Pano tools chromatic correction for Pentax 6x7 45mm...

Correcting Pentax 6x7 lenses is specialized territory. However, my
tutorial on using Panorama Tools for this purpose may be of some use:
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Of course, scanned film images will respond as well to this technique
as will direct digital images. Regardless of what people may say, you
*can* improve this aspect of image quality (along with distortion)
even after the image is on film.

Brian
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On 19 Nov 2004 17:01:46 -0800, (ChasFS) wrote:

While I don't have CA problems on my P645 lenses, I sometimes have
them with my 35mm setup.
I gave up trying Panotools (too difficult to achieve a proper R/G and
Y/B parameters set), but I found "Debarrelizer", a shareware plugin
from The Imaging Factory, very useful. It has sliders for CA
compensation. Quite effective with the typical R/G and Y/B color
fringing. Can do nothing for scanner-induced purple-fringing and other
CA-related artifacts, but it's quite better than nothing. :-)
By the way, it can do defishing as well (as the name implies).

Fernando

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In color imaging, CA in the lens results in color fringes, red to one
side/blue to the other, at high-contrast edges in the corners of images. The
worst visual aspects of this can be cleaned up quite nicely, resulting in
images that are quite usable where there had been disturbing color artifacts
before.

It's a useful, well-known technique for direct digital capture. I'd think it
would be a bit harder to take advantage of in scanned MF, but it's worth
looking into if you have that problem in your images.

David J. Littleboy
Tokyo, Japan

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Do you know what chromatic abberation is? It's in the camera & lens. You
aren't going to recapitulate detail that is not on the image plane. I
suggest you find what it is about your images that is bugging you and fix it
in the camera (learn how to take a picture), and if you cannot, then move
on - or dither yourself to death with digital nonsense.