Re: [Gimp-user] Need help repairing image

["Ronald F. Guilmette" <rfg tristatelogic com>]

In message <4EF8950F 6050406 pilobilus net>, 
Steve Kinney <admin pilobilus net> wrote:

> You won't find a "one tool" or "one filter" solution for this one. 

:-(

> This is a fairly major project.  However, rest assured it can be
> done; check out the first image on this page: 
> http://pilobilus.net/photo_rework.html  It's far from perfect but
> not bad for something I did ten or so years ago with an earlier
> version of the GIMP, and demonstrates something of what is possible.

Yes, those are some impressive restorations/enhancements.  Obviously, the
first one (baby with streak) is most applicable to what I'm up against.
Can you recall the specifics of how you tamed the streak?

> You face three problems:  An unwanted color, an unwanted darkening,
> and loss of detail.

Having come here seeking help and admitting that I'm a Gimp novice, I
really shouldn't do this, but...

I'm going to take issue with one small part of what you just said.
Specifically, the last part... loss of detail.  Yes, there is serious
discoloration, and yes there is serious unwanted darkening (and probably
also loss of contrast & saturation).  But from where I am sitting, it
appears to me that underneath the green streaks there is very nearly
just as much detail as in other similar parts of the image.  (Embarassingly,
as all can see, the background mountains and snow on this shot were all a
bit out of focus, so the background level of detail isn't all it could
have been or should have been.  But the point is that there appears to me to
be the same level of detail still there, even underneath the green stripe.)

> First, save your original image as a .xcf file...

Thanks!  That's obviously a good suggestion, and is something that I had
not thought of or known that I should do.

> You might want to start by doing what you can with filters. 
> Duplicate your base layer, and select the damaged area.

Sorry, you lost me already. :-(

"Duplicate base layer"?  I dunno how to do that.  (Time to hit the manual
pages, I guess.)

> Turn on
> your Colors > Hue / Saturation tool, click on the image, and in the
> dialog box that appears, select green and dial the saturation down
> and brightness up until most of the green disappears.  This will not
> fix the image but it carries you part of the way there.

OK, but as you can see, the green stripe is lighter to the left, and darker
to the right.  So if I just select that whole stripped area and then start
fiddling things, correct me if I'm wrong, but won't that likely create some
result that is less than optimal for each of the two sub-sections of the
stripe (i.e. the lighter part and the darker part)?

> Then you might want to "select none" and get busy with the Clone and
> Smudge tools, painting in replacements for the "lost" areas, guided
> by (but not strictly limited to) the content of the partially
> restored area.  This is what I managed in three or four minutes,
> nowhere near done of course:
>
> http://img850.imageshack.us/img850/4571/img001justastart.jpg

That's really pretty darn good, I must say.  And your example makes it quite
clear and apparent that the image could be repaired this way, at least to a
presentable state, even if not in a way which is completely faithful to the
actual original (undamaged) image.

I guess I have a bit of an uneasy feeling about the whole notion of
``painting'' the image, you know, as opposed to simply lightening and
changing the color & saturation on parts of it.  But to be clear, it's
not that I am in any sense ``morally opposed'' to the notion of painting
parts of an image, e.g. to eliminate undesirable image elements altogether
(as you did with the ugly heating vent in your belly dancer shot).  In
fact, I've already used Gimp on another on my old negatives to do exactly
that, i.e. paint out a thing in the image that was just distracting.

But in this shot, the mountains and the snow _are_ really one of the main
subjects of the image... not an unwanted distraction.  And as I've said,
from where I'm sitting, there is still plenty of _real_ underyling image
detail (under the green stripe) that I would sort-of like to preserve, if
possible, rather than just paining over or replacing outright with other
little chopped up parts of the undamaged background or, God forbid, my
own clumsy attempts to hand-paint in some details.  (I am as clumsy with
a brush as The Hulk is with a sewing needle.)

