NB: If you have problems viewing images in this tutorial:
Right click on the white square with a red and click on the "image display".
Select the Ruler tool (shared with the eyedropper tool)
Draw a line from left to right of the photo at the horizon line to straighten.
Click Image / Image rotation/ Arbitrary
Let the value already present (it is the value that was measured by the rule tool), simply click "OK"
The image is now rectified. We must crop the image.
To crop the image, we will use the crop tool because it has the advantage of preserving the aspect ratio of the original photo.
To enlarge or shrink the frame, click on the banks of the frame.
To move the frame, click on the center of the frame.
To apply the new frame, press the Enter key on your keyboard (ENTER)
Here is the result of our image rectified, cropped.
To eliminate blur on the picture, I sharpen the image.
The method to eliminate blur an image by the sharpen method is described in another tutorial.