Hello, and welcome to this, the final part of my tutorial series on doing photoediting with GNU/Linux and free software. I say final because after this, we’re getting into the professional arena for which good books are a much better option than blogposts. What I will be covering in this is some basic photographic handling skills and how to do them in the gimp. I won’t be using channels or layers in this tutorial but everything in here remains applicacable when you use them.
A common problem for a photographer when you shoot outside a studio, is that your light and color and backgrounds are not ideal, so we’ll learn how to do some basic corrections, and how to highlight our subject against a cluttered background. Here is a picture I took at the 7thson gig, it was near the end of the show and to get it, I had to use a very high ISO level as the light was fading and I wasn’t using a flash. The price I paid was digital noise – and the background is rather cluttered.
Here you see the image, in UFRaw, with our first bit of highlighting already busy: we’re cropping out some of the wasted stuff.
I’ve not done much else in RAW on this one as the shot was really rather good, I only raised the exposure level very slightly.
Clicking on OK gives us the image in GIMP:
Our first problem is the digital noise that came from using a high ISO level, Gimp has a built-in tool to help correct this, called Despeckle (Filters|Enhance|Despeckle). UFraw also has such a tool but it offers far less control, despeckling costs you detail so you want to aim for an optimum balance to lose as little as possible and maintain a usable picture (if perhaps not a print-quality one).
This gives us a much better picture already. Now we can reduce some of the effects of despeckling by going for a softer-focussed image, for this we use one of GIMP’s most useful tools, the Gausian Blur, with a smallish radius, it just softens the focus enough to smooth out the picture without losing so much detail as to harm it – in fact, it makes it prettier.
Now we want to deal with the background, ripping it out is possible but will cost us all context, instead we just want to remove it’s eye-pulling effect while maintaining it’s presence, so it provides atmosphere rather than interference. I started by removing the drummer’s half visible head (as it contributed nothing) using the clone tool (I cover this in detail below), now for the fun part though – selecting the background outside the guitarist. Gimp offers an easy way to select complex shapes using the Path tool by clicking along the contours you can gradually select out your target.
Now we use Select|From Path to turn our path into a selection. You can also use the lasso tool for this, but only if you have a very steady hand. We will begin by reducing the coloring of the background making it effectively a semi-black-and-white image, thus reducing it’s distracting effect a great deal and making it nice for atmosphere. First we need to adjust our selection a little, we start by shrinking it until it is just inside the border of the guitarist (Select|Shrink Selection) – so we’ll have a smooth transition, then to smooth things further, we feather it (Select Feather) by about 5 pixels.
We invert the selection to select the background around the guitarist rather than the guitarist himself, we open the Hue/Saturation tool from the colors menu. and drop the saturation a good deal – this gradually reduces the coloring of the background, until we get a near black-and-white effect with just enough color to still look nice.
Below, you can see the results, already an improvement, but there’s a catch – look at the guitar cable, it’s now much brighter on the player’s leg, and thus causes a problem, luckilly the way it runs, if we remove it, it will just appear that it ran behind him – so we have an easy answer, just get rid of it.
For this we use gimp’s clone tool. Cloning lets us take one part of the image and paint over another with it, it’s a powerful tool but at it’s most basic, using a feather-edged brush of about 35-pixel diameter and the aligned mode, it lets us quickly paint out the cable using the surrounding denim.
Now all we do is another small gausian blur to remove the edges from the changes we made, and here we have our final result, it’s pretty, it’s got atmosphere and we’ve turned a bad-luck shot into a work of art.