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Author Topic: White Balance/Colour Cast Removal - CS4  (Read 3718 times)
Dinarius
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« on: March 27, 2009, 10:47:07 AM »
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Some time ago I shot an image under studio conditions of a piece of flat art.

The image also contained a basICColor Grey Card and a mini-Gretag CC.

After processing the TIFF (having made a basic white balance using the grey card) I noticed that the image had a slight cast when opened in CS4. So, I used the Grey Colour Picker in Levels on the grey card and this successfully removed it.

Yesterday,  I shot a detail of the same piece of flat art. But, because the client didn't want to waste pixels, I shot the grey card and CC seperately, but identically. I then applied the changes to the image and processed it.

However, when I open the image in CS4 I now have that same cast, but I don't have a grey card in it to use as a reference. So, if I was to apply the correction to the shot of the grey card, how can I then apply this to the art image?

Applying settings across images in ACR is simple, but how do I do this is CS4 to make the detail look the same as the earlier image?

Many thanks.

D.
« Last Edit: March 27, 2009, 10:54:54 AM by Dinarius » Logged
Jack Flesher
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« Reply #1 on: March 27, 2009, 11:21:17 AM »
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Quote from: Dinarius
Some time ago I shot an image under studio conditions of a piece of flat art.

The image also contained a basICColor Grey Card and a mini-Gretag CC.

After processing the TIFF (having made a basic white balance using the grey card) I noticed that the image had a slight cast when opened in CS4. So, I used the Grey Colour Picker in Levels on the grey card and this successfully removed it.

Yesterday,  I shot a detail of the same piece of flat art. But, because the client didn't want to waste pixels, I shot the grey card and CC seperately, but identically. I then applied the changes to the image and processed it.

However, when I open the image in CS4 I now have that same cast, but I don't have a grey card in it to use as a reference. So, if I was to apply the correction to the shot of the grey card, how can I then apply this to the art image?

Applying settings across images in ACR is simple, but how do I do this is CS4 to make the detail look the same as the earlier image?

Many thanks.

D.

1) first process both with identical settings in the raw processor;

2) open both converted files in CS4;

3) on the gray card image, add a levels adjustment layer, grab the gray dropper and click on your desired gray;

4) click and drag that levels adjustment layer from the panel directly on top of the art image and release.

5) you should now have the adjustment layer on top of your art image and assuming they were both shot in identical light at identical camera settings, the cast should be removed from the art image too.

HOWEVER...  The fact you have a different WB in CS4 than you do in ACR means you have a color management issue somewhere in your workflow -- I am guessing you probably need a good (or better) camera profile to apply in CS4, or a better dedicated capture profile for ACR...

Cheers,

« Last Edit: March 27, 2009, 11:26:38 AM by Jack Flesher » Logged

Jim.Batzer
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« Reply #2 on: March 27, 2009, 11:23:08 AM »
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If you are just using the gray eye dropper in the levels dialog, you can make the color balance change on a levels adjustment layer (as opposed to applying the levels adjustment directly to the background or image layer). Make this levels adjustment layer on the image with the color checker card. Next, open the image without the color checker card, and drag the adjustment layer from the first image to the second. It should copy over to the second image as an adjustment layer having the same color balance impact on the second image as it did on the first.

Hope that helps.

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David James Batzer

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« Reply #3 on: March 27, 2009, 11:24:45 AM »
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I like the post before mine with the nice user-friendly step numbers!

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David James Batzer

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www.batzerphotography.com
Dinarius
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« Reply #4 on: March 27, 2009, 11:50:45 AM »
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Ya learn something new every day!

Thanks guys.

D.

ps. Re Jack's point about profiles.........

What is different about the correction made by the mid-grey picker in a Levels Adjustment layer and the White Balance correction in ACR?

With the image open in CS4, the Info palette is giving a neutral reading off the grey card - as it should be, because it was neutralized in ACR - but, it still makes a further change (cast removal) that the White Balance tool didn't make in ACR.

Well?

Thanks again.

D.
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Jack Flesher
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« Reply #5 on: March 27, 2009, 03:09:33 PM »
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Quote from: Dinarius
Ya learn something new every day!

Thanks guys.

D.

ps. Re Jack's point about profiles.........

What is different about the correction made by the mid-grey picker in a Levels Adjustment layer and the White Balance correction in ACR?

With the image open in CS4, the Info palette is giving a neutral reading off the grey card - as it should be, because it was neutralized in ACR - but, it still makes a further change (cast removal) that the White Balance tool didn't make in ACR.

Well?

Thanks again.

D.


Huh?  IF the info palette in CS4 is showing your gray card as true neutral (meaning all channels at identical values) when you hover the cursor over it, then clicking on it with the gray dropper in the levels adjustment in CS4 should not change it.

Only possibility I can think of is that perhaps your CS4 gray dropper got reset in the Levels palette?  You can check this (and change it to any desired value!) by double-clicking on it in the levels palette. A dialog box then pops up that lets you adjust the setting; by default it should be 128/128/128.  Note also there is a common misconception that the gray dropper will adjust gray point to the exact level it's set as it does for the set white and black droppers -- it doesn't.  Instead, it adjusts the balance between the channels of what you clicked on to that balance parameter.  

Also switching to soft-proof mode or changing color models (like to CMYK) will alter the appearance of colors

Cheers,
« Last Edit: March 27, 2009, 03:12:58 PM by Jack Flesher » Logged

KSonde
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« Reply #6 on: April 01, 2009, 03:53:56 PM »
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Quote from: Jack Flesher
1) first process both with identical settings in the raw processor;

2) open both converted files in CS4;

3) on the gray card image, add a levels adjustment layer, grab the gray dropper and click on your desired gray;

4) click and drag that levels adjustment layer from the panel directly on top of the art image and release.

5) you should now have the adjustment layer on top of your art image and assuming they were both shot in identical light at identical camera settings, the cast should be removed from the art image too.

HOWEVER...  The fact you have a different WB in CS4 than you do in ACR means you have a color management issue somewhere in your workflow -- I am guessing you probably need a good (or better) camera profile to apply in CS4, or a better dedicated capture profile for ACR...

Cheers,

You can also open both images in CS4, create a Levels adjustment layer in the art image and reach over and click on the gray card in the gray card image. No dragging of layers is needed. Not a big deal---works both ways---just a little quicker.

Kurt
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