How to straighten a picture

Let's say that you were in a hurry, and took a picture that is actually a little bit twisted. Just like this one


To correct it, you need to find the Ruler Tool (under the Eyedropper Tool), then you need to draw a "line" joining 2 points that are supposed to be inline if the image was straight. Follow the example below and start making the first click somewhere in the red selection, and the second and final one in the next red selection.


Now, go to Image - Image Rotation - Arbitrary (notice that a value is already inserted there) and hit OK. Photoshop will straighten up the image, but notice now that we must get rid of that white border. The solution is to crop the image, using the Crop Tool.


Make a selection, and then rightclick on it and select Crop.


The final image should look like this