Here's a typical glitch in a stitched image:

To correct this in Photohop, make a rough selection around one side like this:

Then cut and paste the selection (ctrl/c followed by ctrl/v). This gives you the selected area on a separate layer above the main image. Select Edit->Transform->Rotate

Drag the centre point over to the right hand edge of the selection. The idea is to rotate the selection about that point to bring the left hand edge into proper alignment, without producing a misalignment at the right hand edge. (The skew option can also be used instead of rotate).

So click and drag the selection around (zoom in with ctrl/+ to do this accurately). You might then need to erase edges of the patch layer so that they merge seamlessly into the layer underneath. The result looks like this after flattening the image into a single layer:

Any untidiness at the join now needs to be cleaned up with the clone tool:

Other options of the Transform tool will also be useful on occasion.  The Puppet Warp tool is another option too.

John Houghton
30 September 2013