type Key = 'auto' | [r: number, g: number, b: number] | {
    color: [r: number, g: number, b: number] | 'auto';
    /**
     * Color tolerance; float ranged 0-1. Higher values result in a larger range of colors being keyed.
     * @default 0.1
     */
    tolerance?: number;
    /**
     * Edge smoothness; float ranged 0-1. Higher values result in more transparency near the key color.
     * @default 0.1
     */
    smoothness?: number;
    /**
     * Spill suppression; float ranged 0-1. Higher values result in more desaturation near the key color.
     * @default 0.1
     */
    spill?: number;
    /**
     * Enable debug visualization for the auto key color detection
     * @default false
     */
    debug?: boolean;
};
interface RenderOptions {
    /**
     * If true, skips chroma key processing and draws source frame verbatim
     * @default false
     */
    passthrough?: boolean;
}
type MediaElement = HTMLVideoElement | HTMLImageElement | HTMLCanvasElement;
declare class GLChromaKey {
    private _gl;
    private _keys;
    private _media;
    private _data;
    private _initialized;
    private _mediaTexture;
    private _paintShader;
    private _alphaFramebuffer;
    private _downsampleCanvas;
    private _downsampleContext;
    private _vertexPositionBuffer;
    private _vertexIndexBuffer;
    private _texCoordBuffer;
    private _vertexArrayObject;
    private _downsampleWidth;
    private _downsampleHeight;
    private _hasAutoKeys;
    /**
     * Creates a new GLChromaKey instance
     * @param source Source video, image or canvas element to key
     * @param target Target canvas element on which to paint keyed image(s)
     */
    constructor(source: HTMLVideoElement | HTMLImageElement | HTMLCanvasElement, target: HTMLCanvasElement | WebGL2RenderingContext);
    private buildWebGlBuffers;
    private setUpShaders;
    private calculateDownsampleSize;
    private initializeTextures;
    private drawScreen;
    private checkReady;
    /**
     * Returns true if browser supports WebGL 2, else false.
     */
    supportsWebGL2(): boolean;
    /**
     * Sets a new source video, image or canvas element to key.
     */
    source(source: MediaElement): this;
    /**
     * Sets a new target canvas on which to paint keyed image(s). The context webgl2 will be used.
     */
    target(target: HTMLCanvasElement | WebGL2RenderingContext): this;
    /**
     * Returns the coordinates of a bounding box around non-transparent pixels in the form [x1, y1, x2, y2]
     */
    getContentBounds(): [x1: number, y1: number, x2: number, y2: number];
    /**
     * Updates frame from source element and paints to target canvas
     * @param options Render options object
     */
    render(options?: RenderOptions): this;
    /**
     * Sets one or more key colors in RGB, replacing any prior settings. Calling without parameters
     * clears all key colors. The auto key color mode downsamples the source image, grabs each corner
     * pixel, and keys on the two pixels with the most similar color. It works best on videos or images
     * with simplistic backgrounds, and can cause flickering if the algorithm gets it wrong. Use with
     * caution.
     *
     * @param keys - One or more key configurations. Each key can be:
     * - `'auto'` - Automatic color detection
     * - `[r, g, b]` - RGB color array (0-255 range)
     * - Object with properties:
     *   - `color: [r, g, b] | 'auto'` - Color to key
     *   - `tolerance?: number` - Color tolerance (0-1, default: 0.1)
     *   - `smoothness?: number` - Edge smoothness (0-1, default: 0.1)
     *   - `spill?: number` - Spill suppression (0-1, default: 0.1)
     *   - `debug?: boolean` - Enable debug visualization (default: false)
     */
    key(...keys: (Key | Key[])[]): this;
    /**
     * Unload all shader and buffers
     */
    unload(): this;
}
export default GLChromaKey;