Converting PNG into JPEG

user_260945 0
Viewed 25729

I'm having problems converting a simple PNG into a JPEG format. I'm using the following code:

...

    File png = new File(filePath);
    try {
        SeekableStream s = new FileSeekableStream(png);
        PNGDecodeParam pngParams = new PNGDecodeParam();
        ImageDecoder dec = ImageCodec.createImageDecoder("png", s, pngParams);
        RenderedImage pngImage = dec.decodeAsRenderedImage();
        JPEGEncodeParam jparam = new JPEGEncodeParam();
        jparam.setQuality(0.50f); // e.g. 0.25f
        File jpeg = new File("jpeg.jpeg");
        FileOutputStream out = new FileOutputStream(jpeg);

        ImageEncoder encoder = ImageCodec.createImageEncoder("JPEG", out, jparam); 

        encoder.encode(pngImage);

        s.close();

    } catch (IOException e) {
        ok = false;
        e.printStackTrace();
    }

    return ok;
}

...

I end up with an JAI exception -> java.lang.RuntimeException: Only 1, or 3-band byte data may be written. at com.sun.media.jai.codecimpl.JPEGImageEncoder.encode(JPEGImageEncoder.java:148) ...

Ran out of options. Any suggestion?

jai png jpeg image java
7 Answers

It might be easier to use ImageIO to read the PNG into a BufferedImage and write the image out in JPEG format.

Addendum: In this approach, the conversion is handled transparently by the writer's ImageTranscoder.

BufferedImage img = ImageIO.read(new File("image.png"));
ImageIO.write(img, "jpg", new File("image.jpg"));
user_2305130

you probably have alpha channel in the png that you need to get rid of before trying to write the jpg.

Create a new BufferedImage with type TYPE_INT_RGB (not TYPE_INT_ARGB), and then write your source image (pngImage) onto the new blank image.

Something like this (warning, not tested code):

BufferedImage newImage = new BufferedImage( pngImage.getWidth(), pngImage.getHeight(), BufferedImage.TYPE_INT_RGB);
newImage.createGraphics().drawImage( pngImage, 0, 0, Color.BLACK, null);
user_1317950

I suppse that JAI reads the PNG image with an indexed colour model and is only able to write 8-bit grayscale or 24-bit colour images as JPEG files.

If you are not required to use JAI for this task, you should be able to use ImageIO instead:

ImageIO.write(ImageIO.read(new File("in.png")), "JPEG", new File("out.jpg"));
user_1806590

I had corrupted file after conversion with other solutions but this method worked for me:

    public static void formatConverter(String pngFile, String jpgFile) {
        try {

            File input = new File(pngFile);
            File output = new File(jpgFile);

            BufferedImage image = ImageIO.read(input);
            BufferedImage result = new BufferedImage(
                    image.getWidth(),
                    image.getHeight(),
                    BufferedImage.TYPE_INT_RGB);
            result.createGraphics().drawImage(image, 0, 0, Color.WHITE, null);
            ImageIO.write(result, "jpg", output);

        }  catch (IOException e) {
            e.printStackTrace();
        }

    }
user_102711410

see Converting transparent gif / png to jpeg using java

Have a look at the solution that redraws with the graphics environment posted by harmanjd. The solution with the DirectColorModel doesn't compile and should be wiped away. I don't have enough rep points to comment directly there.

user_61956960
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