Hello;
I'm new to the Gimp forum. I took a quick look at the archives and decided to try a more direct approach. This forum.

Wanted: In Gimp, to add (SUM) the RGB values for a pixel and then change all pixels who's RGB SUM is greater than a user stated value to WHITE.
Second side of that is to change all RGB SUMs less than value given to Black. BUT not doing both at same time, thus allowing user to "step" in and see what got lost.

Anyone who has scanned old CAD/Architectural files and prepped them for Raster to Vector conversion will know intuitively my intent and reason for wanting this ability.

Yes - I can do this with another program but it means "sending" the file back and forth and working "blind". It would be nice to have it "in" GIMP.

While I can program, I have never tried using Gimp's language. The docs I have seen on the subject are not very clear to someone new to the language. Nor did I find any "clearly the Gimp's verbs (functions) and their syntax" anywhere. Again, I scanned the 'HELP' and Gimp.org site and then came here. At the very least someone should be able to point me to the "real stuff" much faster than me trying to wade through HTMLs. (Grep doesn't like them :)

Steve norseman@hughes.net

Sven Neumann wrote:

Hi,

On Tue, 2009-06-23 at 14:51 -0700, norseman wrote:

In Gimp, to add (SUM) the RGB values for a pixel and then change all pixels who's RGB SUM is greater than a user stated value to WHITE.
Second side of that is to change all RGB SUMs less than value given to Black. BUT not doing both at same time, thus allowing user to "step" in and see what got lost.

Use the Levels tool. That is pretty much exactly what you achieve by moving the Input levels in the Value channel (except that Value is not defined as the sum but the max of the RGB values).

Sven

======================
I have been trying exactly that 'macro'. It does not work as expected. I'm using Gimp 2.6.6 on Windows XP Pro. Using a Twain32, Gimp makes a great scanner input system. Most files DO clean up quite nicely with Levels, but some need more direct control. As it has been programmed, Max is NOT SUM, unfortunately. Question is how to get Gimp to do what is needed?

Steve