = (f.highAlpha != null) ? f.highAlpha : 255;
if (f.lowColor != null) {
[lowRed, lowGreen, lowBlue, lowAlpha] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.lowColor);
lowAlpha = Math.round(lowAlpha * 255);
f.lowRed = lowRed;
f.lowGreen = lowGreen;
f.lowBlue = lowBlue;
f.lowAlpha = lowAlpha;
f.low = [lowRed, lowGreen, lowBlue, lowAlpha];
delete f.lowColor;
}
if (f.highColor != null) {
[highRed, highGreen, highBlue, highAlpha] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.highColor);
highAlpha = Math.round(highAlpha * 255);
f.highRed = highRed;
f.highGreen = highGreen;
f.highBlue = highBlue;
f.highAlpha = highAlpha;
f.high = [highRed, highGreen, highBlue, highAlpha];
delete f.highColor;
}
let low = (f.low != null) ? f.low : [lowRed, lowGreen, lowBlue, lowAlpha],
high = (f.high != null) ? f.high : [highRed, highGreen, highBlue, highAlpha];
f.actions = [{
action: 'threshold',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
level: (f.level != null) ? f.level : 128,
red: (f.red != null) ? f.red : 128,
green: (f.green != null) ? f.green : 128,
blue: (f.blue != null) ? f.blue : 128,
alpha: (f.alpha != null) ? f.alpha : 128,
low,
high,
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : false,
useMixedChannel: (f.useMixedChannel != null) ? f.useMixedChannel : true,
}];
},tiles - averages the colors in a group of pixels to produce a series of obscuring tiles. This is a more complex version of the pixelate filter
tiles: function (f) {
f.actions = [{
action: 'tiles',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
tileWidth: (f.tileWidth != null) ? f.tileWidth : 1,
tileHeight: (f.tileHeight != null) ? f.tileHeight : 1,
tileRadius: (f.tileRadius != null) ? f.tileRadius : 1,
offsetX: (f.offsetX != null) ? f.offsetX : 0,
offsetY: (f.offsetY != null) ? f.offsetY : 0,
angle: (f.angle != null) ? f.angle : 0,
points: (f.points != null) ? f.points : 'rect-grid',
seed: (f.seed != null) ? f.seed : 'some-random-string-or-other',
includeRed: (f.includeRed != null) ? f.includeRed : true,
includeGreen: (f.includeGreen != null) ? f.includeGreen : true,
includeBlue: (f.includeBlue != null) ? f.includeBlue : true,
includeAlpha: (f.includeAlpha != null) ? f.includeAlpha : false,
}];
},tint - has similarities to the SVG <feColorMatrix> filter element, but excludes the alpha channel from calculations. Rather than set a matrix, we set nine arguments to determine how the value of each color channel in a pixel will affect both itself and its fellow color channels.
tint: function (f) {
let redInRed = (f.redInRed != null) ? f.redInRed : 1,
redInGreen = (f.redInGreen != null) ? f.redInGreen : 0,
redInBlue = (f.redInBlue != null) ? f.redInBlue : 0,
greenInRed = (f.greenInRed != null) ? f.greenInRed : 0,
greenInGreen = (f.greenInGreen != null) ? f.greenInGreen : 1,
greenInBlue = (f.greenInBlue != null) ? f.greenInBlue : 0,
blueInRed = (f.blueInRed != null) ? f.blueInRed : 0,
blueInGreen = (f.blueInGreen != null) ? f.blueInGreen : 0,
blueInBlue = (f.blueInBlue != null) ? f.blueInBlue : 1;
if (f.redColor != null) {
[redInRed, greenInRed, blueInRed] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.redColor);
redInRed /= 255;
greenInRed /= 255;
blueInRed /= 255;
f.redInRed = redInRed;
f.greenInRed = greenInRed;
f.blueInRed = blueInRed;
delete f.redColor;
}
if (f.greenColor != null) {
[redInGreen, greenInGreen, blueInGreen] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.greenColor);
redInGreen /= 255;
greenInGreen /= 255;
blueInGreen /= 255;
f.redInGreen = redInGreen;
f.greenInGreen = greenInGreen;
f.blueInGreen = blueInGreen;
delete f.greenColor;
}
if (f.blueColor != null) {
[redInBlue, greenInBlue, blueInBlue] = window.scrawlEnvironmentColorChecker.extractRGBfromColor(f.blueColor);
redInBlue /= 255;
greenInBlue /= 255;
blueInBlue /= 255;
f.redInBlue = redInBlue;
f.greenInBlue = greenInBlue;
f.blueInBlue = blueInBlue;
delete f.blueColor;
}
f.actions = [{
action: 'tint-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
redInRed,
redInGreen,
redInBlue,
greenInRed,
greenInGreen,
greenInBlue,
blueInRed,
blueInGreen,
blueInBlue,
}];
},userDefined - DEPRECATED - this filter method no longer has any effect, returning an unchanged image
userDefined: function (f) {
f.actions = [{
action: 'user-defined-legacy',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
}];
},yellow - removes blue channel color from the image, and averages the remaining channel colors
yellow: function (f) {
f.actions = [{
action: 'average-channels',
lineIn: (f.lineIn != null) ? f.lineIn : '',
lineOut: (f.lineOut != null) ? f.lineOut : '',
opacity: (f.opacity != null) ? f.opacity : 1,
includeRed: true,
includeGreen: true,
excludeBlue: true,
}];
},
};const makeFilter = function (items) {
if (!items) return false;
return new Filter(items);
};
constructors.Filter = Filter;export {
makeFilter,
};