Correcting Converging Verticals

Clive R. Haynes FRPS

When we photograph a scene and tilt the camera either upwards or downwards we inevitably introduce a distortion of perspective. This effect is often simply not noticed in a general landscape scene or in pictures of people, however when photographing buildings we become acutely aware of an exaggerated perspective caused by excessively converging verticals.

This problem is swiftly corrected in Photoshop.

Before correcting you may find it beneficial to add some extra 'canvas' to the image, do this via Image > Canvas Size > add around 20% more width & height. Ensure that the area showing is at the centre of the nine small rectangles in the Canvas Size dialogue box and click OK. This little, nine-square box tells Photoshop where to place your image on the canvas. This will now give some 'elbow room' to see what's going on.
It may be very helpful to use the 'Grid' feature in Photoshop to act as a reference.

To show the grid in Photoshop V6 / V7 go via Ctrl + Alt + @ or by View > Show > Grid

To show the grid in Photoshop 5 / 5.5 go via Ctrl + @ or by View > Show Grid

This is a 'toggle action' and by repeating the above the grid will be turned off.

'Select All' either by Ctrl + A or via Select > All
Next go to Edit > Transform > Perspective
Use the corner 'handles' to make the desired correction and press 'Enter' when OK.

The 'error' may not have been uniform, therefore, should additional correction be necessary, use 'Distort' or 'Skew' from the Transform menu. These allow independent correction at the sides of the image - be watchful as they do have slight effects upon adjacent/opposite sides of the picture.

Some cropping of the image will be necassary to trim the 'trapezium shape

Tip: Don't over correct. That is to say it's often preferable to leave a little convergence as this does give a sense of perspective. A dead vertical building, especially if viewed from a low viewpoint, tends to look very unnatural.
Related Topic
Correcting Sloping Pictures
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