What is this Fringe and can it be avoided/fixed

[ScoutR]

Good Morning Everyone:

Could someone tell me what the bluish fringe outline is along the front of the cat, and how I can avoid it in the future for this type of shot and in this case if and how it might be fixed.
All I have done so far is add a bit of fill light. The cat was very dark because of the backlighting, and I'm thinking I should have upped the exposure a stop, but if I had done that, I think the fringe would have been even worse as the background would have been even more overexposed. As usual, all help is appreciated.

[Colin Southern]

Hi Scout,

The short answer is it's caused by the strong back lighting - best way around it is to expose the background properly and then get a proper foreground exposure by using flash.

[arith]

Yes I can agree with that; it is a chromatic aberration caused by strong contrast. Nice pussy cat and pic though.

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

[ScoutR]

Thanks Colin and Arith

The subject won't allow flash (it's in his contract) so that's out.

Thanks for the link Arith. Very interesting. There's a link at the bottom on how to correct this problem. I don't have the same software specified in the instructions, but translating it to Lightroom, I was able to tone down the blue fringe a bit and it's not quite so obious now.
It also suggested that in some cases using a smaller aperature I might be able to avoid this chromatic abberation (new term to add to my list) If the model decides to pose in the window again I will try that and see if it helps.
I'll also try exposing for the highlights and then brightening up the cat instead of vica versa which doesn't work at all.

Thanks again

[arith]

That's good; you cheered me up no end Wendy. I hope you can make your fantastic vision in this photo work; because I like it. Steve

[proseak]

I do have a partial workaround for this, using LAB colour in Phototshop. Here's how;

Image > mode > Lab colour
magic wand, tolerance 30-50, check boxes unchecked
Select > "the light bits, often the sky" Modify > Expand 20 pxls
Feather 15 pxls
Channel 2 > Filter > Gaussian blur 7-25
Channel 3 > Filter > Gaussian blur 7-25

Image > mode > RGB

Where "Channel 2" is a, magenta/green and "Channel 3" is b, blue/yellow

This reduces the colour variations, and reduces the coloured fringes to grey. The numbers that i've used are just a guide; you may find that others work better for you. I'm uploading my "take" on your pic, and would like to hear your comments

HTH

proseak

Looks like the pic's gone missing - here's the url - hope it works;

[ScoutR]

This reduces the colour variations, and reduces the coloured fringes to grey. The numbers that i've used are just a guide; you may find that others work better for you. I'm uploading my "take" on your pic, and would like to hear your comments

Thanks Peter: Your version looks very good and has reduced the fringe to an acceptable level.
I have copied this info into an evergowing document with tips from the forum. I will try to translate this into Elements and have a go at it. I'm trying to avoid the fringing in the first place, and it's getting better, but with backlighting I still have problems.

Thanks again, very helpful
Wendy
Edit: By the way, stay tuned, it might be awhile till I can get at it, but when I do, I might need some help

[David]

Wendy - I've just been having a chat with Tom, one of my Maine Coons. He doesn't believe a word of what you're being told about colour fringing. He points out, quite vocally, that what you are seeing is the cat's natural aura. Tom is of the view that if your cat finds out that you've captured his aura in a photograph, there may be pussy hell to pay! No more snaps at all, let alone flash. So, Tom thinks you should keep mum, chromatic aberration indeed!

Cheers

David (& Tom)

[proseak]

"I will try to translate this into Elements and have a go at it." - Difficult, that - PSE doesn't yet support Lab colour so I'm having a look at the GIMP, to see how easy it is there.

More later...

Peter

[willgoss]

I also would try to improve the situation...

I would treat the problem area as Haze.....select the area, add feathering, and run Unsharp Mask at a high Radius perhaps 50 then with curves touch up the selected area.......

You could also have run the USM over the whole image if the added detail helps.....

[Colin Southern]

If all else fails, run the desaturation brush over the fringe. In this case I just set the blues saturation channel in ACR to zero.

[ScoutR]

Wendy - I've just been having a chat with Tom, one of my Maine Coons. He doesn't believe a word of what you're being told about colour fringing. He points out, quite vocally, that what you are seeing is the cat's natural aura. Tom is of the view that if your cat finds out that you've captured his aura in a photograph, there may be pussy hell to pay! No more snaps at all, let alone flash. So, Tom thinks you should keep mum, chromatic aberration indeed!

