ImageIO not able to write a JPEG file

Question

I have a BufferedImage I\'m trying to write to a jpeg file, but my Java program throws an exception. I\'m able to successfully save the same buffer to a gif and png. I\'ve t

Answer 1

2019 answer: Make sure your BufferedImage does not have alpha transparency. JPEG does not support alpha, so if your image has alpha then ImageIO cannot write it to JPEG.

Use the following code to ensure your image does not have alpha transparancy:

static BufferedImage ensureOpaque(BufferedImage bi) {
    if (bi.getTransparency() == BufferedImage.OPAQUE)
        return bi;
    int w = bi.getWidth();
    int h = bi.getHeight();
    int[] pixels = new int[w * h];
    bi.getRGB(0, 0, w, h, pixels, 0, w);
    BufferedImage bi2 = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
    bi2.setRGB(0, 0, w, h, pixels, 0, w);
    return bi2;
}