Software to Remove/Repair CA in PP?

*monochrome* · 09-08-2009, 06:39 PM

Just got a Tamron Adaptall-2 SP 70-210 #19AH. Went out to play over the weekend and for the most part this lens rivals my Vivitar S1 70-210. There is some pronounced purple CA, though, in the high contrast areas of this shot - a fault I hadn't read about in this lens.

Is there a freeware or a utility in say GIMP/ACDSee/IrfanView that can clean this up? Or is there better technique (better DoF planning, etc.)?

I thought I read a discussion here about a year ago but I can't find the thread.

100% Crop K10D 1/125 f/13 Manual ISO 100 Multi-Segment Metering +/-O EV bias Polariser

Images are unprocessed.except resize

*MacGirl* · 09-08-2009, 06:59 PM

Looks like you were at the Botantical Gardens.

I try to avoid those situations with my 70-300 but if I do get some PF I usually diminish its appearance in Photoshop. Sounds like you don't have PS though. I go into the Hue/Saturation menu and adjust the magenta and blue levels until I'm happy. Maybe there is a menu something like that in Gimp, I'm not familiar with it.

with those adjustments....

*monochrome* · 09-08-2009, 07:07 PM

Hi MacGirl: Thanks for your reply.

As I posted this I though of Magenta saturation - I have Elements. Wondering what that would do to the color in the balance of the image. I'm guessing there is a way to make a new layer and remove the fringe from it, then merge them again. I'm hoping some piece of freeware does that kind of operation (or some other one) in one step.

I took this (and a few others) in Kirkwood Park, a very heavily used city park. There is just this one small section that is kind of woodsy overlooking the small lake / large pond.

It is reminiscent of some views of the Japanese Garden at Shaw's, now that you bring it up.

*MacGirl* · 09-08-2009, 07:15 PM

Just play around with it. But only change the blue and magenta channels in the Saturation and Lightness areas of the image. I've not noticed these adjustments making a noticable difference in the overall color balance of images I've had to use this technique on and I've not had to use layers.

full image fixed PF:

*monochrome* · 09-08-2009, 07:20 PM

Very nice - thank you. Now I just have to straighten, sharpen and mess with light.

Fortunately I took several and this wasn/t the best. It ism the one with the most noticeable CA.

kenyee · 09-09-2009, 09:13 AM

search for "gimp purple fringe plugin" in google. I've used Darla's script successfully w/ my Tamron 70-300 which is sharper than Sigma's but has PF...

*monochrome* · 09-09-2009, 09:59 AM

Originally Posted by kenyee

search for "gimp purple fringe plugin" in google. I've used Darla's script successfully w/ my Tamron 70-300 which is sharper than Sigma's but has PF...

Thanks - (plus required characters)