Perspective control in Paint Shop Pro8.0

Paint Shop Pro8 has some of the most elegant and easy to use distortion/perspective control tools in existence.

There are tools for both lens distortion and for perspective distortion.

Since the interface is customizable for the user, locations may vary from those shown.

The example we will use in this case is an extreme wide angle shot with the 19mm equivalent WC-E68 lens component on a Nikon CP5000, of downtown Edmonton, Alberta Canada.

Since the lens was tilted up, it has produced a shot with profound keystoning. Like most wide-angles on zooms, there is a bit of barrel distortion as well, though remarkably little for a lens such as this.

First, we deal with lens distortion, which may be either barrel or pincushion distortion. To identify which you are dealing with, samples can be viewed here.

The Barrel Distortion tool is entirely interactive and one can have it proof on the working image in order to judge the effect, as well as comparing the results close up in the preview windows.

Settings can be saved as Presets and reused.

There are also tools for Fisheye and Pincushion Distortion that work in exactly the same manner.

The scene with Barrel Distortion eliminated.

The Straighten Tool is a line with a handle at each end. If the image is somewhat rotated, choose either a horizontal or vertical line and pull the Straighten Tool along it. Clicking on the OK checkmark on the Tools Options Palette will make it take effect.

As the tool does its job, the canvas increases in size to accommodate the rotation. PSP8 gives you the option of having it crop the excess automatically, maintaining as much of the image as possible. See screen shot at the top, where this feature is circled.

While this tool is extremely useful as shown here, it is also very useful for correcting scans when the original is difficult to line up. This is specially important for scans intended for optical character recognition (OCR) of text or music.

Drag the lines of the Distortion Correction Tool along the lines of the buildings you want to correct. Click the OK checkmark and they will line up vertically or horizontally.

Again, you can choose to let the program do the cropping or let you do so.

All verticals are now actually vertical. All that remains is to do a final cropping. The cropping tool is located just below the distortion tools in the tool palette.

Drag the Cropping Tool over the area you want left in the image. Once drawn out, it can be carefully adjusted by tugging on its handles.

Click the OK check-mark to perform the crop.

The final result is a completely corrected image. Perhaps too much a completely corrected image since there is an effect of the buildings flaring outward to the top, since our eyes expect a bit of perspective.

Thus the process does depend on the good taste of the person doing the processing, to create a believable, acceptable image. Above all, trust your eyes - correct is not always right in photography. Photography remains art rather than science, no matter how advanced the technology of the tools.

I had an occasion to use these tools for an interesting application recently.

The room at the left is in a historic house at Calgary's Heritage Park. A dear friend who does beadwork, was deeply impressed by the large beadwork picture on the wall and asked that I photograph it for her.

The room was roped off, so I shot at the best angle that was available. It was a busy day at the park and I did not want to spend the time tracking down a curator to get permission to enter the room.

The Perspective Correction Tool was able to produce the equivalent of a shot where the camera was perfectly square to the picture! See inset at bottom of image.

©2004 Larry N. Bolch