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Old Jul 27, 2004, 10:52 AM   #11
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:homey: This is a standard method that is often used. The problem with it is that it is global. I have a photo of the cab of a steam engine with noticeable fringing on a pressure gauge where there is high contrast between the gauge and the background. The Engineer is wearing a blue/purple boiler suit. With my method I clear the fringing without affecting any other part of the picture. Using your method, the fringing disappears but the boiler suit becomes grey.
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Old Jul 27, 2004, 10:41 PM   #12
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I just tried my method

image-adjustments-hue/saturation-blues-(-80) with a marquee around the area in need of adjustment.This elliminates the affect on the whole image. I'm just learning photoshop and I think this solves the problem you adressed, I could be wrong though if I misinterpreted your reply, let me know.

Thanks
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Old Jul 28, 2004, 5:00 AM   #13
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:homey:Hi Timothy

You`re quite correct. That does work. I just find that the other way eliminates the need for selections.

Cheers

Graham
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Old Sep 3, 2004, 5:50 PM   #14
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Hi everyone,

Graham and Thimothy both have a point, but both are not on the right spot either.

The key to succesfull work in Photoshop (or any other image-editor) is in creating the right selections. That what Timothy was pointing at. Graham had a good point adjusting the saturation in the blue channel.

The trickthe Photoshop-guru'suse in our advertising agency is this one.

First create the right selection; i.e. the spots where purple fringing occurs.
The best and the easiest way we know is to zoom into the problem area. Something like 500% will do. Choose Select > Color Range. Choose "Sampled Colors" from the menu. With the eyedropper (+) tool you click the most dominant colors of purple fringing. You will immidiatly see in the preview window what you are selecting. This action will select every pixel in the entire image that have the same color values. So by cleverly clicking on one spot you will be able to select most of the fringing in the entire image in one mighty blow.

This selection has a hard edge, something that fringing does not have. So you go to your menu again and choose Select > Feather. Choosing a feather value of one, two or three pixels will be OK, depending on the resolution of your image.

You now have a nice selection of most of the fringing in your image with nice soft edges.

Now press Ctrl+H to hide the selection. The selection is still there, but when you are not distracted by a screen full of "Walking ants" you will have a better view of what you are doing.

And then it is time to go to Grahams idea and downscale the saturation in the blue channel.

This way you have all the advantages without all the tedious handwork Grahams method requires.

I made a small example of this method applied to a 8 megapixel shot of a harbour crane with purple fringing all over the edges of the hundreds of steel things in this picture.

Removing it cost me exactly 2 minutes.

For educational purposes i made a mistake. Ik "forgot" something. Look carefully at the example.

And this illustrates the second problem i have with Grahams idea. If you adjust the saturation, you also unwillingly change the density of the image. Doing that in a global manner on the entire image leaves you with an unnatural result.

In my example it is pretty clear the pixels in the places where the purple fringing is removed are lighter, whichthey arenot supposed to be.

Therefor don't forget to apply the third step. While you adjust the saturation, make sure you compensate the density with the Lightness-slider just underneath that. You will see that you will be able to archieve a prefect result without any traces left.

Succes!

Tjerk Heringa

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Old Sep 4, 2004, 3:05 AM   #15
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:homey:Hi

I think Tjerk misses my point. I listed a method to remove fringing without selections.

Unless you have a particular reason to do so it seems much simpler to set up the layer and wipe out the fringing with a brush. There`s no selection, zoom 500%, go back etc. It seems too complicated for me. Maybe a full time guru has no problem as he`s doing it all the time but I think that in the majority of case it `s using a sledgehammer to crack a nut. After all fringing only occurs in parts of the image.

Cheers

Graham
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Old Sep 5, 2004, 12:45 AM   #16
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Thanks Graham,

i was just trying to show a way that is failsafe, fast, easy and gives a perfect result. In my work we need solutions that work fast and efficient. In the end it is all about user-preferences. In Photoshop there are a thousand ways to skin a cat.

Greetings,
Tjerk
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Old Sep 5, 2004, 3:44 AM   #17
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:homey:Thanks Tjerk

My problem is I teach Photoshop (and other things) to people who have difficulty in finding the on/off switch. So you can see where I`m coming from.

Regards

Graham
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Old Sep 19, 2004, 7:04 AM   #18
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I've been using a Nikkormat and 35mm since 1974. I bought my first 'digital camera'

(a small 1 mpg Olympus) 18 months ago. I rely on this website to learn about digital

equipment.

This week I purchased a Panasonic Lumix F20 and got purple fringe on the 3rd shot:O:?.

I'd read about it before but didn't really think much about it before.

I am glad to see two different ways to go about fixing it (from Grahm and Tjerk).



Thanks !


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Old Oct 5, 2004, 5:40 PM   #19
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You don't need layers or eyedroppers, or change the hue or saturation.

There's a simpler and more effective method:

Here a 10x enlargement taken with a 2x teleconverter on a digital camera, showing gross purple fringing:

http://darb.net/photos/anonymous/P1020726b.sized.jpg


Here's the same shot with some processing done. The shot can be done even better, to get rid of the blue fringing as well. I also processed it as a JPEG, but TIFF would have been better.

http://darb.net/photos/anonymous/P1020726d.sized.jpg


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Old Oct 6, 2004, 6:21 AM   #20
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Here is another example before and after, this time magnified more, right in the very corner:

http://darb.net/photos/anonymous/P1020726x1.jpg

http://darb.net/photos/anonymous/P1020726xx1.jpg
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