Convert Image Files To Line Drawings With OpenCV And Node.js

convert_img_to_line_drawing.js

const path = require('path');
const fs = require('fs');

const cv = require('opencv4nodejs');

function convertImageToLineDrawing(img) {
    const kernel = new cv.Mat([
        [1, 1, 1, 1, 1],
        [1, 1, 1, 1, 1],
        [1, 1, 1, 1, 1],
        [1, 1, 1, 1, 1],
        [1, 1, 1, 1, 1],
    ], cv.CV_8U);

    const imgGray = img.cvtColor(cv.COLOR_RGBA2GRAY);

    const imgDilated = imgGray.dilate(kernel, new cv.Point2(-1, 1), 1);

    const imgDiff = imgDilated.absdiff(imgGray);

    const contour = imgDiff.bitwiseNot();
    return contour;
}

function convertImagesToLineDrawing(srcDirPath, destDirPath) {
    const srcFileList = fs.readdirSync(srcDirPath);
    for (const srcFileName of srcFileList) {
        if (!srcFileName.endsWith('.JPG')) {
            continue;
        }
        console.log('Processing ', srcFileName, '...');
        const imgMat = cv.imread(path.join(srcDirPath, srcFileName));
        const imgMatConverted = convertImageToLineDrawing(imgMat);
        cv.imwrite(path.join(destDirPath, srcFileName), imgMatConverted);
    }
}

function main() {
    const srcDirPath = 'SOURCE_DIRECTORY_PATH';
    const destDirPath = 'DEST_DIRECTORY_PATH';
    convertImagesToLineDrawing(srcDirPath, destDirPath);
}

main();