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04-14-2010, 08:38 PM   #16
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QuoteOriginally posted by Wheatfield Quote
How do you figure that?
I was wondering that myself. Properly done PP improves image quality.

04-15-2010, 12:16 AM   #17
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QuoteOriginally posted by flippedgazelle Quote
I was wondering that myself. Properly done PP improves image quality.
He may be talking about reprocessing a JPG, which with multiple edit/save generations, Can and does degrade quality. With 12 and 15Mp sensors though, I think you have to go a long way for that to happen.

Re PF/CA: I've said it before, I'll say it again. I can make every single lens I own, Purple Fringe (in the generic sense), Including my Limited lenses. With some it's easier that others. We all know and love (or hate) the Tamron 70-300 that is especially well known for this..

Taken at 300mm f5.6 (wide open) K7



The photo is actually pretty sharp, not perfect but passable. PF, seems to really pronounce itself in the fuzzy edges in a slightly out of focus photo, such as the one above (click it for the peeper version).

I work in CS4 so the solution may be different for others but basically what I do, is fix the color balance, adjust the exposure, fill, contrast, etc until most of the PF is gone. All the while, trying to leave the photo looking natural. I often find that the PF tool in ACR while correcting Purple or blue fringe, will introduce red or green or some combo. So the sliders for that adjustment are set just at the point where one type almost disappears, and the other type starts. Then I'll play around with the Hue/Sat/Luminance sliders for each color to minimize the fringing. Have to be careful though not to destroy the colors of the photo that belong there. The same photo after a trip through ACR. Go ahead, click to peep....




Still not quite perfect but certainly much better. There is a bit of a trade off in this case. Some loss of color around the tree buds, where most of the real fringing was. For a shot of a couple black birds at the top of a tree, still a workable photo. Or at least I think so...

04-16-2010, 07:49 AM   #18
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QuoteOriginally posted by JeffJS Quote
He may be talking about reprocessing a JPG, which with multiple edit/save generations, Can and does degrade quality. With 12 and 15Mp sensors though, I think you have to go a long way for that to happen.
If so, it's a non starter. Jpegs can be saved as Tiffs, or PSDs or anything else once they've been opened, so there is no reason to save them in a lossy format if they are going to be resaved several times.
04-16-2010, 09:24 AM   #19
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QuoteOriginally posted by rawr Quote
With the K-x, of course, purple fringing/chromatic aberration can be removed automatically in-camera, if you are using a supported Pentax lens and saving as JPG. Can't get much easier than that.

Aside from that, most image editors, including Pentax DCU, will let you remove it or minimise it pretty easily.
QuoteOriginally posted by NecroticSoldier Quote
Oh, I have seen this function on the K-X but never really bothered with it or read into it. Thanks, but I might be using a Tamron 70-300mm that has SOME PF... ;/
QuoteOriginally posted by rawr Quote
I recently picked up a Tamron 70-300. It's not as good as it could be re PF, but it ain't too bad at all.

What graphics software do you normally use?
be careful, lens correction in body is opnly for pentax lenses
QuoteOriginally posted by shawnxji Quote
I know that in Paint Shop Pro, which is what I use, there's the Purple Fringe Fix to remove purple fringing. Depends on the colors in your photo it might or might not work perfectly.
I use PSP X3 and while there is a purple fringe tool i found it to be very poor, BUT the CA correction tool is excellent. Forget all about using the PF tool, the CA removal tool is so much better at not just purple fringing, but also for different colors of CA, including lateral CA (purple on one side green on the other) because it can manage multiple color ranges in one function, and yo can control not only the range of colors but also the pixel radius for correction

04-16-2010, 10:15 AM   #20
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I rarely get PF with any lens, myself. One can partly chalk this up to the fact that most of where people complain about it will be tree-branches against a bright sky, ...which is a kind of subject I'll tend to only squint at rather than try and photograph. It seems to me that my habits of exposure make PF pretty much a non-issue. Old film habits of just letting the sky go, most of the time, I think, are part of it.

My attitude's usually more like, "If this'll agree with my scene,maybe if I put a polarizer or contrast filter on, great." But I just expose for my subject and rarely seem to run afoul of PF. Sometimes it'll pop up when I've put a camera on automatic precisely cause I can't see so well. If it weren't getting hard to do at this point, I'd say, "Shoot some Kodachrome and get it out of your system."