Cheers

David (& Tom)

Ahhh yes, I think I remember Tom, he is the one who likes to hang around your computer and does not like to have his picture taken.
LOL, I like the aura explaination. It will be easier for me to look up the significance of a grey/blue aura than to learn all these PP terms and techniques.

I think the cat may already know about the aura being captured. I will have a talk with him and see if he will accept my apologies and adjust his behaviour which sometimes leaves a lot to be desired.

Thanks for the easy out, and chuckle
Wendy

[ScoutR]

I also would try to improve the situation...

I would treat the problem area as Haze.....select the area, add feathering, and run Unsharp Mask at a high Radius perhaps 50 then with curves touch up the selected area.......

You could also have run the USM over the whole image if the added detail helps.....

Thanks Willgloss: I have copied this method to the document. There seem to be a few solutions to this problem. I have quite a few old shots to practice on. and will turn them into a project for a rainy day.

Wendy

[ScoutR]

If all else fails, run the desaturation brush over the fringe. In this case I just set the blues saturation channel in ACR to zero.

Looks pretty good Colin, and sounds like something I would be able to do without too much studying. I've copied this to my document and will give it a try. I don't know if I have a desaturation brush with Elements ACR, (Just looked and I don't, I think there is something like this in the Editor though) but I'm pretty sure I should be able to do this kind of thing with the LR adjustment brush. Then the only problem is getting it done without being obvious.

Wendy

[ScoutR]

"I will try to translate this into Elements and have a go at it." - Difficult, that - PSE doesn't yet support Lab colour so I'm having a look at the GIMP, to see how easy it is there.

More later...

Peter

Thanks a lot Peter, the results are really quite good. I should be able to find something in Elements that will come close, but I'm pretty new to PP so I have to figure out all the terms and what is actually happening before I can give it a try. I really appreciate your help on this and will keep an eye on the thread in case you have found something that translates into Elements 8 or Lightroom 2.6. This will be a rainy day project for me, so if you come across something in the future, please post, I'll be watching.

Thanks again
Wendy

[proseak]

I don't know if I have a desaturation brush with Elements ACR,

I don't know either, but can tell you where it is in Elements - it's the "Sponge" tool, and shares a location with the "dodge" & "burn" tools. Just press "O", makes sure that you have the sponge, and set the mode to "desaturate".

As to my experiments withe the GIMP, my conclusion was that it was "doable" but fiddly; Photoshop proper does seem the way forward. You might find a copy of 6 or 7 kicking about that some kind soul will give you...

[ScoutR]

"I don't know if I have a desaturation brush with Elements ACR, " I don't know either, but can tell you where it is in Elements - it's the "Sponge" tool, and shares a location with the "dodge" & "burn" tools. Just press "O", makes sure that you have the sponge, and set the mode to "desaturate".

As to my experiments withe the GIMP, my conclusion was that it was "doable" but fiddly; Photoshop proper does seem the way forward. You might find a copy of 6 or 7 kicking about that some kind soul will give you...

Thanks again Peter: I didn't think it was in ACR, I will check it out in the Editor. I've never used the Sponge or Dodge and Burn tools. Might be a good area to focus on next. I know Photoshop is probably the way to go, but I don't think I need to move on until I understand all the controls I have now - what they do and when to use them.

[Colin Southern]

Thanks again Peter: I didn't think it was in ACR

Hi Wendy,

Just a quick clarification ... tool I used in my example is in ACR, but it's on the HSL / Grayscale tab which isn't available to those using PSE.

[ScoutR]

Hi Wendy,

Just a quick clarification ... tool I used in my example is in ACR, but it's on the HSL / Grayscale tab which isn't available to those using PSE.

OK, I figured it was probably a photoshop thing. I know you have more tabs and controls than I do in the Elements version of ACR

[Colin Southern]

OK, I figured it was probably a photoshop thing. I know you have more tabs and controls than I do in the Elements version of ACR

Time for you to upgrade Wendy ... as the Borg said in Star Trek ...

... "Resistance is Futile"!