Re: [Gimp-user] threshold function parameters that vary by position? (going to B&W from a book page photo)

["Owen" <rcook pcug org au>]

> Hello,
>
> I would like to obtain a black and white image of a photograph of a
> book page.
>
> My attempt to do this is by running the threshold function over the
> entire image.  This appears to give the desired result, but only
> locally.  It appears that the optimum parameters of the threshold
> function vary by position (i.e., according to some scalar field), with
> one extreme in the center of the glare and then radiating outward.  So
> just running the threshold function over the entire image with
> constant parameters always gives sub-optimum contrast for 75% of the
> image.  Will I have to find a way to run the threshold function with
> non-constant parameters, or is there some other tool to do the job?



Without seeing the image, one can only suggest you try converting the
image to Indexed and 2 colors.

You could also leave it as rgb and play with the curves, maybe one of
the colors can be filtered out.

If you get a good B & W image, you might then want to run it through
the unsharp mask to improve the text.


 --
Owen