image-js/lib/filters/derivativeFilter.js

Image processing and manipulation in JavaScript

import { match } from 'ts-pattern';
import { PREWITT_X, PREWITT_Y, SCHARR_X, SCHARR_Y, SOBEL_X, SOBEL_Y, } from '../utils/constants/kernels.js';
export const DerivativeFilter = {
    SOBEL: 'sobel',
    SCHARR: 'scharr',
    PREWITT: 'prewitt',
    // todo: handle even sized kernels to implement Roberts' filter
    // for 2x2 matrices, the current pixel corresponds to the top-left
    //  ROBERTS = 'roberts',
};
/**
 * Apply a derivative filter to an image.
 * @param image - Image to process.
 * @param options - Derivative filter options.
 * @returns The processed image.
 */
export function derivativeFilter(image, options = {}) {
    const { filter = 'sobel' } = options;
    const kernels = match(filter)
        .with('sobel', () => ({ kernelX: SOBEL_X, kernelY: SOBEL_Y }))
        .with('scharr', () => ({ kernelX: SCHARR_X, kernelY: SCHARR_Y }))
        .with('prewitt', () => ({ kernelX: PREWITT_X, kernelY: PREWITT_Y }))
        .exhaustive();
    return image.gradientFilter({ ...kernels, ...options });
}
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