Colour Card Image Matching

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jacktorrance
Posts: 4
Joined: Tue Dec 24, 2013 12:16 am

Postby jacktorrance » Wed Dec 25, 2013 12:29 pm

Hi,

I have a series of photographs taken with colourcards next to the content. The colour cards are black, mid grey and white.

The photographs have been taken with exactly the same setup although when I use the eye dropper tool in PS the RGB values of the colour cards are slightly different. I suspect that light might be bouncing off different things in different images, the minor differences aren't that surprising. However, I need to make the colour card RGB values in all images exactly the same, and automate the process as there are hundreds of images.

I'm new to Curvemeister and wondered whether anyone can help with a workflow? I can't get my mind around how to apply the settings to all images so that the RGB values come out exactly the same for the colour cards every time.

Many thanks in advance

ggroess
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Joined: Wed May 24, 2006 2:15 am
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Postby ggroess » Wed Dec 25, 2013 2:13 pm

Jack,

If the lighting is consistent I would do the following:

1) pick an image that represents the majority of the images and set a hue clock on each card in the frame.  "Alt-click" on the spots you want hue clocks

2) Using the RGB color space adjust the curves to make the image look it's best using a by the numbers correction.  See this video for more info on By the Numbers.  http://youtu.be/2AjTi78Bl7Y

3) When you have the image where you want it; save the curve to the desktop.  to do that click the "save" button and CM will open a "save as" dialog box.  Save the curve ACV file to the desktop and then apply the curve to the current image.

Finish the image.

Then...

To apply the previous curve that you saved to a new image; you click on the load button in CM and navigate to the desktop and select the ACV file you saved there.  Click OK and your image will have the curves applied.  You can then fine tune the correction a bit and move on to the next parts of your process. 

Rinse repeat for all images that are from the same lighting set up.

Keep asking questions... and let me know if that does not work for you there are other ways as well.
Greg

jacktorrance
Posts: 4
Joined: Tue Dec 24, 2013 12:16 am

Postby jacktorrance » Wed Dec 25, 2013 2:29 pm

Greg,

Thank you for your thorough reply - is there a way to automate so that the saved curve does not need to be manually applied to each image? Ideally I'll save a curve file which can be applied to hundreds, potentially thousands, of images at a couple of clicks?


-default
Posts: 1916
Joined: Thu Mar 26, 2015 1:53 am

Postby -default » Wed Dec 25, 2013 2:39 pm

Hi Jack,

Greg's procedure will work for each set of images with similar RGB color readings.  This may be what you want for each combination of subject / lighting. 

If you save the samples as an edr file, then you will be able to save the location and RGB values for each of the samples.  The edr file contains the locations and desired RGB values for the set of points on the card. 

Loading this into curvemeister will generate a set of sample points whose target values are  is specific for that particular image.  I have not yet tried scripting this operation so that it happens automatically, but it, or something very close to it, *should* be possible in Photoshop.  I will set aside some time to try this perhaps later today, or family activities on the holiday may push this back.

This is an interesting operation, that I think might be of general interest, and I think we can help accomplish it.

Mike


jacktorrance
Posts: 4
Joined: Tue Dec 24, 2013 12:16 am

Postby jacktorrance » Wed Dec 25, 2013 2:44 pm

Great, thanks Mike.
Happy holidays...!!

Jack.

ggroess
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Joined: Wed May 24, 2006 2:15 am
Contact:

Postby ggroess » Wed Dec 25, 2013 6:48 pm

another option might be to apply the curves to all of your images using the Ctrl F feature of Photoshop. 

So long as you use no other filters in between PS will reapply the last filter to what ever image you have open and active.  I frequently open 10 or more images in PS, correct the first one, then click on each one and press Ctrl-F to apply the filter. 

Touch all 10 images then move on.

Greg

jacktorrance
Posts: 4
Joined: Tue Dec 24, 2013 12:16 am

Postby jacktorrance » Wed Dec 25, 2013 8:14 pm

I wonder whether an action could be set up and applied to all images in a particular location.
I suspect that recording the Ctrl+F command and applying that would work as you suggested.

Thanks!


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