在 BufferedImage 中设置单个像素颜色

BufferedImage image = new BufferedImage(256, 256, BufferedImage.TYPE_INT_ARGB);

//you don't have to use the Graphics object, you can read and set pixel color individually
for (int i = 0; i < 256; i++) {
    for (int j = 0; j < 256; j++) {
        int alpha = 255; //don't forget this, or use BufferedImage.TYPE_INT_RGB instead
        int red = i; //or any formula you like
        int green = j; //or any formula you like
        int blue = 50; //or any formula you like
        int color = (alpha << 24) | (red << 16) | (green << 8) | blue;
        image.setRGB(i, j, color);
    }
}

ImageIO.write(image, "png", new File("computed.png"));

输出：