Missing CIE L*a*b* color readout – a real workaround

Discussions, questions, comments and suggestions regarding Capture One PRO, Capture One PRO(For Sony), Capture One DB and Capture One Express(For Sony) 9.x

Missing CIE L*a*b* color readout – a real workaround

Postby Bryce » Mon Aug 29, 2016 1:47 am

A small, inexpensive Mac OS X app called Classic Color Meter reads system-level color surprisingly accurate, and with the new version 1.8, launched just yesterday (Aug 27), it now features a floating mini-window that fits the Capture One user-interface perfectly.

https://www.ricciadams.com/projects/classic-color-meter

Info for photographers and Capture One users regarding color accuracy for can be found under the section: Frequently Asked Questions.


Background:

I switched from Aperture to Capture One in December and immediately contacted Phase One Support to learn how to change the setting for the color value readout, from RGB to L*a*b*. I was informed that only the Cultural Heritage version offered this. What?! Every major image editor has offered L*a*b* readout for years. (Also known as Lab color, without the asterisks, for someone who might use the forum's search function in the future.)

As a portrait and fashion photographer, I had grown accustomed to L*a*b* especially for skin tone adjustments, in both Photoshop and Aperture. L*a*b* has the huge advantage of specifying color and luminance as separate components and is therefore more intuitive to use when adjusting skin tones to be pale or dark, yellow or red, more or less saturated, etc.

In searching for a solution, I remembered Apple’s Digital Color Meter from many years ago and wondered if it might be the ticket. Sure enough, it could be set to display L*a*b* color values, but the user interface was problematic:

- The display window wouldn’t float above Capture One

- The display window was unnecessarily large and cluttered

My continuing search led me to Classic Color Meter (CCM), an improved and much expanded takeoff on Apple’s meter, but the interface was similar. I contacted the author in early July and he was happy to add a floating mini-window that would fit right into the Capture One user interface.

The result is a real pleasure to work with, in my opinion, and it’s wonderful to be back in control of the color in my images!

Below are two screen captures which show the floating mini-window in situ in Capture One. It can be placed anywhere, and fits nicely right over Capture One's RGB readout.

Image

Image

Below is an image of a ColorChecker with both Photoshop and Classic Color Meter readings. This shows the accuracy of CCM. The color values listed reflect my particular equipment profile combination: a Canon 7D camera profile in combination with a NEC PA272W (wide gamut) display profile. You can read under the FAQs about the relevance of the camera and display profiles. To view the whole image, save it first (drag to the desktop).

Image

Though CCM's accuracy decreases with increased color saturation (because the user’s display profile is generally smaller than the user’s camera profile), skin tone measurements are only slightly in error (less than 0.5 percent). In my image processing workflow absolute accuracy (greater than 0.5 percent) isn’t required, as I am concerned with how my adjustments are influencing the final skin tone color. So it’s the change from my starting to ending values that are crucial, and then of course knowing where the final values land.

Unlike the Capture One eyedropper, the CCM aperture (sampling size) can be adjusted from 1 x 1 pixel to 120 x 120 pixels. For skin tone adjustment this is a big bonus as a sample size of approx. 7 x 7 pixels gives a much more accurate, average color reading, being only slightly affected by dark pores or temporary color-changing skin conditions.

The main window (not the floating mini-window) shows the sampled area. I prefer to leave it at 8x magnification (adjusted from the View menu) and the aperture slider at the 4th mark from the left. This creates a 7 x 7 pixel sample size. If you have the display real estate (dual monitor) it can be handy to leave the main window open to be able to adjust sample size on the fly. The main window is also where you can change the color readout settings to:

RGB, percentage
RGB, decimal, 8-bit
RGB, decimal, 16-bit
HSB
HSL
and a few others

Disclaimer: Other than working with the author of CCM to suggest the changes made to better accommodate us Capture One users, I have no affiliation whatsoever with CCM or its author. This means (unfortunately) I receive no profits from the sales of CCM.
Last edited by Bryce on Fri Sep 09, 2016 3:21 am, edited 2 times in total.
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby tenmangu81 » Tue Aug 30, 2016 8:37 am

Thanks Bryce !! A good improvement of the former Apple tool !! Works perfectly.
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby Bryce » Tue Aug 30, 2016 9:19 am

Tenmangu81, glad to read that you've implemented the use of CCM with success.

May I ask how accurate your color readings are compared to Photoshop (in Lab), or to Capture One (in RGB)? How do they compare with my ColorChecker values (above)?

