Re: [Gimp-user] dotted areas, how to erase (or change)

[Liam R E Quin <liam holoweb net>]

[sorry if you get this twice, sent from wrong account]

On Tue, 2012-02-28 at 06:52 +0100, mamboze wrote:
> I've got a problem editing an image with a dotted background in it. By
> 'dotted', I mean an array of small evenly spaced black dots on a white
> background. 

The most common cause for this is that it was a printed image that
someone scanned, and the dots are what's called a screen.

There area number of descreening algorithms. Some scanners can do this
fairly effectively.

I often try scanning at 1200dpi or 1800dpi, then doing a gaussian blur
with a radius of between 11 and 19 pixels -- increase in the preview
until you can't see the grid at all, then add a couple.

Then afterwards scale the image down a lot, e.g. to 20% or even 10% of
the original scan, and use filters->enhance->sharpen.

Select the rectangles with text in them, and copy them to a separate
layer first, bcause they probably don't want blurring.

Liam

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org www.advogato.org