I hurriedly photographed the text in a greeting card and have uneven lighting
and underexposure that I'd like to correct. Please see attachment, in which I've
increased the brightness and contrast and then desaturated. This helps but it
needs lots more!

I've looked at tutorials on gradient contrast masks but I get lost part way
through. Either I'm too much of a newbie to understand (highly probable) or
maybe the tutorials are for older versions of GIMP. (I'm on 2.8.6 for Windows.)

I am very grateful for any advice anyone would care to offer!!!

Use the Colors->Threshold tool

It maybe necessary to use the select tool and make various selections and then apply the threshold tool to those selections

use a brush and paint white to clean up any odd spots

See http://members.pcug.org.au/~rcook/images/threshold.png as a quicky

Owen

On 07/20/2013 03:57 AM, billlee wrote:

I hurriedly photographed the text in a greeting card and have uneven lighting and underexposure that I'd like to correct. Please see attachment, in which I've increased the brightness and contrast and then desaturated. This helps but it needs lots more!

It woud be easier for us to have the orjginal...

I've looked at tutorials on gradient contrast masks but I get lost part way through. Either I'm too much of a newbie to understand (highly probable) or maybe the tutorials are for older versions of GIMP. (I'm on 2.8.6 for Windows.)

I am very grateful for any advice anyone would care to offer!!!

Many techniques I have seen stat by duplicating the image then applying a very wide gaussian blur to it, then playing with layers mode between the to images: for instance, the blurred layer on top, in "divide" mode, makes the paper uniformly white.

I am very grateful for any advice anyone would care to offer!!!

Hi!

As already mentioned, there are several ways to correct such things. To equalize the brightness levels you could use my tutorial here: http://www.gimpusers.com/tutorials/equalize-homogenize-brightness

After that you'll get something similar to the attachment: "equalize". Apply contrast now using the levels tool (Color / Levels) and move the rectangles as seen in the image: "levels". The final result will be an image with mostly white background and well readable text.

Hope that helps!