When creating a PDF using PDFBox and drawing PDJpegs to it, the images' colors are changed / inverted when resizing the PDJpeg(s) before drawing them to the PDF. This issue is only visible on Windows XP and Windows 7 using e.g. Adobe Reader. Preview on Mac or the new PDF preview build in Windows 8 are somehow not affected by this.
I tried it with PNGs and JPEGs, Colorspaces sRGB and CMYK, with and without alpha channels. But the issue is the same with all image types.