I still sometimes get this feeling that where people say, "Expose to the right, my camera is therefore superior at higher ISO to yours... (cause I overexpose anyway) " ...may be an artifact of how people figure things 'ought to look,' when in fact, maybe that's more about where the tech competition is, (dynamic range) ...and not where the best image is. Your mileage may well vary, but maybe see about your exposure before worrying about the lens.
04-16-2010, 10:36 AM   #21
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QuoteOriginally posted by Ratmagiclady Quote


I still sometimes get this feeling that where people say, "Expose to the right, my camera is therefore superior at higher ISO to yours... (cause I overexpose anyway) " ...may be an artifact of how people figure things 'ought to look,' when in fact, maybe that's more about where the tech competition is, (dynamic range) ...and not where the best image is. Your mileage may well vary, but maybe see about your exposure before worrying about the lens.
If I'm running full manual (M mode), I'll go to the left of center most times. Expose for the shadows, process for the highlights. Sometimes it becomes a balancing act between shadow noise and fringing (in the generic sense). I've found that, if I'm looking for detail in all areas, underexposing a little is the way to go. Don't like those blown highlights, and yes, it will reduce the fringing quite a bit.

04-16-2010, 10:53 AM   #22
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QuoteOriginally posted by JeffJS Quote
If I'm running full manual (M mode), I'll go to the left of center most times. Expose for the shadows, process for the highlights. Sometimes it becomes a balancing act between shadow noise and fringing (in the generic sense). I've found that, if I'm looking for detail in all areas, underexposing a little is the way to go. Don't like those blown highlights, and yes, it will reduce the fringing quite a bit.

Hee. That does seem to sum up most of my own experience, particularly when I look at histograms. When I finally start getting hardcopies back, we'll see how well that works in the final product, but there we are.

I don't generally care about 'blown highlights' in the background, ...frankly, that's how the world looks to me. (Again, I have this sun-sensitivity thing going on: what many call a bright day actually *looks* rather like Ektachrome two stops over to me. ) I suspect that HDR would tend to look rather unnatural in my case, though there are times when it'd let me do things I'd always wanted to that would have taken more masks and things in the darkroom than they'd have been worth. As a rule, though, it's like, 'If the sky ain't cooperating, let it go.' Where you don't want blown highlights or (blocked-up ones, in terms of negs) is on your *subject.*
04-16-2010, 11:17 AM   #23
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QuoteOriginally posted by JeffJS Quote
I work in CS4 so the solution may be different for others but basically what I do, is fix the color balance, adjust the exposure, fill, contrast, etc until most of the PF is gone.
I really like the purple fringe PS action the author of PTLens has available. It can remove any color fringe, not just purple. You color pick the fringe on the photo as the first step, picking the color and setting a range around the color for inclusion or exclusion, then the script identifies where the color occurs around the edges in the photo, and turns the range into a gray scale. Multiple passes will remove more of the color if the first pass wasn't enough.

I don't know of a way to directly link to the PF tool so just follow the link above and then on the left hand side, follow the Downloads link, and then follow the Purple Fringe link.

Thank you
Russell

04-16-2010, 12:23 PM   #24
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I use a photo software called adobe lightroom and it has a very easy way of removing chromatic abberration. All you do is slide sliders back and forth and watch what they do to the picture. The newest version is due to come out very soon so I would look at that as I highly recommend it.
04-16-2010, 12:43 PM   #25
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QuoteOriginally posted by Tuner571 Quote
I use a photo software called adobe lightroom and it has a very easy way of removing chromatic abberration. All you do is slide sliders back and forth and watch what they do to the picture. The newest version is due to come out very soon so I would look at that as I highly recommend it.
ACR in CS4 works the same way but it won't get rid of all of it on it's own. I had posted this to another thread but I can't find it right now (may have even been this thread)..

The ACR portion... There was no HSL manipulation for this particular photo.










The CS4 Portion (Curves layer mask to bring back the blown out sky)..



The final image



04-16-2010, 01:27 PM   #26
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QuoteOriginally posted by Wheatfield Quote
How do you figure that?
Using a lossy format, as Jeff stated:

QuoteOriginally posted by JeffJS Quote
He may be talking about reprocessing a JPG, which with multiple edit/save generations, Can and does degrade quality.
QuoteOriginally posted by Wheatfield Quote
If so, it's a non starter. Jpegs can be saved as Tiffs, or PSDs or anything else once they've been opened, so there is no reason to save them in a lossy format if they are going to be resaved several times.
If someone is asking if removing purple fringing is hard what is the likelihood they know the difference between a lossless and lossy format?
04-16-2010, 11:07 PM   #27
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QuoteOriginally posted by noahpurdy Quote
Using a lossy format, as Jeff stated:





If someone is asking if removing purple fringing is hard what is the likelihood they know the difference between a lossless and lossy format?
What's the guarantee that they don't? I have no idea if removing PF is easy or not, I've never bothered to try doing it with more than the sliders in camera raw.
It's all part of the education process.
The OP now knows not to resave as jpeg if he intends to work a file over several sessions.
And so do you.
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