Straighten and crop with Gimp
How to straighten (rotate) and crop a photo using Gimp.
One of the classic faults of a photo is a crooked horizon or a wide frame. Is really important to learn how to straighten and crop a photo to correct the errors done in shooting. Above you can see a wrong photo (left one). The lion is crooked and in the bottom-right there is a roof that must be removed.
Gimp allows us to straighten the image and fix this little errors of framing with very good results. I divided the tutorial into two parts, the first one is abouth straight and crop with Gimp, the second is about the rule of the thirds.
Straighten a photo with Gimp:
It could happen to return from a holiday at the sea, and discover that the photos of your friends, taken at the kiosk, has a completely awry horizon (maybe too many beers..), so you need to fix it. The Rotate tool of Gimp is the best solution
Select the Rotate tool from the
Gimp toolbox, then click on the photograph, a window "Rotate" will
appear. You should change only the angle value. It is not necessary to
change the center of the rotation. The angle parameter may be modified
with positive or negative values??. If you increase it, the rotation
will be clockwise, if you reduce the rotation will be anti-clockwise.
Adjust the angle until the image is straight, than click Rotate. Gimp can be very slow with rotation of high resolution images.
Crop an image with Gimp:
After straightening the image, there will be a gray chessboard on the corners. Obviously, Gimp is not able to invent the portion of the image outside the frame, so you need to do a little crop to remove it. in this tutorial I will exaggerate the crop. In the lower right part of the photo there is a chimney that i want to delete, the red line encloses the area that will remain after the crop.
Open Image - Canvas Size and reduce the height and length until you get a good result (look at the preview box).
The little chain on the right of the width and height parameters, is the "fix proportion". I suggest you to leave it enabled, so you will not change the aspect ratio.
If you want, you can move the image in the preview box for a rough positioning (hold left mouse button over preview image and move). Press Resize when satisfied.
If you are not satisfied you can still move the photo using the Move Tool in the toolbox of Gimp.
Is really easy, just select the Move Tool, then click and hold left mouse button on the image, and drag in the correct position.
Obviously, a good photograph should be shooted straight and well balanced in origin, but many times this is not possible (for example if you are shooting a fast moving object). Be careful, do not crop too much, or you will lose too many megapixels.
The rule of thirds:
Since I'm talking about crop and straighten, is a good idea to write something about the rule of thirds.
The most important thing to know about the rule of thirds is that the subject should never occupy the central position of the frame.
Place the subject in the center of the photograph gives a static and boring result, every image in fact has four points of interest (1, 2, 3 and 4 in the picture below), the subject should be placed in one of that.
In panoramic photos the horizon must pass through one of the two thirds (In the photo above, I choosed the lower one).
If the interesting part of the photo is the sky, you should leave 2/3 of the frame to it, if the sky is not very interesting, the 2/3 of the photo must be occupied by the ground.
There is only one exception: the reflections. If the photo depict a lake with reflections, is a good idea to leave the horizont in the middle.
The vertical shoots follows the same rule; The horizon must be placed in one of the two thirds, and the subject (for example a person, or a tree) should occupy one of the two vertical thirds line.
Is a good idea to leave more space in the direction in which the subject is looking, and place the eyes in one of the four points of interest, as you can see below.
Remember, rule of the thirds is one of the most important things to know for shoot great Photos.