image-js/lib/compare/subtract.js

Image processing and manipulation in JavaScript

import { Image } from '../Image.js';
import { Mask } from '../Mask.js';
import checkProcessable from '../utils/validators/checkProcessable.js';
import { validateForComparison } from '../utils/validators/validators.js';
/**
 * Calculate a new image that is the subtraction between the current image and the otherImage.
 * @param image - Image from which to subtract.
 * @param otherImage - Image to subtract.
 * @param options - Subtract options.
 * @returns The subtracted image.
 */
export function subtract(image, otherImage, options = {}) {
    const { absolute = false } = options;
    if (image instanceof Image) {
        checkProcessable(image, {
            bitDepth: [1, 8, 16],
            components: [1, 3],
            alpha: false,
        });
    }
    validateForComparison(image, otherImage);
    const newImage = image.clone();
    if (newImage instanceof Image) {
        for (let index = 0; index < image.size; index++) {
            for (let channel = 0; channel < image.channels; channel++) {
                const value = image.getValueByIndex(index, channel) -
                    otherImage.getValueByIndex(index, channel);
                if (absolute) {
                    if (value < 0) {
                        newImage.setValueByIndex(index, channel, -value);
                    }
                    else {
                        newImage.setValueByIndex(index, channel, value);
                    }
                }
                else if (value < 0) {
                    newImage.setValueByIndex(index, channel, 0);
                }
                else {
                    newImage.setValueByIndex(index, channel, value);
                }
            }
        }
    }
    else if (image instanceof Mask && otherImage instanceof Mask) {
        for (let index = 0; index < image.size; index++) {
            const value = image.getBitByIndex(index) - otherImage.getBitByIndex(index);
            if (absolute) {
                newImage.setBitByIndex(index, value ? 1 : 0);
            }
            else {
                newImage.setBitByIndex(index, value > 0 ? 1 : 0);
            }
        }
    }
    return newImage;
}
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