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OPR Workshop Information Exchange => Photoshop Discussion => Topic started by: Jonas.Wendorf on June 01, 2012, 10:00:52 AM

Title: Color cast correction - Action
Post by: Jonas.Wendorf on June 01, 2012, 10:00:52 AM
Hi there,

as posted here: http://www.operationphotorescue.org/forum/index.php/topic,3722.msg33369 I wanted to share with you and explain my color cast correction action, which you can download here: https://dl.dropbox.com/u/7124285/Foren/Operation%20Photo%20Rescue/Color%20cast.atn (if you're having trouble downloading, right click, "Save as")
Since the action works similar to using the neutral gray eyedropper in curves or levels, it can only correct single casts, so casts from multiple light sources won't be corrected. Also the correction is global, selective work and fine-tuning might still be needed.
Having said all that, let's get started :-).

To start I'm going to simply run the action on one of the images from the archive:
(http://www.abload.de/thumb/fishk7_8x10-6-16gjpt.jpg) (http://www.abload.de/img/fishk7_8x10-6-16gjpt.jpg)
Remember, this is just with the action, no user-interaction was required so far.

Now what the action does is actually pretty simple, but I added a few bits and pieces to improve the technique which makes things a little more complicated.
First what I did was run auto-levels and set the mode to "Color", the opacity to 60%. Why? Because I noticed that just running auto-levels gives me too much color most of the time, so I reduced the color enhancement part to 60%. If you want more color, increase the opacity, if you want less, decrease it.
Now the levels adj. is copied and set to "Luminosity" mode with 100% opacity. This sets the black and white points.
Next comes the actual color correction. The image's negative is stamped on a new layer and then the average color of this layer is found. Once this is done, the layer is blended in "Overlay" mode, which reduces the average color of the image most in the midtones and less in the shadows and highlights (so it corrects your usual cast).
Dan Margulis once said that usually images' averages are not completely neutral, but a little on the yellow side, so what I did next was blend a 54L, 0a, 5b into the mix to add a little warmth to the image (this was actually recorded in LAB mode to get the numbers right!).
The problem now is that the image brightness changed a little, so what I did was place yet another layer on top, fill it with 50% gray and blend in "Luminosity" mode to restore the original (improved by auto-levels) luminosity (this was recorded in 32bpc mode, so that it won't throw off 16bpc or 32bpc images).
Now if you need additional changes, you can put them on top, do your selective changes, increase/decrease opacities, play with the mode of the "Average" layer (anything from "Soft Light" to "Linear Light" will work, but "Overlay" works best for most images in my experience) or simply run the action again and reduce the opacity.

Personally I use this action as a starting point, but I always make sure to double-check my values afterwards and don't rely just on it.

I hope this helps some of you and if you have any questions or trouble running the action, just let me know :-)!
Title: Re: Color cast correction - Action
Post by: Mhayes on June 01, 2012, 11:46:31 AM

Thanks for a terrific tutorial---have bookmarked in my favorites. I love your detail and the reasoning behind each step. I not sure about the 2nd link as when I do a "Save As" and then try to open the file is not recognized with the ATN File. What am I doing wrong?

Thanks again!

Title: Re: Color cast correction - Action
Post by: Jonas.Wendorf on June 01, 2012, 11:55:47 AM
Hi Margie,

thanks for your nice feedback :)!
Maybe when you tried to download the file, another extension was added to it?
If so, try renaming the file to anything.atn, instead of maybe anything.atn.txt or whatever it is called now.
Or try using the flyout menu in the actions panel to load the action, that should work as well.
I've also uploaded the action in a ZIP archive here, maybe that'll work better: https://dl.dropbox.com/u/7124285/Foren/Operation%20Photo%20Rescue/Color%20cast.zip
Title: Re: Color cast correction - Action
Post by: glennab on June 01, 2012, 01:21:08 PM
Here are a couple of color correction references that I found in one of my LinkedIn forums.  If they're helpful, maybe we can move them to tutorials.

Using curves:
http://graphicssoft.about.com/gi/o.htm?zi=1/XJ&zTi=1&sdn=graphicssoft&cdn=compute&tm=189&gps=464_564_1489_971&f=20&tt=14&bt=0&bts=1&zu=http%3A//www.luminous-landscape.com/tutorials/command_primer.shtml (http://graphicssoft.about.com/gi/o.htm?zi=1/XJ&zTi=1&sdn=graphicssoft&cdn=compute&tm=189&gps=464_564_1489_971&f=20&tt=14&bt=0&bts=1&zu=http%3A//www.luminous-landscape.com/tutorials/command_primer.shtml)

Using LAB:
http://designfestival.com/transform-your-images-and-create-bolder-better-colors-with-photoshops-lab-color-mode/ (http://designfestival.com/transform-your-images-and-create-bolder-better-colors-with-photoshops-lab-color-mode/)

The LAB description is a little extreme, but then we do get some extreme color issues, so I thought I'd add it.  The question in the thread was how to make colors look "amazing."  Of course it pertained to pristine photos being retouched, but I find that even in those discussions I often glean little gems that help with color problems in our restorations. Hence, while these two discussions may not be useful to what you're doing right now, they may help in a later "work of art."

Title: Re: Color cast correction - Action
Post by: G3User on June 01, 2012, 10:22:06 PM
Jonas, the .zip file is good and I had no problems installing in CS3

However. when I run it I can't see any result from Auto-levels color or Luminosity and they don't appear to be an option in CS3.

Are you using a later version of Photoshop?

Title: Re: Color cast correction - Action
Post by: Mhayes on June 02, 2012, 01:10:11 AM

Thanks, I got it to work just fine, in fact I now have the action listed 5 times, so I must have had it and didn't realize it. This works pretty slick and thanks for letting us download it.

Title: Re: Color cast correction - Action
Post by: kelpie on March 13, 2014, 11:56:30 AM
Does this action still work OK in PS CC?

Title: Re: Color cast correction - Action
Post by: Mhayes on March 13, 2014, 02:53:59 PM
Sorry, no idea as I'm on CS5. Try it and see.

Title: Re: Color cast correction - Action
Post by: Jonas.Wendorf on March 14, 2014, 02:24:32 PM
I'm using CS5 as well, but as far as I know actions should be upward compatible, meaning that actions recorded for older versions of Photoshop should still work on newer versions (although the opposite might not be true depending on which options you use).