Question

Working with images in Java for the first time and am getting some bizarro exceptions that aren’t documented very well. Here’s the line of code that is failing:

BufferedImage imgSelected = ImageIO.read(new File("/abs/url/to/file/image.jpg"));

This line is throwing an IIOException with Unsupported image type as the exception message. I have checked and re-checked that it is in fact this line throwing the exception, that the File object is valid, that the URL is valid, and that the image.jpg is in fact a valid JPG that loads perfectly fine in other image viewers.

What could I do to get more information about the nature of this exception? Is this the traditional way for loading images in Java 7, or is this an old/deprecating method? There’s just not a lot of info out there about these “Unsupported image type” exceptions, and surely, ImageIO supported JPGs!

Thanks for any help!

Answer 1

Try to check the encoding of the JPEG. ImageIO can’t read CMYK-encoded jpeg images for example.
AFAIK, ImageIO hasn’t been updated for years, so you’d like to try and use the official alternative/extension: JAI ImageIO.

Unforutnately, JAI ImageIO needs some native libraries installed into the JRE, which might be unwanted.
We do the following:

• use Apache Sanselan to detect, whether it’s a JPEG
• since Sanselan can’t read and write JPEG, use the plain old AWT JPEGCodec: JPEGCodec.createJPEGDecoder(...)
• to convert CMYK to RGB, we then get the raster of the read BufferedImage and manually convert it (you could use ICC profiles, but the manual conversion fits our needs)

Here’s a question of mine that resulted of the fact that ImageIO doesn’t support all types of JPEG images, and I there stated a little more of my findings of why you get that message: Pure Java alternative to JAI ImageIO for detecting CMYK images