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Photo retouching with GIMP
by Luis Vinay

Q&A

Before we start I must answer some very common questions

Q. Where can I get GIMP?:

A. The GIMP project has a version for almost every platorm (what a cool guys!):
- If you use a GNU/Linux (like me) or any kind of Unix based system go to: http://www.gimp.org/downloads
- If you use Mac OS X you can go to: http://www.gimp.org/macintosh/
- Finally if you have the missfortune of using Window$ go to: http://www.gimp.org/windows/, just a joking ;-)

Q. Why a tutorial about GIMP and not about Photoshop?

A. There are many reasons, one very strong it's and very simple: Because I can.
GIMP creators want that anyone have access to their software in contrast to Photoshop creators who doesn't, they want that so badly that the give it away completely free, you're free to use it, copy it, modify it and redistribute it.
That's are pretty good reasons, aren't they?

Hand's on!

(F-15) For this tutorial I took three common cases that we can encounter everyday, the first one it's a picture taken under poor and unadequate light conditions, with this image I'll cover the basics of tint, brightness and contrast correction.
On the second case the problem it's more subtle, the problem here it's a bad election of camera settings, with some more tools we can bring new life to a dull picture.
The last case the problem it's the overexposure of the image, a more advanced usage of GIMP allow us to improve the picture othrewise unusable.
For all three cases you'll get the link to download the starting pictures at the end of this how-to.

Case one

As you can se here, I'll leave a the left of the screen the staring picture for you to compare the results.
[retouch_screen-1]


Now, go to the Colors --> Hue-Saturation menu, you should get a screen like this one


Select the "Y" and move the Saturation slider down to "-40", you'll notice right away how much the image improves with this simple change.


Press "OK" and Compare now both images



Now, we'll correct a bit the lighting, go to the Color --> Levels menu, you will get something like this



Move the white triangle below the graphic to the left as here


Press "OK". That's all, compare both images and see how with this two simple adjustments you've got a much better image.



Case Two

Let's start here


Go to the Color --> Levels menu and move the white triangular slider to about a "186" value


With just this modification, the improvement it's very noticeable, but we won't stop here


Now, go to the Colors --> Hue-Saturation menu, select the "C" (cyan) and move the slider left to about a "-30" value, a sublte but interesting change


Our final adjustment will be raise up the contrast, to do that go to the Colors --> Brightness-Contrast menu and move the "Contrast" slider to something like a "16" value



Case Three

Here we will tacke the opposite problem than before using the same tools, also I'll leave the starting image a the left of the screen for comparison purposes.
Let's start, open the image with GIMP and go to the Colors --> Hue-Saturation menu


Now, select "Highlights" and move all the three sliders down to "-25", you'll notice a subtle difference, like here


Then select "Shadows" and again move all the three sliders down to "-25", now the difference it's much more noticeable


Go to the Color --> Levels menu, do you see a familiar situation?, as you can predict we're going to move the white triangular slider to the left just where the graphics ends


We're almost finished, perhaps you can notice that the color got a little odd or over-saturated, don't worry, we can fix that, Go back to the Colors --> Hue-Saturation menu, select the "C" (Cyan) and move the "Hue" slider to the right a little bit I wen't to about a "+11" value


This exposed a too brighter red, so select the "R" and move the "Saturation" slider to a "-25" value.



This is the end result



Here they are, staring and end pictures







I hope you have found this useful, if you have any comments please send me an email to: dergrunepunkt@gmai.com