I recently bought an Epson Stylus Photo 700 printer, but have been unable to reproduce "photo-quality" prints from my scanned photographs. The colors are OK, but the prints don't have the detail or crispness of the originals. I currently scan photos at 300 dpi using an HP ScanJet 5p scanner and print them out through Photoshop 4.0. Do you think that maybe my problem could be with the scanner rather than the printer? Perhaps I need to scan at a different resolution? I've had some suggest that I scan at 240 dpi, while others have suggested 480 dpi. Any suggestions (scanning or printing)would be appreciated. Thanks.

-- Colin Gildea (cgildea@ameritech.net), February 22, 1999

Answers

I have the original Epson Stylus Color that prints at 720 DPI. I found that printing a 1280x1024 image at 10x8" seems to work pretty well. That works out to about 128 DPI of image for every 720dpi of printer capability. I'm guessing that ratio or maybe double since your printer can print 1440dpi might work for you. Bear in mind that your printer may be rated for 1440 dpi, but I believe thats in the horizontal direction only. I think it's still limited to 720 dpi vertically. Further, the DPI rating for the printer is not equivalent to the DPI rating for the photo. The reason for this is that a printer dot can only be black, white, magenta, cyan, or yellow(maybe a few more colors for those who have more ink colors) and a pixel in the photo can be any one of 16.8 million colors, generally speaking. By scanning at a lower resolution and printing at a higher one you allow your printer to use more dots to represent each pixel in the photo which gives each pixel a greater range of color. TRY IT!

-- Gerald Payne (gmp@francorp.francomm.com), February 22, 1999.

I agree with Gerald's comments, and add these:

Whenever you scan something, the scanner pixels are basically "averaging" the image data over a given area. Same thing happens on output, as Gerald explained, with the individual ink dots either being on or off, and multiple dots being needed to build up various tones and colors. This amounts to an overall blurring of the image relative to the original. This effect is the very reason the "unsharp masking" process was developed, going way back to the early days of printers halftones. In Photoshop, try playing with the Unsharp Masking filter (Filters/Sharpen/Unsharp Mask), and see what you find. You'll probably have best results with relatively modest amounts (100% or so), but play with the "radius" setting to see what looks the best. The appropriate setting will noticeably sharpen the image, without creatingn "halos" around the light and dark edges. Try a run with a large percentage and huge radius (10 pixels, say), to see what way too much looks like, then dial it down from there. Also, the radius that works best will likely be a strong function of output scale, rather than pixels on the original image. Thus, a smaller image scaled larger output would want to have a smaller radius. Unsharp masking will make a HUGE difference in the sharpness of your output! Good Luck!

-- Dave Etchells (hotnews@imaging-resource.com), February 25, 1999.

Colin, Your biggest problem is your scanner. The HP Scanjet 5p is a good value (he said never having used one) but youre asking it to do too much. Reflective scanning is always a last resort for photo reproduction, just as taking a picture of a picture yields a fuzzier copy than the original. A drumscan (transmissive  using slides or negs) is still the only way to go for the best results, and even that wont match the original...And is expensive.

The unsharp masking as suggested by others is a big help. You really need to experiment with USM alot to really learn it. You have four variables: the three parameters in the filter (Amount, Threshold, Radius) and the quality of the image to start  images with low resolution or poor quarter-tones dont unsharp mask very gracefully.

-- Jim Scott (wgd@napanet.net), March 06, 1999.