GIMP Tutorial - Simple Photo Editing for the Complete Idiot
How to Get Started Using Gimp—a Free, Opensource, and Powerful Photo Editing Program
Perhaps you've heard what a great, free photo editing program GIMP is. If you haven't, let me clue you in. GIMP's toolbox rivals Photoshop's, and it is truly quite similar in function. If you want to move beyond that cheesy software that came with your camera, but you're not ready to spend the money for Photoshop, GIMP is a good next step.
If you've taken the plunge and downloaded and installed the software on your system, and you have absolutely no idea what to do with it now, you've come to the right place. We're going to take it slow and easy, and start at the beginning.
For this tutorial, I'm using GIMP 2.6. That's important, because the menus change with each new version and features are added removed or modified.
Save a Copy of Your Photos First
Before you start, it's a good idea to make a copy of your photos, just in case something goes horribly wrong. If you have several photos you want to edit, the easiest way is, put them in a folder together, then make a copy of that folder. Make sure to name it something easily distinguishable from the original folder.
Open Your Photo in GIMP
Now, just open your working folder and right-click on the photo you want to edit, on the menu that pops up, select "Edit with Gimp," and your photo opens. I've noticed that if I have another window open on my desktop sometimes Gimp will open behind that window, so if you don't see your photo pop up, try minimizing any other windows you have open.
Cropping a Photo in GIMP
If you want to crop your photo, you can do a simple crop by clicking on the rectangle tool at the top, left of the toolbox, then dragging to draw a rectangle around the area you want to keep. If you want the cropped image to be a perfect square, you can hold down the shift key while dragging. Once the selection is made, go to "Image > Crop to Selection."
Using the Crop Tool in GIMP
If you need to have more control over what size your cropped photo is, you can use the cropping tool. That's the tool that looks like an X-acto knife. If you click it you get some boxes at the bottom of the toolbox you can fill in to choose how you want to crop, leave those as they are for now.
Drag to draw the rectangle for your crop, just as you did before. Then go to the bottom of the toolbox. To crop by size, just type in the measurements you want your finished photo to be.
The default measurement unit is in pixels, so if you want inches or some other unit of measure be sure to change it. After you put numbers in the boxes it may change the aspect ratio of the box (change the width or height).
You can make adjustments to the numbers or move the box around if you need to. When you have the box where you want it, then hit enter and your rectangle will change to the designated size. When you have the rectangle positioned the way you want it, click inside of it and your photo will be cropped.
Color Corrections and Light Adjustments
In the menu at the top of the new window, look at the options under "Colors." I like to start with "Curves." So, select "Curves," and you'll see a diagonal line on a graph. If you use your mouse to pull on the end of the line at the bottom, left of the graph, it will adjust the darkness of the darkest part of your photo, making it darker or lighter. The top, right end of the line has a similar effect on the lightest part of the picture. You can pull the center of the line up or down, creating a curve, to adjust the mid-tones. Make sure that the preview box is checked so you can see how you are changing your photo while you work.
Try the other options under "Colors," like "Color Balance" and "Brightness-Contrast." Do some experimenting with those tools to see what they do. Each time you get some changes made that you're sure you want to keep, save your photo, then if you mess up you can always go back to that last saved version.
When you get everything the way you want it, click OK. If the picture gets all messed up, no worries, just click cancel to close the curves message window and start over.
Any time you mess up in Gimp you can hold down the Ctrl key and hit z that will undo your last action. Gimp allows you to undo many steps.
Brighten it up With Unsharp Mask
Another favorite tool of mine, that is a super easy way to enhance a photo, is unsharp mask. It's under "Filters > Enhance > Unsharp Mask," all the way at the bottom of the menu.
There are three different sliders you can adjust while you're previewing your image. You'll just want to move them a little at a time, too much and the image will look fake. The effect should be subtle, but it can really add sparkle.
Gimp will save the photo in the same format it was in when you opened it, for instance a jpeg will automatically be saved as a jpeg. If you want the photo saved in a different format than it was before, do a Save As... and either change the extension in the name (the letters that come after the period, such as .jpeg or .tiff) or select a file type by clicking on the + button next to "select file type" in the message window and choosing from the list.