Chris Maddock's Tutorials & Articles


Correcting Horizons, by Chris Maddock

Whilst one can use the Measure Tool to straighten horizons, a quicker method that I prefer is using the Crop Tool. The advantage to this is that it saves having to crop after rotating your image and you can set it to retain the aspect ratio of the image - usually I also use it to retain the overall image dimensions by having it enlarge the cropped area slightly.

Firstly locate the Crop Tool. In PS7 it's third from the top in the lefthand column of the toolbox. In its basic mode it allows you to draw a rectangular selection over an image and crop to that selection. However, as well as that it allows you to rotate the selection and even resample the selection to a given size.

Once the Crop Tool is active, we need to set the options for it in the toolbar as shown below.

I prefer (unless the skew is very bad) to have the straightened image resized to the original size so I have entered the Width, Height and Resolution values of the original. If you leave them all blank the tool will simply crop the image without resizing - it will also not be constrained to an aspect ratio.

Having set the tool options, I now draw a selection over most of the image, as below;

Now I drag the selection so that one of the long edges is close to the horizon that I want to straighten;

This done, I now move the cursor near to one of the selection corners and it becomes a rotation handle - clicking and dragging rotates the selection as opposed to moving it. I rotate the selection so that the bottom edge is parallel to the horizon that I want level.....
..... before dragging the rotated selection back across the image.
Finally I adjust the size of the selection by dragging the corner handles in or out until the selection is completely contained within the image area;

Once I'm happy with the selection angle and size, I'm ready to commit to it.

Either a double-click within the selection area or clicking on the Tick button in the tool bar will make the changes;

There we are, a nice, level horizon - very reassuring for the residents of the Isle of Wight downstream ;-)


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All text and photos are copyright © Chris Maddock, 2007