image-js/lib/operations/extendBorders.js

Image processing and manipulation in JavaScript

import { Image } from '../Image.js';
import { getDefaultColor } from "../utils/getDefaultColor.js";
import { getBorderInterpolation } from '../utils/interpolateBorder.js';
import { validateColor } from "../utils/validators/validators.js";
/**
 * Extend the borders of an image according to the given border type.
 * @param image - Image to extend.
 * @param options - Options.
 * @returns A copy of the image with extended borders.
 */
export function extendBorders(image, options) {
    const { horizontal, vertical, borderType = 'reflect101', borderValue = getDefaultColor(image), } = options;
    if (Array.isArray(borderValue)) {
        validateColor(borderValue, image);
    }
    const interpolateBorder = getBorderInterpolation(borderType, borderValue);
    const newImage = Image.createFrom(image, {
        width: image.width + 2 * horizontal,
        height: image.height + 2 * vertical,
    });
    image.copyTo(newImage, {
        origin: {
            column: horizontal,
            row: vertical,
        },
        out: newImage,
    });
    // Top strip
    for (let row = 0; row < vertical; row++) {
        for (let col = 0; col < newImage.width; col++) {
            for (let channel = 0; channel < image.channels; channel++) {
                const newValue = interpolateBorder(col - horizontal, row - vertical, channel, image);
                newImage.setValue(col, row, channel, newValue);
            }
        }
    }
    // Bottom strip
    for (let row = newImage.height - vertical; row < newImage.height; row++) {
        for (let col = 0; col < newImage.width; col++) {
            for (let channel = 0; channel < image.channels; channel++) {
                const newValue = interpolateBorder(col - horizontal, row - vertical, channel, image);
                newImage.setValue(col, row, channel, newValue);
            }
        }
    }
    // Left strip
    for (let row = vertical; row < newImage.height - vertical; row++) {
        for (let col = 0; col < horizontal; col++) {
            for (let channel = 0; channel < image.channels; channel++) {
                const newValue = interpolateBorder(col - horizontal, row - vertical, channel, image);
                newImage.setValue(col, row, channel, newValue);
            }
        }
    }
    // Right strip
    for (let row = vertical; row < newImage.height - vertical; row++) {
        for (let col = newImage.width - horizontal; col < newImage.width; col++) {
            for (let channel = 0; channel < image.channels; channel++) {
                const newValue = interpolateBorder(col - horizontal, row - vertical, channel, image);
                newImage.setValue(col, row, channel, newValue);
            }
        }
    }
    return newImage;
}
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