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18 Messages

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540 Points

Wed, Sep 14, 2011 5:29 PM

10

Common color samplers for Photoshop, ACR, and Lightroom

Add consistent RGB measurement capability among Lightroom, ACR, and Photoshop

There is not a common set the "Colors by the Numbers" approach in these 3 applications. I would prefer that they all shared at least one common methodology. Ideally this would be LAB measurements yet it would be a big step forward to have a consistent format (percentage or number) in a common RGB color space.

As it stands here are the differences

Lightroom: Has no color samplers and the RGB measurements are made in percentage format in an unspecified RGB Color Space

ACR: Has color samplers with number format (0 to 255) and the numbers tied to the Color Space that is being used with that image (as opposed to an option to read in LAB which is fixed values and not subject to changes across multiple color spaces

Photoshop: Also has color samplers and the color information can be displayed in a wide variety of Color Spaces (including LAB) and number formats e.g. 8 bit, 16 bit, 32 bit (yet not percentages for RGB similar to Lightroom).

My preference would for all three to have color samplers (adding them to Lightroom) and the ability to measure/view the numbers in LAB space which would be consistent in all 3 applications as well as other Adobe and non-Adobe applications.

Responses

704 Messages

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8.5K Points

9 years ago

Lightroom references RGB off of ProPhoto RGB with a tweaked gamma.

18 Messages

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540 Points

9 years ago

Hi John and thanks for your inputs. Let me show with an experiment how your inputs confirm the problem.

Take a solid color TIFF image with LAB in Photoshop = 60/24/23
This is the same as ProPhoto RGB in Photoshop/ACR = 148/117/92
Which displays in Lightroom as = 66.1%/54.6%/44.8%
When multiplied by 255 for a number scale = 169/139/114

Even when if I mostly used Lightroom and got used to their percentage scale, if I Edit in Photoshop as a Smart Object and then edit that Smart Object it goes to ACR with a different RGB scale (and only in ProPhoto RGB if I leave it in that Color Space)

I had heard that Lightroom had used a modified ProPhoto RGB space so thanks for that confirmation of the Gamma change (which amount is unspecified).

My point is that even if the Gamma number was specified, why in this day and age of computers and these products all being under the roof of one company, what not have a common measurement among the three as an option. It would make my life/work a lot more productive. All I want is to match colors among the three applications with a common measurement format and space.

Thanks again for your inputs.

946 Messages

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13.8K Points

9 years ago

"I had heard that Lightroom had used a modified ProPhoto RGB space so thanks for that confirmation of the Gamma change (which amount is unspecified). "

LR uses ProPhoto primaries with an SRGB tone curve.

18 Messages

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540 Points

9 years ago

Thank you Lee. What would you recommend as the best way to take a ProPhoto RGB set of numbers from Photoshop/ACR and translate that to the percentage RGB numbers in Lightroom that I want to target with another image? That would be interesting as a workaround yet I don't see the productive path to come up with the numbers. I am open for inputs on the most productive workarounds in parallel with Adobe considering my change request.

1.5K Messages

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19.8K Points

9 years ago

You can build Melissa RGB (what LR uses) in Photoshop and load it there assuming you think its all that important to have the same numbers scaled to 0-255 in Photoshop. Just go into the Color Settings. Load ProPhoto RGB in the RGB Working Space and then click on Custom. Update the Gamma encoding to 2.2, save with a new name.

Until such a time that Photoshop (and ACR) have a switch to update the scale from 0-255 to percentages, there is going to be a mismatch. Personally I think a percentage scale makes far more sense, is easier for newer users to understand. If you recognize with either scale what is a clipped highlight (255 or 100%) and black (zero or 0%) and know that equal values of all three is a neutral, I'm not sure why anyone needs to know a value being converted into the other. Yes, it would be really nice if we could select via a preference in all three applications what we wish to see and could keep all three in sync.

The question to ask yourself is, what are you doing with the numbers? What are you expecting them to tell you. Do you need to know what the numbers will become after you render the raw and bring it into Photoshop (ACR lets you do this in a limited way with only four color spaces). LR lets you do this with far more possible color spaces but will not sync with Photoshop. Parity among all the app's would be most welcome.

And yes, ACR gives us what, 9 samples, Photoshop only 4 and LR none. Can we have 9 in all three (and control the sampling?).

