removing background from a scanned text?

Comments and discussions about Adobe Photoshop
Post Reply
Plugin Guru
Plugin Guru
Posts: 3360
Joined: Fri Mar 08, 2002 1:00 am
Location: The Plugin Site

Post by HaraldHeim »

I usually do that by increasing the contrast. As you have images in the scanned page, you may need to mask them out before applying the contrast adjustment.

Plugin Novice
Plugin Novice
Posts: 3
Joined: Thu Jul 05, 2007 2:24 pm
Location: West Virginia, USA

removing background from a scanned text?

Post by wvperegrine »

I think I have a way that preserves more of the subtleties of most typefaces, if that's important to you. Harald's is the easier way, for sure.':D'

Sounds like what you're dealing with is what old scribes like me call "illuminated text," with embellished capital letters. I've used the following technique to enhance scanned blueprints and scanned calligraphy on faded paper, for example, and I've done it mostly in Photoshop. I think you can do so in The GiMP, Paint Shop Pro and perhaps in other programs of this kind. I'll describe it in Photoshop 7.

With the image open, go to Select > Color Range ...

A dialog box opens, displaying your scanned image and some options

In the dropdown menu labeled "Select:", choose "Sampled Colors"

Now, when your cursor is hovering over the image in the dialog box OR the original image, the cursor will look like an eyedropper. Use the cursor to select a color in either window by clicking on that color (in this case, I would choose the background color of the page, which may range anywhere from off-white to rather badly yellowed)

You can fine-tune the selection by adjusting the setting called "Fuzziness" in that dialog box. I sometimes have to "undo" a few times until I get it right. If you like, you can zoom in on the text to see how well it's isolated from the background (and whether you're losing detail in the serifs, etc.) If necessary, you can use the "quick mask" to help you touch up things like water spots or coffee stains on the paper.

When you're satisfied that you've selected all the background, but nothing important within the pictures (that could be the hard part), go to Edit > Fill ... and again, a dialog box will open. In this box, what I often do is Use:"White" in the dropdown menu under the "Contents" section, and set "Blending" to something like 90 or 95 percent opacity. This way, you actually retain (but greatly reduce) a little bit of the texture and other detail on the page. You may get better results using an off-white or even pure white "fill" without any blending at all, so don't be afraid to experiment a bit to arrive at something that will work for all your scans of this type.

Sounds complicated, but it really isn't, and with a little practice it gives better results than other methods. Good luck!

Plugin Power User
Plugin Power User
Posts: 6
Joined: Sat Jul 05, 2008 10:52 am

Post by Jen0608 »

Good advise wvperegrine...I think that's help a lot especially to those like us newbie in photo editing...Anyway practice makes perfect...

Plugin Guru
Plugin Guru
Posts: 298
Joined: Tue May 31, 2005 11:02 pm
Location: LA area

Post by plugsnpixels »

I usually do a simple Levels tweak... ;-) Pull up the whites or mids.
Free digital imaging ezine (and discounted plug-ins!)

Post Reply