Making Raster Scans Look Good

You've probably been there already. You have a client that want a picture on his homepage, but the only version the client can find is from their old marketing material. The guy/advertising agency that did the brochure has ceased to be or had a nervous breakdown, or... There is no chance of getting the original picture from anywhere. So you turn to your client and tells him you can fix this with your trusty friend, Adobe Photoshop.

So you get the brochure, and if you're lucky, its not crumbled or anything, its just hard to get a decent scan out of.

Well, here is a trick to make it easier for you and make great looking results with Photoshop and a scanner.

Personally I always scan at least 200% more than what I need (if I need to scan for another print job, the print job usually requires 150 DPI, so I go for 300 DPI) For screen resolution its best to go 300 DPI at least as well. 

Then I throw in a bit extra, and usually ends up at 500 DPI. It of course matters on the quality of your scanner. Most scanners can emulate a much higher DPI than they can actually scan, but I will show you how to come up with a decent result even with a cheap scanner.

The trick

Here is a cut-out of the original picture. Horrible quality which will look even worse if we had to use it for print gain.

Step 1

Scan the image in obscene resolution and start Adobe Photoshop

Step 2

Slightly blur the image using Gaussian blur. Never go higher than 1,0 in the settings, otherwise the end result will look very blurry. Most of the time a setting around 0,7 will do the trick.

Step 3

Change the image size. Not by a lot, we have to repeat step 2 and 3 a few times. If the image width is 2000 pixels, try to take it down to 1900, using Bicubic re-sampling (default setting).

Here is the same area after this first repeat:

This is after the first repeat. It's not incredible, but its definitely better. Lets see what happens if we repeat above step 2 and step 3 a couple of times, varying the settings slightly by each step.

This is after a few repeats of step 2 and 3. You can hardly see the remaining raster any more.

Here is the final result. For good measure, I always edit the image slightly after using this trick with some brightness/contrast settings and a bit of levels (CTRL-L).

I hope you find this little trick helpful.