Greg,
Yes, I think you're both right. This printer has the ability to print not only on paper but on T-shirt transfers and transparencies. I suspect that is where the halftone screens are used.
I also suspect the 'grain' I see in my prints is actual film grain. It might be time to start using the correct film instead of whatever's handy.
The easiest way to determine if the "dots" on your print are grain or not is to look for uniformity or lack thereof. (Finally got to use "thereof" in a sentence!) Grain will of course not be uniform, inkjet dots will. Problem might be a combination of both - which would make it a little harder to differentiate between them. Pixleation generally means you start seeing actual square pixels in your print. And also anything that looks like 'dots' on screen will generally be part of the (original) image whereas pixels will be square, if you zoom in on them. Pixels = resolution which means just scan at higher res. Photoshop has several ways to view an image, one is at Print Size (View>print size). This displays the image on screen at its physical size. The other could display 'Actual Pixels'. 'Print size' view would obviously be much smaller if the image is at a high res. where 'Actual..' would show the image at 72 ppi making it much bigger and easier to see the flaws, whether from original, scan or file problems. HTH.
Norman
