Image color loss during conversion

[aleksanderFox]

Expected behavior

Please describe what you are expecting the library to perform.
The image does not lose color during conversion.

Actual behavior

Hello!
I'm using the thumbnailator library to compress and convert customers images to png (to default size 200x200).
One user came in with an image that was losing color (black gets lighter).
Perhaps the error is due to the fact that the original image was 16 BitsPerPixel - the result is 32 BitsPerPixel.
Perhaps I'm not using the library correctly.
Help me to understand.

Steps to reproduce the behavior

My code:

    public static final Blob convertResizeImage(BufferedImage image, String formatName/*PNG*/, int targetWidth/*200*/, int targetHeight/*200*/) throws SQLException, IOException, InstantiationException, IllegalAccessException {
        int imgType = image.getType();
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        Thumbnails.of(image)
                .size(targetWidth, targetHeight)
                .outputFormat(formatName)
                .imageType(imgType)
                .outputQuality(1)
                .toOutputStream(outputStream);
        byte[] data = outputStream.toByteArray();
        return bytes2Blob(data);
    }

Source image:

Converted image:

Environment

• OS vendor and version: Windows 10
• JDK vendor and version: Corretto 1.8
• Thumbnailator version: 0.4.18

[coobird]

There have been similar issues reported in the past, and usually it can be solved by forcing the image type to be BufferedImage.TYPE_INT_ARGB by .outputFormat(BufferedImage.TYPE_INT_ARGB) -- not setting this will make Thumbnailator perform image processing on the original image type which could introduce these types of issues.

[aleksanderFox]

Perhaps .outputFormat(BufferedImage.TYPE_INT_ARGB) is a typo?
It was meant .imageType(BufferedImage.TYPE_INT_ARGB)?

        int imgType = originalImage.getType();
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        Thumbnails.of(originalImage)
                .size(targetWidth, targetHeight)
                .outputFormat(formatName)
                //.imageType(imgType)
                .imageType(BufferedImage.TYPE_INT_ARGB)
                .outputQuality(1)
                .toOutputStream(outputStream);

Unfortunately, the above code did not help to fix the error.

[LouisWayne]

I had a similar issue (converting from PNG to JPG) but fixed it by using BufferedImage.TYPE_INT_RGB

BufferedImage thumbnailImg = Thumbnails.of(pngImage)
    .size(width, height)
    .outputFormat("jpg")
    .imageType(BufferedImage.TYPE_INT_RGB) // PNG -> JPG
    .asBufferedImage();

It's a bit cumbersome since we need to set imageType(...) manually