May I also ask what equipment you are using, as this determines the accuracy. Which camera model? Which display? And which profiling hardware (probe) and software?

Thanks.

Just for the sake of clarity, Classic Color Meter is a totally separate and unique program from Apple Digital Color Meter. You'll find Apple Digital Color Meter in your Utilities folder, as it has been for the past decade, or more.
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby PhaseoneUser55657 » Tue Aug 30, 2016 12:29 pm

The only thing I see wrong with it, is all the program can determine is the Pixel on the screen. Not the actual pixel value, you have it as it goes through all the "Color Correction" and stuff as the pixel makes it way to the display.

Robert
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby tenmangu81 » Tue Aug 30, 2016 2:38 pm

Hi Brice,

Photoshop gives me the same values as yours. But CM gives me slightly different values, especially on my calibrated display, which seems to me to be normal.
I have a Leica M (ref. M240), I use a (hardware) calibrated display NEC PA242. I use basICColor Display for the calibration software, and the probe is an x-rite i1 Display Pro.
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby Bryce » Tue Aug 30, 2016 10:10 pm

The only thing I see wrong with it, is all the program can determine is the Pixel on the screen. Not the actual pixel value, you have it as it goes through all the "Color Correction" and stuff as the pixel makes it way to the display.


Robert, yes, this is a workaround, as explained above. Do read CCM's author's simplified explanation (at the above link) about this issue, and if you're up for it, read a much more detailed explanation about the various color transformations that occur from the actual image color values through to the display buffer:

https://www.ricciadams.com/articles/osx ... nversions/

Only Phase One can give us a scientifically accurate L*a*b* color readout, but they've decided to keep it hostage to the Cultural Heritage version. But unless you need scientific accuracy, CCM does a fantastic job. Give it a try and then let me know what you think!
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby Bryce » Tue Aug 30, 2016 10:21 pm

Photoshop gives me the same values as yours. But CMM gives me slightly different values, especially on my calibrated display, which seems to me to be normal.
I have a Leica M (ref. M240), I use a (hardware) calibrated display NEC PA242. I use basICColor Display for the calibration software, and the probe is an x-rite i1 Display Pro.


Thanks for the feedback, tenmangu81.

Yes, you will get slightly different L*a*b* values via CCM because your camera and display are different than mine. The question for you to answer is whether or not the level of L*a*b* readout accuracy is acceptable for your image processing, or not. As I replied to Robert, unless you need precision to within tenths of a percent, CCM does an amazing job, especially for those of us with a wide gamut display.

By the way, I also use basICColor Display together with a i1 Display Pro. It's a great combination and allows me to create a number of profiles for my various needs: prints for indoor viewing, soft proofing for offset press, web design, etc.
Last edited by Bryce on Wed Aug 31, 2016 6:01 pm, edited 1 time in total.
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby tenmangu81 » Wed Aug 31, 2016 8:18 am

..... and I have compared the values (RGB or L*a*b*) given by Classic Color Meter with the standard Apple tool. The former (CCM) gives me far better values (I mean when I use PS or C1 as reference). I can trust it, and made me realize that I used for a long time the Apple tool which gave me poor values without knowing.
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby Bryce » Wed Sep 07, 2016 10:33 pm

Classic Color Meter has access to the same system-level display buffer values as Apple’s Digital Color Meter, so in theory their readouts should be identical for both L*a*b* and RGB, the author has informed me.

I did some testing and you’re right, CCM appears to be more in tune with Photoshop than Apple’s meter. As an image editor, Photoshop has of course access to the actual image pixel color values, which CCM and DCM don't.

You may or may not be aware, but it’s critical that CCM be set to the right readout setting to get accurate results. For L*a*b*, there is only one choice, so that’s easy. But if you decide to use CCM for RGB percentage, HSB, HSL, and other color models, it’s important that the wording which is written in gray below the R, G, and B readouts, is set to “Display -> sRGB”. Hover the cursor over it, and you’ll see it’s a drop-down menu. The correct setting is the top one.
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Re: Missing CIE L*a*b* color readout – a real workaround

Postby tenmangu81 » Thu Sep 08, 2016 9:38 am

Bryce wrote:But if you decide to use CCM for RGB percentage, HSB, HSL, and other color models, it’s important that the wording which is written in gray below the R, G, and B readouts, is set to “Display -> sRGB”. Hover the cursor over it, and you’ll see it’s a drop-down menu. The correct setting is the top one.


Thanks for the trick !!
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