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Perspective control in Paint Shop Pro8.0
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| Paint Shop Pro8 has some of the
most elegant and easy to use distortion/perspective control tools in existence.
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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.
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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.
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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.
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The scene with Barrel Distortion
eliminated. |
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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.
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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.
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| 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. |
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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.
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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.
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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.
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©2004 Larry N. Bolch
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