Author “Color Management for Photographers"

173 Messages

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3.8K Points

9 years ago

Looking for an "Under Consideration" tag for this. Seems obvious.

18 Messages

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540 Points

9 years ago

Hi Andrew
Thanks for the pointer to Melissa RGB and more importantly your weight on getting attention on this change request.

I am fine with using RGB percentages as long as they are all referenced to the same color space. A high want would to be able to have the measurement format/color space match with non-Adobe products. I just want one common way to measure and read with color samplers across the 3 applications. As mentioned in my previous post this is typically not needed for one image across all 3 applications. The primary need is for a common approach for all three apps for separate images with color adjustments at different points in the workflow. Plain and simple the need is for ease of use.

Thanks Scott for your support as well in this request.

1.5K Messages

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19.8K Points

9 years ago

>I am fine with using RGB percentages as long as they are all referenced to the same color space

The problem is, the histogram is based on something you are not getting out of LR (but could). If you built that custom profile, you can export to that space from LR (but not ACR). I’m not sure you’d want to however. I think ProPhoto was pretty well researched years ago, the selection of the gamma encoding wasn’t done without some thought. Then, even if you exported in MelissaRGB, you would not see the same scale in Photoshop. I really think Photoshop should provide 0-100% scaling as an option. So should ACR.

For many years I’ve asked the various Adobe teams to just give ACR/PS/LR parity in terms of the number scales and histograms. So the suggestion gets my vote big time.

Author “Color Management for Photographers"

23 Messages

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614 Points

9 years ago

Usually, for correct the withe balance, is very usefull read the Lab color coordinat of an image, so is very usefull if is possible to add some color check (like to photoshop) with the color coordinate in differente scheme (RGB/CMYK,LAB...).

This reply was created from a merged topic originally titled
Is it possaible to add the Lab color coordinate in lightroom info?.

1.5K Messages

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19.8K Points

9 years ago

You don’t need Lab for WB as when all three value (in any area of the tone scale, 0-100% or for that matter 0-255) are equal, it is neutral.

Author “Color Management for Photographers"

23 Messages

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614 Points

9 years ago

In LAB mode there are also some rule in a and b parameter for other part of the image, not only neutral part. And is very hard to translate this rule from RGB to LAB. So in some images were I want to set a good WB for the skin tone, or for the sky, or... the LAB coordinate is usefully.

1.5K Messages

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19.8K Points

9 years ago

What rules specifically?

Yes, for those used to working in Lab or another color model, it might be difficult to translate into RGB or vise versa. Lots of people complain about the percentage scale for values in LR. usually people who’ve been using the 0-255 scale for a long time. For newer users, it is far easier to teach them percentages. After all, how is 255 being the whitest white easy to understand compared to 100%?

Author “Color Management for Photographers"

23 Messages

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614 Points

9 years ago

When you move the cursor temperature and tint, for adjust the WB you are working the two coordinate "a" and "b" of the lab. Temperature is like "b", and tint is like "a". So, have an information that show how this parameter are moving in an specified part of the image can help. I understand that the "standard" user don't know the Lab space, but for everyone that have some knowledgment of the colorimetry, this feature can help because in Lab you divide the color information from the luminositi information.

About the rules.
For example an interesting rules for the skin is:
b > a and "6 < b < 28"
Try to verify this rule. It's very usefully, for have good skin color.
This isn't only a math rules, because, the skin of a baby is different from the skin of an old man, but it's very interesting.
By starting from this rules you can balance tha image for the skin, or obtain other particular effect.

1.5K Messages

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19.8K Points

9 years ago

Elia, it is true that the Tint and Temp sliders affect the WB like the aStar and bStar direction. But other than moving WB magenta/green Yellow/Blue, I don’t see how you’d correlate that to actual Lab values and where that be too useful (but I’m open to suggestions).

As for skin, you can just as easily build rules in RGB with percentages. See:
http://digitaldog.net/files/LR_Skinto...

There is a very well defined ratio of RG&B here using well known high quality renderings of skin (eg Roman16 reference images among others).

Author “Color Management for Photographers"

6 Messages

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130 Points

6 years ago

This reply was created from a merged topic originally titled CMYK values in ACR.

It would be nice if you could see CMYK values in ACR without making change in the colorspace settings. I have many times forget to change the colorspace back to RGB.