To test the ability to output solid colors, I created a GIF file (shown below) containing 256 squares of different colors. (I'm guessing the number is 256 -- it could be a bit fewer.) To download this file, click of the right mouse button and choose the "Save As" option.
I printed this graphics file at the size of 6-7/16" x 5-1/4" which is exactly 57-1/3 dpi. I know...it sounds pretty arbitrary. The reason for all the weird numbers is that I did the layout with Sierra Print Artist. Print Artist printed it to those dimensions listed about but exported it to a size of 367x301 pixels. (57-1/3 dpi x 3 = 172dpi, perhaps this number has some significance?) The output was then scanned on a HP IIc at 150dpi with maximum sharpening enabled to capture the dithering.
In terms of printer setup, I used 1440x720 dpi, error diffusion and ICM color matching on Epson Photo-Quality Coated Paper. I experimented with a few other options but orange kept coming out as red. (You may wonder why I didn't use ICM in the photo testing section. Well, I find less accurate color matching often produces better results; in other words, fantasy usually looks better than reality.)
Onto the results:
|Orange, Green, Purple|