My very old relisys scanner worked perfectly--but only did scans. I could also adjust the picture many more ways than I can my 2 NEW ones.
My new Dell AIO scans just like the one you have, but my Cannon Pixima MP780 does all colors perfectly. It seems to be the drivers that come with the scanner/copiers (my Dell will also not copy these colors, but WILL print them if scanned from another source). I have talked to tech support at length (every day, several hours a day for months) about this problem, and there is nothing that they intend to do to correct the drivers.