Ugly purple banding! Help!

[MrJorge]

Ok I've just processed a few trial real estate shots I've taken for a mate. They're nothing flash and I have a lot to learn so let's park that for a minute and I'll start a thread in the appropriate area for general C&C.

What I'm after here is how to get rid of that ugly purple/pink banding around some of the edges. It looks to me like CA but none of the CA tools in CS5 or LR2 seem to be affecting it at all.

Anyone got any suggestions on how to remove it? It's really distracting and doesn't appear to be there in the originals (these are HDR).

http://farm5.static.flickr.com/4038/4665454043_050c5ca32c_b.jpg

http://farm5.static.flickr.com/4012/4666077750_bc96df2d6b_b.jpg

http://farm5.static.flickr.com/4044/4665454459_0567b8cd92_b.jpg

[stevemack]

Mate its definatley CA thats for sure,i reckon The HDR process has caused it.

steve.

[MrJorge]

Yeah I've just noticed that the CA tool is making a very minor indent into it.

Maybe I need to apply the CA adjustments to the originals (even though it's not noticeable) or something and do the HDR again. I'm not going to but interested in any suggestions anyone has.

[Cage]

Mr Jorge,

The purpose of these pics is to tell a story about a property. I think you've done that.

I doubt there are too many 'pixel pervs' looking in Real Estate Agents windows.

Cheers

Kevin

[arthurking83]

I'm inclined to look at it from trublu's perspective, in that they're not distracting enough to warrant any action.

But then again, there's also nothing wrong with learning new stuff too!

So!.. how about identifying and eliminating that colour with a colour channel thingydoodle minimisation.

Sorry I dunno a thing about using whatever program it is that you use, but in my program of choice I could run a paintbrush selection over the affected pink areas and slowly lower the saturation of that colour channel.
I remember trying that to a minimal degree of success with proper full blown CA affected images, where I reduced the magenta channel slightly enough to minimise it(but not eliminate it 100%).

I'm also inclied to think that the pick banding is not CA in the proper sense(and remember I don't do HDR) but what I do regularly see in HDR images is a strange colour cast in shadows)

CA is a colour fringing caused by the condition of having high contrast(ie black against white) etc. the pink banding in this images are not due to high contrast(because there are areas of more contrast that are not affected! As an example the dish rack in #3. Those chrome dish racks are generally considered to be a CA magnet when a direct light source is upon it!

How were the WB values set for each image? did you jsut keep them at Auto, did you set them in PP, or manual configure them at the time of the shoot.. etc,etc.

remember not having personally done a HDR in anger, I have no idea on the processes behind it.

[MrJorge]

Thanks for the thoughts of if they work as is (they look very dark here on my work monitor though... what do others think?). But as Arthur says there is no harm in trying to learn what went wrong and possibly how to rectify it.

Arthur, I'll give the colour selection and saturation decrease a burl. I use CS5 & LR2 so I'll just look into how to do that.

I agree with you though about how weird it is. It looks like classic CA but yet there is enough weirdness about it to make me wonder if it isn't. As I said it's not visible in the original exposures prior to HDR'ing but perhaps it got amplified as part of the HDR process. Or it is an artifact of the HDR process somehow.

WB was Auto. Which gives me an idea for the interior ones. On a few interior ones I shot (not shown here) I remember fixing the WB to Tungsten prior to HDRing. I'm not sure I did on these ones. Perhaps that is behind it to a degree, will try again with Tungsten WB versions of the original exposures.

The exterior one the WB was Auto. Pretty sure I didn't adjust prior to HDR. Not really sure the WB was out though. Whites look pretty white to me.

Thanks for your thoughts. You've given me a bit to think about.

Trying to nail the issues with these as an opportunity is presenting itself to do a bit of paid real estate work. Nothing major but it could give me some pocket change for new gear etc.

[arthurking83]

Hey again Michael.

