When uploaded to the Documents and Media, some JPEG images produce a thumbnail with wrong colors, i.e. a pinkish shade instead of white.
Other tools (e.g. Jira & The GIMP) open the image properly with not even a warning. After re-saving the image with GIMP, it uploads as expected. I found no EXIF or IPTC metadata (using the exiv2 tool). Having debugged a simple C program linked against libjpeg, the original and the re-saved images differ in their color space: JCS_RGB and JCS_YCbCr, respectively. Eclipse SWT suffered from the same issue in 2006: external link.
The related Portal code is ImageToolImpl's read(byte, String) method. It utilizes the somewhat old third-party JAI to decode image data.
I attached an image that produces the issue on trunk.