Re: [Gimp-user] how to darken bright areas

[Steve Kinney <admin pilobilus net>]

On 01/04/2017 06:58 PM, paulhurm wrote:

> For others who may read this, again, I need help on how to work with the current
> scans I have. I am also not willing to do any re-scanning since some of the
> captions seem to be deteriorating and I don't want to handle the pages any more
> that is absolutely necessary.

You are up against an intrinsically difficult problem; restoring the
photos to their original condition is not possible, and making them
"look like" they were restored to original condition would amount to
using them as guides for creating new images from scratch.  But making
radical improvements is not especially difficult.

I did the following things with the image you provided:

1)  Converted it from indexed to RGB mode.  Indexed images do not work
and play well with filters.

2)  Saved it to XCF, created a duplicate as a new layer and named it
"white balance."

Then I had a go at correcting for the overall fading, with the Levels
tool (Colors > Levels, or add it to your toolbox buttons via Edit >
Preferences > Toolbox).  The histogram is cut off at both ends, which
might be an artifact of destructive compression by the scanner or some
program used to process the image.

I used the draggable markers at the bottom of the Input Levels display
to set the black point to 50 and the white point to 235.  This has the
effect of "stretching" the histogram from true black to true white.
Then I moved the mid-point marker to the right, and settled on 0.45, as
a "natural looking" adjustment.

3)  Then I created a copy of the corrected layer, and tried a few items
from the G'MIC filter pack.  Repair > Smooth [median], with a radius of
five pixels, knocked the sparkly silver clumps way down with minimal
degradation of "wanted" image content.

4)  Then I added a mask to the filtered layer, and painted on it in
white to bring back some lost resolution in areas with important details
(faces, hands, etc.) and, switching to a smaller brush and black,
painted on the mask to wipe out some bright specks that were restored
along with the "wanted" details that were softened by the smoothing
filter.

5)  Finally, I created a new layer as a copy of the visible image, set
its mode to Multiply, and dialed its opacity down to 33%.  This brought
the contrast way up.

Result:  http://pilobilus.net/xfer/p48_TEST_GRAY-EDIT.jpg

There is still room for a LOT of corrections, and someone may come up
with fundamentally better ideas than the process outlined above.  But
it's a starting point of a sort, at least.

:o)

Steve