I have to say LR is hard for me to understand, but slowly I'm getting more used to it, so here goes:

I had a play with it in LR3_Beta2, so I can explain what steps I did, coz my explanations in using Capture would be gobbledygook to you :D(ie. I hope LR3 works the same as LR2)

I adjusted WB to +15 to start with and the purple instantly disappeared with no other adjustments, but made the image look way too yellowy.
Then I played with saturation in various channels. Once I figured out where that tool set was and how to work it, it became clearer and easier. I inadvertently started playing with hue, not realising .. how to work this program.

53329
here's the adjusted image now, and I think if you set WB correctly in the pre stacked images it may not need playing with once stacked into a HDR(but I don't know this.. just a guess)

I adjusted a few channels as follows(more to see how this all works, than anything else!)

Orange- Saturation -20, Luminance -10(luminance was more for seeing how it all worked rather than a necessary step, so you'd adjust them as you see fit to adjust them)
Yellow- Sat -100
Magenta Sat -60

Note just the simple adjustment of the magenta channel helped by itself (down to -100), but as I said I was more curious about how the program worked and suchlike as well as getting to the bottom of the problem. Which I think is a WB issue.

So the two main PP edits that helped with getting the magenta highlights out of that particular image were either WB +15 or magenta Saturation -100, and combinations of others also helped.

So you could probably do more and better with your files for sure.

hope that helps a little.

[MrJorge]

Arthur, many thanks for the effort you put in.

I just tried adjusting the WB prior to the HDR process. Immediately seemed a bit better, but still visible (to my eyes).

I adjusted the WB Temperature by +5 (not quite as high as you as I too didn't like the yellow cast introduced) and it disappeared even more.

I also had a play with the Magenta saturation but it had zero effect. In my new file it was the Purple channel that was at work. So I dragged it to -100 and it looks much, much better.

Interesting I tried the targeted adjustment tool for the colour saturation adjustment. Basically you click the icon then click on the colour in question in the photo and simply drag the mouse down for desat and up for saturation boost. Even though I zoomed right in and was very careful to select the purple banding the desat was messing with other colour channels and not the purple. Weirdness.

Here is my newer version.

http://farm5.static.flickr.com/4005/4669038594_00225ec2ed_b.jpg

Thanks again Arthur, you're a good man. Opened my eyes to a few things.

[wideangle]

Try going to your saturation menu and just selecting the magenta (i think it is) from the list and desaturate

[arthurking83]

yeah that looks better and the WB looks more as you'd expect it too.

[ozwebfx]

G'day!

Were the HDR images derived from a bracketed set or a single image forced to different exposures?

[Ray Heath]

Um, I don't see any banding, in fact I don't see much "wrong" at all.

What is CA?

Ray

[OzzieTraveller]

G'day Michael

Just to put it into perspective ..
-- putting on my hat as a potential property purchaser ~ I have just spent a week looking at a dozen or more properties to purchase (and ended up making offers on two)
1- your camera work is excellent
2- my laptop does not show the "problem" as much as you can see it and are worried about it
3- the images of the property DO show me all that I need to see prior to contacting the agent for further viewing

So - photography wise, you have done an excellent & very professional job

The latter images where you have lightened [via WB or exposure doesn't matter] are better from the potential purchaser's point of view

Regards, Phil

[MrJorge]

G'day!

Were the HDR images derived from a bracketed set or a single image forced to different exposures?

All of them were from bracketed exposures.

I did do some from a single exposure pushed to different exposures in LR, but these 3 examples were all bracketed on camera.


Um, I don't see any banding, in fact I don't see much "wrong" at all.

What is CA?

Ray

This might explain it better than I can.

http://en.wikipedia.org/wiki/Chromatic_aberration


So - photography wise, you have done an excellent & very professional job

The latter images where you have lightened [via WB or exposure doesn't matter] are better from the potential purchaser's point of view

Regards, Phil

Thank you for your thoughts Phil.