I took pictures from my old Nikon D40. I converted them with the standard settings from NEF to DNG.
I then used UFRAW under Linux and saw that the pixel size increased from 3039x2040 in NEF to 3040x2040 in the DNG - and that the live view RGB values were about 5% higher for NEF that for DNG.
"FastStone Image Viewer" shows the same increase in pixel size. Additionally, it shows that the DNG has roughly 93,000 unique colors compare to 90,000 for the NEF file.
More pixel, different RGB values, different counted unique colors - what's going on here? This doesn't look like a 1:1 conversion?
Not exactly sure what you're comparing. For raw data you need to be comparing the original mosaic data values (not some converted result, or even partially converted result like demosaiced result). Are you sure that's what you're doing?