ICC based image conversion using Java

Question

I would like to convert images using ICC profiles and Java. The source image can be RGB or CMYK based, and maybe could have an icc profile embeded. The new images should also be in RGB or CMYK color mode, and has to have a icc profile embeded. All source images will be in JPEG format.

Which (external/internal) Java framework/Library should I use ? What approche is the best to use for RGB > CMYK or RGB > RGB or CMYK > CMYK or CMYK > RGB icc based image conversion ?

Are there memory limitations ? Can it handle larger image files ? And how to handle the difference between sRGB an AdobeRGB ?

Does anyone have experience in handling image conversions using Java ?

Thanx

Answer 1

Warning: The question is vague/very wide, so the answer will have to be as well. But here's an attempt at an answer anyway.

The core Java 2D classes have good support for ICC profiles. See ICC_Profile and ICC_ColorSpace.

You can use ColorConvertOp to convert between color spaces (or color profiles). It supports both BufferedImages and WritableRasters, and is generally fast for ICC conversions (uses native libraries behind the scenes). It will handle all the conversions you mentioned, including sRGB and AdobeRGB differences.

So far, so good.

To read and write JPEG files using ICC profiles, things get a little more complicated. In theory, the standard ImageIO API is all you need. You'll need to obtain both the meta data (IIOMetadata) and the pixels (as either Raster or BufferedImage).

The ICC profile will be part of the meta data. You need to obtain the native JPEG metadata specified here. For RGB JPEGs this is all you need.

Unfortunately, the standard JPEGImageReader that is part of all Oracle or OpenJDK JREs does not support reading CMYK data as a BufferedImage. You will have to read as Raster. The raster will usually contain YCbCr or YCCK data, depending on the color transformation used when writing, so you might have to handle that transformation as well. Alternatively, you can use my JPEG plugin for ImageIO which supports CMYK JPEGs directly.

Writing is pretty much the same. Writing RGB is "straight forward" (although it takes a few lines of code), while writing CMYK is harder. The important thing is to use the meta data obtained from the image you read, then replace the ICC profile with the one you have converted to. And finally write the meta data and the updated image data back. My JPEG plugin can also write CMYK JPEGs.

For everything Java 2D and BufferedImage/Raster-related operations, you are normally limited by the available (heap) memory (as well as the maximum array size in Java, should you have that much RAM). There are some workarounds, feel free to look at my MappedImageFactory and MappedFileBuffer classes here for nio MappedByteBuffer (memory mapped file buffer) backed data buffers for BufferedImages. I'm sure JAI also have some options for this, but I generally don't recommend JAI for new code, as it seems completely left in the dark by Oracle.

Good luck! Prepare to spend some time on this, though. 😀