How to get better scans

Removing margins, extracting type

Prakash from GU, India, using Photoshop CS with XP Pro, writes in with:

[Quote:] I have a couple of problems and a solution would be welcome. 1. I have images scanned with white margins on scanner. So I would like to know if I can crop the white margins in some way. The auto crop tool only crops BLACK margins. 2. The scanned images have writings on them. Now many images have ink which has come over on the other side. Further, some have printed text which has come in reverse on the other side. Is there some way I can lighten or remove such marks? I am scanning the documents at 300 dpi in color 24bit. I would want the original text to darken while lightening the paper color? Is this possible? Thanks in advance for a positive reply.

Reply:

Okay, let's tackle these problems one at a time:

1) Eliminating Margins

Your scanner software should have a selection rectangle where you can manually select just the areas you wish to scan -- thus eliminating the margins. If the images are scanned with the margin, then you'll have to use the Crop tool to crop your image. (You can also use the selection marquis to select the live areas, then use Edit > Crop to crop out the margins.

2) Eliminating "Show Through"

The condition Prakash refers to in "come over on the other side" is called "Show-through" -- which is a severe pain when you want to scan from the newspaper, yellow pages or magazines printed on thin paper.

This is a delicate tight-rope walk when trying to eliminate show-through while maintaining vivid and saturated image of the image.

First, try to select ALL of the vague markings along with the PAPER by using the
Select > Color Range command.

Set the 'fuzziness' to a low number like from 8 to 32. If it grabs too much of the "good" image areas, you'll have to turn it down.

Now, with that selection active, set a new layer, Tap "D" (resets colors) then Tap "X" (makes White the foreground color) and Alt/Delete. (Mac: Option/Delete).

This replaces the paper with white on a new layer, and thereby should knock out all the gray areas from zero to about 20%. If this did not knock out the Show-through, go back to the scan layer and select specific gray ranges. Be careful not to select image you wish to keep.

This is the best way to accomplish what you wish.

Another method is to select and then mask the "good" areas of the scans you wish to keep. Do this by using an Adjustment layer and increasing the Contrast slightly. This will have the effect of making the blacks blacker and the whites whiter. However, if there are photos involved, you may want to select those using the Lasso or Marquis tools, and raise them to their own layers so they won't be affected by the increase in contrast. If the color subjects or photos are rectangular, you've got it made.

Once you're affecting only the typography on the page... assuming it's black or a dark color, then you can substantially increase the contrast and brightness and knock out much or most of the show-through.
KEYWORDS . . .

Comments

[Keith]

You can also play with the contrast level that your scanner is using to make the blacks blacker and whites whiter.

[aman]

thanks that helped a lot .

[Jarvis Grant]

To handle the "Show Through" problem, there is an easy fix. Place a black sheet of paper on top of your copy. This will reduce the image on the other side of your scan from coming through. This is an old trick used by photographers when copying text or page illustrations from a book.