If you scan your own artwork in preparation for making giclee prints (or enabling prints-on-demand on a website), you probably already take care to adjust the colors with Photoshop to ensure the digital and printed images are as identical to the original as possible. But there’s one more step you should take with that scan: remove dirt specks.
Of course you carefully cleaned the scanner bed before you laid your artwork face down on it, but there were undoubtedly specks you couldn’t see. Furthermore, the artwork itself probably attracted specks of dust during the time you worked on it. Some of them may even be embedded in the medium. When you scan at resolutions upward of 400 or 600 dpi, it’s very easy to see these specks by zooming in on the scanned image in Photoshop.
Fortunately it’s very easy to remove them, too! And you should–you want a giclee print to reproduce your artwork in all its glory, not the specks of dust and dirt.
After you have done any straightening, cropping and color-adjusting in Photoshop, zoom in, way, way in, and look for those little black specks. Select the “Healing Brush” tool and set its diameter to just barely big enough to encompass a speck. Click on the speck, and voila, it’s gone. Photoshop uses the color information around the speck to interpolate the color that should be there instead. You want to use as small of a “brush” as possible to avoid detail loss. When I’m zoomed way in, my “brush” is often only 4-6 px in diameter.
The “Healing Brush” is the same tool that photo restorers use a lot to clean up old photo prints. Many newer scanners have a “dust removal” setting that can be turned on during the scanning process, but I don’t trust them; suppose you have fine dots or very delicate details in your artwork–you don’t want the scanner software to remove them!
I hope this helps you produce better prints of your artwork.