Tips for making good high resolution scans

If you want to scan either your own personal art and digitize it for printing, or want to scan/enlarge vintage art for digitizing and/or printing, here are some tips you may find helpful.

First: if there is any digital retouching to be done, do it before you scan–not after. Save the digital file in .tif, not .jpg format, and print it out on the very best printer you have available–preferably laser as opposed to inkjet. (If you are scanning from a physical piece of paper, then obviously this does not apply).

If you only have an inket printer, make sure you print it on matte, not glossy, paper. Go into your printer preferences (rightclick your printer in your control panel) and set the printer on its highest settings (ie resolution).

Now, I have heard it said that when you get into the high range DPI arena, that there is no difference between 1200 DPI and, say, 3600 DPI. Bah-lone-y. Don’t believe it, because it’s simply not true. I have done extensive testing and comparison between the various resolutions, and there is indeed a marked difference between a 1200 DPI and 3600 DPI scan.

If you are scanning a relatively small image (postcard size) as opposed to a larger image (8.5 x 11 size), then you’re going to need every extra pixel you can grab–so go as high resolution as you can. If your computer has the RAM to handle it, scan those small images at about 3600 DPI, or, at the very least, 2400 DPI.

If your scanner has a relatively sophisticated interface, try and configure it if you can by setting the filters to minimize noise, and set the levels (darkness and lightness) by sliding the bar to where the image has the best contrast level. If your TWAIN interface is old or doesn’t offer any filtering, try some of these free TWAIN downloads.

Make sure your scanner’s glass is clean with every use; I use lens cleaner pads. You can also use a soft rag with alcohol. Make sure your print is as even/straight as you can make it–the last thing you want to do is fuss with rotating it around in Photoshop, so avoid that if you can.

After your scan is finished, open it in Photoshop. Depending on the amount of RAM your computer can handle, this can take anywhere from a couple of seconds to many minutes. (To increase the amount of RAM assigned to Photoshop, go to your edit > preferences panel. Also make sure you have at least one scratch disk assigned to Photoshop, ie, a drive other than “C” upon which Photoshop can write temporary data. (I have five scratch disk drives, but most people probably won’t need that many!) This will help speed up Photoshop during heavy duty RAM-sucking jobs. To add a scratch disk, go to edit > preferences > performance, locate the drive you want to use a as a scratch disk and assign it there.)

Look at your scan in 1:1 size. You will see dots, or a moire pattern. There are a couple of ways to get rid of this. I do two things. First, I go to filter > noise > median and adjust the sliding bar until the moire, or dots, blur or dissapate to my satisfaction. Every image will be different, but for extremely large scans I find “5″ a good median number. For added power, however, I use a nifty noise reduction program aptly called “Neat Image.” You can use Neat Image as a standalone software or as a Photoshop plugin.

Don’t forget to embed a color profile in your image. Most popular is sRGB, which is the standard color profile. I use Adobe 1998, which does tend to pump the color up slightly. Go to edit > assign profile in Photoshop. Resave.

Whatever you do, make sure you save your scan in .tiff or .psd format–never .jpg. Jpgs are for web use and quick loading; to prevent loss of data, it is not the proper format in which to save high resolution files. Remember, every time you open and re-save your .jpg file, you lose data. Every time. So make sure you only use .jpg for emailing, web use, etc.

Save your original, untouched scan on a DVD disc.

Questions? Problems? Let me know!