Along those lines, I want to come back to what I think I mentioned in my
original post regarding this image... I have already gained some experience
with (and already achieved some good success with) the dodge&burn tool.  I
used that tool to great effect on one old black&white image I had where a
significant and large portion of the image was very washed out, for some
unknown reason.  (Again, it may have been simple degradation of the negative
over decades in storage.)

The dodge&burn tool allows for gentle alterantion of the brightness level of
(hand) selected parts of an image, and I know that in careful hands it can
be applied in a way that makes its use essentially undetectable, i.e. no
visually apparent edges between the ``treated'' part of an image and the
untreated parts.  (Doing this well is quite obviously ``art'', and it is
sort-of like painting, but different in that the underyling image detail is
perserved.)

So anyway, for my mountain camping shot I really really really wish that I
had a set of three things that, in a sense, would be just like the dodge&burn
tool, except that rather than supporting selective and gradual altering of
the local brightness level, these hypothetical new tools would allow selective
and gradual altering of (1) the local contrast and (2) the local color satu-
ration and (3) the local hue.  If I had those three kinds of tools, then I
think that I could clean up this image of mine in no time _and_ completely
preserve all of the detail that is quite obviously still there, underneath
the green streak.

Are there really no such tools in the Gimp toolbox??  If so, I'm frankly
flabberghasted by those ommissions.  I mean to me these seem like such
obviously (and widely) useful things.  And above and beyond that, I mean
geeezzzz!  Gimp seemingly already has *everything* else, *including* the
kitchen sink!  (So to me it just seem a bit odd that it wouldn't also
already have the tools that I just now dreamed up.)

So perhaps one question I should be asking is:  Where do I go to appeal to
the current Lord(s) of the Gimp for the addition of exactly such new features?

> As always, there are MANY ways to do things, and you might be able
> to come much closer to a final repair by using multiple layers,
> gradient masking, colormap rotation and other advanced filters,
> etc.; but the above will at least give you lots of exercise with the
> clone and smudge tools, brush usage, etc., and will (eventually!)
> give you an image that looks good.

Can you please elaborate on any or all of the above, for the benefit of this
Gimp novice?

I understand only a bit about layers.  Should I be separating this image
into red, green, & blue layers and then be attempting my repairs primarily
or exclusively on the green layer?

Also, if you could give me a one sentence definition/description of "gradient
masking" I'd appreciate it.  I have no idea what that is.  (You don't have to
dumb it down all of the way to baby talk.  I actually worked as a photographer,
briefly, once upon a time in the very distant past, so I grok at least basic
image/imagining nomenclature.)

Ditto for "colormap rotation".  What is that, exactly?

With regards to the clone and smudge tools, I haven't actually delved into
those myself yet, but I'll go off now and read up on them.  I know where and
to find the relevant ``man pages''.

> For a beginner this is a fairly major hobby project...

I was hoping not.  And like I say, I do believe that if I had dodge&burn
equivalents for contrast, saturation, and hue, I'd have already cleaned up
thsi image, toot sweet.

> ... bear in mind that the objective at this stage is
> not an image that "is right" in the sense of an exactly faithful
> reproduction of the original scene, but an image that "looks right"
> in the sense that it conveys the general appearance of the scene to
> the viewer.

Yes.

Don't get me wrong.  I'm not a historian or a historical archivist/purist.
If it ends up that I have to effectively cut&paste other undamaged parts of
the mountains and snow over the damaged parts, you know, in order to end up
with a passable image, then that's what I'll do.  But as of this moment I'm
still holding out hope for some solution that is a bit more elegant (in the
sense of doing less violence to the actual undamaged original image details).


Regards,
rfg


P.S.  A question to the general readership of this list:  Does anybody else
agree with me that having dodge&burn-like tools that would selectively and
locally alter contrast, saturation, and hue sounds like a Good Idea?

Even for black&white, imagine being able to use, for example, one of the
airbrushes to delicately ``paint on'' higher or lower contrast in certain
select portions of an image.  (Personally, I think that would be pretty
bleepin' cool.)