1) Chips are 3-dimensional and scanners are only 2-dimensional. The 1/8" depth of casino chip causes shadows that are sometimes difficult to crop out, especially on dark chips.

2) Scanners have a moving photo element, it causes a slight distortion in the scan, maybe 1 or 2 pixels on a chip size of 240x240 pixels. Also on one of the chip edges the scanner will show nothing of the side (depth) of the chip, while on the opposite end you will get the full edge. I can crop the sides out, but it makes the job tougher. With a camera and macro lens, I can get a flat image with no sides and no noticeable distortion.

3) Some scanners have a tough job with color rendition, especially orange and other "hot" colors.

4) Some chip scans lack details (like cross hatching) due to difficulties with color rendition. While one chip can come out sharp, another chip will come out dull with exactly the same scanner settings.

Don't get me wrong, my scanner generally does a great job, but there are some chip scans it produced that I feel would look a lot better with a proper digital camera set up.