Function extractBlockGridAverage

web/js/algorithms.js:182–205

(imageData, blockSize)

// ============================================================

function extractBlockGridAverage(imageData, blockSize) {
    const { width, height } = imageData;
    const d = imageData.data;
    const cols = Math.ceil(width / blockSize);
    const rows = Math.ceil(height / blockSize);
    const grid = [];

    for (let row = 0; row < rows; row++) {
        grid[row] = [];
        for (let col = 0; col < cols; col++) {
            const x0 = col * blockSize, y0 = row * blockSize;
            let r = 0, g = 0, b = 0, count = 0;
            for (let dy = 0; dy < blockSize && y0 + dy < height; dy++) {
                for (let dx = 0; dx < blockSize && x0 + dx < width; dx++) {
                    const idx = ((y0 + dy) * width + (x0 + dx)) * 4;
                    r += d[idx]; g += d[idx + 1]; b += d[idx + 2];
                    count++;
                }
            }
            grid[row][col] = [Math.round(r / count), Math.round(g / count), Math.round(b / count)];
        }
    }
    return { grid, cols, rows };
}

function extractBlockGridNearest(imageData, blockSize) {
    const { width, height } = imageData;