image-js/lib/utils/interpolateBorder.js

Image processing and manipulation in JavaScript

import { match } from 'ts-pattern';
export const BorderType = {
    CONSTANT: 'constant',
    REPLICATE: 'replicate',
    REFLECT: 'reflect',
    WRAP: 'wrap',
    REFLECT_101: 'reflect101',
};
/**
 * Pick the border interpolation algorithm.
 * The different algorithms are illustrated here:
 * @see {@link https://vovkos.github.io/doxyrest-showcase/opencv/sphinx_rtd_theme/enum_cv_BorderTypes.html}
 * @param type - The border type.
 * @param value - A pixel value if BorderType.CONSTANT is used.
 * @returns The border interpolation function.
 */
export function getBorderInterpolation(type, value) {
    if (typeof value === 'number') {
        value = new Array(4).fill(value);
    }
    return match(type)
        .with('constant', () => getInterpolateConstant(value))
        .with('replicate', () => interpolateReplicate)
        .with('reflect', () => interpolateReflect)
        .with('reflect101', () => interpolateReflect101)
        .with('wrap', () => interpolateWrap)
        .exhaustive();
}
function checkRange(point, length) {
    if (point <= 0 - length || point >= length + length - 1) {
        throw new RangeError('border must be smaller than the original image');
    }
}
function getInterpolateConstant(value) {
    return function interpolateConstant(column, row, channel, image) {
        const newColumn = interpolateConstantPoint(column, image.width);
        const newRow = interpolateConstantPoint(row, image.height);
        if (newColumn === -1 || newRow === -1) {
            return value[channel];
        }
        return image.getValue(newColumn, newRow, channel);
    };
}
/**
 * Interpolate using a constant point.
 * @param point - The point to interpolate.
 * @param length  - The length of the image.
 * @returns The interpolated point.
 */
export function interpolateConstantPoint(point, length) {
    if (point >= 0 && point < length) {
        return point;
    }
    return -1;
}
function interpolateReplicate(column, row, channel, image) {
    return image.getValue(interpolateReplicatePoint(column, image.width), interpolateReplicatePoint(row, image.height), channel);
}
/**
 * Interpolate by replicating the border.
 * @param point - The point to interpolate.
 * @param length - The length of the image.
 * @returns The interpolated point.
 */
export function interpolateReplicatePoint(point, length) {
    if (point >= 0 && point < length) {
        return point;
    }
    checkRange(point, length);
    if (point < 0) {
        return 0;
    }
    else {
        return length - 1;
    }
}
function interpolateReflect(column, row, channel, image) {
    return image.getValue(interpolateReflectPoint(column, image.width), interpolateReflectPoint(row, image.height), channel);
}
/**
 * Interpolate by reflecting the border.
 * @param point - The point to interpolate.
 * @param length - The length of the image.
 * @returns The interpolated point.
 */
export function interpolateReflectPoint(point, length) {
    if (point >= 0 && point < length) {
        return point;
    }
    checkRange(point, length);
    if (point < 0) {
        return -1 - point;
    }
    else {
        return length + length - 1 - point;
    }
}
function interpolateWrap(column, row, channel, image) {
    return image.getValue(interpolateWrapPoint(column, image.width), interpolateWrapPoint(row, image.height), channel);
}
/**
 * Interpolate by wrapping the border.
 * @param point - The point to interpolate.
 * @param length - The length of the image.
 * @returns The interpolated point.
 */
export function interpolateWrapPoint(point, length) {
    if (point >= 0 && point < length) {
        return point;
    }
    checkRange(point, length);
    if (point < 0) {
        return length + point;
    }
    else {
        return point - length;
    }
}
function interpolateReflect101(column, row, channel, image) {
    return image.getValue(interpolateReflect101Point(column, image.width), interpolateReflect101Point(row, image.height), channel);
}
/**
 * Interpolate by reflecting the border.
 * @param point - The point to interpolate.
 * @param length - The length of the image.
 * @returns The interpolated point.
 */
export function interpolateReflect101Point(point, length) {
    if (point >= 0 && point < length) {
        return point;
    }
    checkRange(point, length);
    if (point < 0) {
        return 0 - point;
    }
    else {
        return length + length - 2 - point;
    }
}
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