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P: Color Sampler handing by History and Action steps is inconsistent

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Explorer ,
Dec 19, 2022 Dec 19, 2022

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Hi there, this is my first message here.

I've experienced an issue since many versions of Ps and I was hoping someone fix it but at the end I realized it's better to search where to tell someone to fix... and I finally came here.

This bug is still there since Photoshop CS or so until today. I'm using Windows 10 x64 and now Ps 24.0.1

Steps to see it:

  • Open an RGB image
  • Go to the Information tool
  • Place a color sample anywhere into the image with the color picker sample tool (shortcut I and then shift+clic) (sorry I'm using the spanish version of photoshop, so no sure the english name of it)
  • Select Lab color in the drop-down list in the color dropper icon just beside the R,G and B values in the Info tool:

19-12-2022_13-01-13.jpg

 

BTW: In this very same drop-down list I bet 0-32768 is a small mistake, it should be 0-32767.

 

  • Do a color conversion from the actual color space to another one in RGB.
  • Go to History panel and go a step back. you'll see it automatically changes back to RGB instead of keeping Lab values. that's the bug.
  • If you change it again to Lab and go a step forward and then back again, you'll see the same behaviour.

I hope this helps you fix it. I know it's a small bug but sometimes when you're working with Lab values and readings it's very annoying.

Best regards from Barcelona.

Hugo
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correct answers 1 Pinned Reply

Adobe Employee , Dec 19, 2022 Dec 19, 2022

I've asked engineering to take a look. There are some inconsistencies on how history and actions handle the Color Sample color spaces. It looks like this maybe goes back to the days when this feature was initially implemented. I see the same behavior in CS6 which means it's even older.

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Engaged ,
Dec 19, 2022 Dec 19, 2022

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in the "Info Panel Options", if you change the First Colour Mode to Lab Color, does it still revert when converting to a new profile?

Info Panel Options.png

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Guide ,
Dec 19, 2022 Dec 19, 2022

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quote

BTW: In this very same drop-down list I bet 0-32768 is a small mistake, it should be 0-32767.


By @hurodal

 

No, that is actually not a mistake. Photoshop's 16bit mode is a 15bit +1 mode.

 

If it were a true 16 bit mode the range would be 0 through 65,535.

But in Photoshop (for legacy performance reasons back in the 90s when the 16bit mode was implemented) the actual range is 0 through 32,767 + 1, which made it simpler and more efficient to calculate with in Photoshop's code.

 

That means that 0-32768 is correct for Photoshop's 16bit mode.

 

In other image editors you'd see a range of 0 through 65,535.

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Adobe Employee ,
Dec 19, 2022 Dec 19, 2022

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I've asked engineering to take a look. There are some inconsistencies on how history and actions handle the Color Sample color spaces. It looks like this maybe goes back to the days when this feature was initially implemented. I see the same behavior in CS6 which means it's even older.


Senior Product Manager - Customer Advocacy - Digital Imaging
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Community Expert ,
Dec 19, 2022 Dec 19, 2022

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I can also replicate it on this end (PS24.1, the latest version of macOS). 

The sampler set to Lab reverts to RGB using the History step.

 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Explorer ,
Dec 22, 2022 Dec 22, 2022

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Thanks for the explanation. I was aware about that 15+1 bit but didn't realize it was related to that number.

BTW, if that's something related to the computer performance of the 90s, why don't they change it these days?

Hugo

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Explorer ,
Dec 22, 2022 Dec 22, 2022

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Thanks! I hope it's fixed in the next version.

Hugo

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Explorer ,
Dec 22, 2022 Dec 22, 2022

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No chris11235813, it doesn't revert. But anyway, the bug is related to the color sample's reading and not the actual reading of the pixel under the cursor.

Hugo

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Community Expert ,
Dec 22, 2022 Dec 22, 2022

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Nothing to do with the 90s and little if any reason to change. But you can post a feature request (as has been done with no result due to the above).

https://community.adobe.com/t5/photoshop-ecosystem-ideas/how-do-i-write-a-feature-request/idi-p/1238...

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Guide ,
Dec 22, 2022 Dec 22, 2022

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@thedigitaldogWell, indirectly the 90s are involved in that computer hardware at the time was still a limiting factor in processing images. It's a shame the old forum is no longer available, because I recall a thread where Chris Cox (former senior Photoshop developer) mentioned this in a long discussion about the technical decisions to limit Photoshop's 16 bit mode to a 15bit 0-32767 +1 range.

 

One of his responses was that the decision was a pragmatic one: much easier and more efficient to calculate with and performance friendly for the hardware at the time. This was years before the 32bit mode was first implemented.

 

And whether it matters if it is a true 16 bit mode or not: well, that depends on the user. Granted, a very small segment of users are hindered by it.

 

As far as I am aware layer effects are calculated at an 11bit (2048) range. And are selections still 8bit only in the current version? Does it matter? Depends. For most probably not.

 

As for the request: a request/bug thread for a full range 16bit mode was actually made years and years and years ago on the old request site - at least that's what I remember. I believe it was closed at the time for "being a feature and not a bug". I remember it fired a quite heated discussion.

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Community Expert ,
Dec 22, 2022 Dec 22, 2022

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Long before Chris’s post there was this from one of the original Photoshop engineers:

 

 

The high-bit representation in Photoshop has always been "15   1" bits (32767 (which is the total number of values that can be represented by 15 bits of precision)   1).  This requires 16 bits of data to represent is called "16 bit".  It is not an arbitrary decision on how to display this data, it is displaying an exact representation of the exact data Photoshop is using, just as 0-255 is displayed for 8 bit files.“
 
Getting back on topic: I can again confirm the bug ; Color Sampler handing by History and Action steps is inconsistent. Others who do should upvote.

 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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Guide ,
Dec 22, 2022 Dec 22, 2022

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@thedigitaldogYes, I am aware of that.

 

In the end users have to decide for themselves whether it matters to them or not. I work with 3D creation apps and a 32/16bit texturing and rendering pipeline. I prefer to keep my original 16bit data intact until the very end. So I had to switch to other image editing software to do so.

 

I'll stop bringing up and debating the topic in these forums from now on. Let's just agree to disagree, and users will have to decide for themselves if it impacts their workflow or not.

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Community Expert ,
Dec 22, 2022 Dec 22, 2022

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I prefer to keep my original 16bit data intact until the very end. 

 

What makes you sure that is not the case?

We don't have to agree. Adobe does and they haven't changed anything in over 30 years of PS. 

The burden of proof isn't on me to convince them otherwise either. 🤔

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

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