Colour adjustment curve

[Playful_nature157F]

I dont have any scripting ability and thought of asking the community whether they can help in achieving the below goal.

I have a layered PSD file. I am applying two different colour profiles to the PSD file and save them separately as 2 PSDs. 

Image1.psd

Image2.psd

What we are trying to achieve is to equivalate the LAB values of each pixel through scripts from Image1 to Image2. The pixel size needs to be provided as a flexible number so that we can change according to images. Is this something that can be done?
Working mode can be LAB but not RGB. 

[Stephen Marsh]

I'm not understanding. Please list step-by-step what you are trying to do.

If you have an action that does most of the steps, then a script can either be used for one or more steps that are beyond the capabilities of an action... Or the action can be used as a guide for recreating as a script.

[Playful_nature157F]

1. I have a psd file, say image.psd. 

2. I am saving this into two images, image1.psd (applying the document working profile to Coated GRACoL 2006 (ISO 12647-2:2004) and image2.psd (applying the document working profile to Coated FOGRA39 (ISO 12647-2-2004).

3. Now when you review these two images, though they are same, some colour variation will appear due to the application of these working profiles.

4. To note down the colour difference, I position the eyedropped tool at various xy coordinates and noted the LAB values of both these documents.

5. I wish to make them both looking exactly the same except the working profile applied in the document and hence with to adjust Image2.psd to match Image1.psd from the noted LAB values. 

6. I have seen in this community that the LAB values of each pixel can be pulled out from a document and wish to try this to achieve the result of point no 5 through script.

Is this clear?

[Stephen Marsh]

My initial thought is that this doesn't sound like a good idea, however, let's see where this goes...

1. I have a psd file, say image.psd. 

What colour mode and profile is this document?

2. I am saving this into two images, image1.psd (applying the document working profile to Coated GRACoL 2006 (ISO 12647-2:2004) and image2.psd (applying the document working profile to Coated FOGRA39 (ISO 12647-2-2004)

What exactly do you mean by "applying"? Please use standard terminology so that things are clear.

If the answer to Q1 is RGB, then this would be Convert to Profile.

If the answer to Q1 is CMYK, then do you mean Assign Profile or Convert to Profile?

[c.pfaffenbichler]

My initial thought is that this doesn't sound like a good idea,

I think you are right, it sounds like the OP is trying to essentially reinvent Color Management. 

2. I am saving this into two images, image1.psd (applying the document working profile to Coated GRACoL 2006 (ISO 12647-2:2004) and image2.psd (applying the document working profile to Coated FOGRA39 (ISO 12647-2-2004).

Why are you calling these ICC Profiles/Color Spaces »working profiles«? 

[c.pfaffenbichler]

That pixels in an image separated in two different CMYK Spaces having different Lab-values does not seem particularly relevant. 

The Cyan, Magenta and Yellow (and even the Black and the paper-tone) of two such distinct CMYK Spaces are likely to be (however slightly) different and therefore certain colors may be out-of-gamut in the one but not the other.

What Intent did you use by the way?  

[Playful_nature157F]

The Colour mode is LAB. The colour conversion and adjustment is done to check in a GMG printout stimulating the Printer's profiles.

[c.pfaffenbichler]

What is the actual problem you are trying to address? 

Different CMYK Spaces have different »corners« (the primary colors, the blackest admissible black, …) and compressing an image from the largest-possible Color Space (Lab) into a commercial CMYK Space (which is necessarily smaller) will necessarily cause changes. 

What Intent are you using – Relative Colorimetric, Absolute Colorimetric, …?  

[Stephen Marsh]

The Colour mode is LAB. The colour conversion and adjustment is done to check in a GMG printout stimulating the Printer's profiles.

By @Playful_nature157F

So you have a Lab mode image, that you are converting to two similar but "competing" profiles used in the U.S. and the "rest of the world".

Whichever of the two CMYK conversions has the smaller gamut, convert to the larger gamut, experiment with both relative colorimetric with BPC and absolute colorimetric rendering intents.

Also consider the use of DeviceLink profiles if available for the source and destination conditions.

[c.pfaffenbichler]

You mentioned »layered PSD« – if you don’t merge before/at converting to the target space that could cause additional differences, could you please post screenshots screenshots taken at View > 100% with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible of the two CMYK-images?