Apple Pro XDR Display color gamut P3-65

[lwmsmd]

When using this display and color space above, is it best to convert a photo taken in the Adobe RGB 1998 space to an image with the profile "Image P3" to match the gamut of the monitor? Or is it best to leave the photo in Adobe RGB and expect to have some "clipping of colors?" I have read that the profile P3-65 represents about 85% of the colors available in Adobe RGB. This appears to especially confusing when I try to print an image.

[TheDigitalDog]

Short answer; doesn't matter. You've got some RGB working space and it is tagged; you're done. If you need to post it to the web and the browser isn't color managed, convert to sRGB (no guarentee of proper viewing but the safest option). The less conversions, the better. 

[lwmsmd]

Thanks. I'm most concerned with print accuracy. Matching what I see on my monitor versus what comes out of the printer. I'd love to see your article referenced "Color management for photographers..." and " "Photoshop CC Color management". Can you point to their locations? Thanks again. 

[TheDigitalDog]

If your concern is printing:

The benefits of wide gamut working spaces on printed output:

This three-part, 32-minute video covers why a wide gamut RGB working space like ProPhoto RGB can produce superior quality output to print. 

Part 1 discusses how the supplied Gamut Test File was created and shows two prints output to an Epson 3880 using ProPhoto RGB and sRGB, how the deficiencies of sRGB gamut affect final output quality. Part 1 discusses what to look for on your own prints in terms of better color output. It also covers Photoshop’s Assign Profile command and how wide gamut spaces mishandled produce dull or oversaturated colors due to user error. 

Part 2 goes into detail about how to print two versions of the properly converted Gamut Test File file in Photoshop using Photoshop’s Print command to correctly setup the test files for output. It covers the Convert to Profile command for preparing test files for output to a lab.

Part 3 goes into color theory and illustrates why a wide gamut space produces not only move vibrant and saturated color but detail and color separation compared to a small gamut working space like sRGB. 

High Resolution Video: http://digitaldog.net/files/WideGamutPrintVideo.mov

Low Resolution (YouTube): https://www.youtube.com/watch?v=vLlr7wpAZKs&feature=youtu.be

[lwmsmd]

Thanks. I'm on it. 

[NB, colourmanagement net]

@lwmsmd As DigitalDog wrote, it's up to you. Personally I'd leave the image in its original colourspace because every transformation between colour spaces is potentially damaging (even if only slightly). There's no real advantage in having the document colour space match the display colour space.

If you're eventually making an image for web then save the original. make a copy, convert to sRGB + embed the profile 

I hope this helps
neil barstow, colourmanagement net - adobe forum volunteer - co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management

[lwmsmd]

Thanks. I'm primarily interested in best way to match monitor image to what comes out of the printer. I'll find your articles referenced above and dive in. 

[Conrad_C]

When using this display and color space above, is it best to convert a photo taken in the Adobe RGB 1998 space to an image with the profile "Image P3" to match the gamut of the monitor? Or is it best to leave the photo in Adobe RGB and expect to have some "clipping of colors?"

By @lwmsmd

If your largest concern is printing, your reference is the print, not the display, so there is no need to convert the file to serve the display. Edit it as best as you can within the display’s color gamut, and then when you print it will be subject to the limitations of the ink + paper color gamut.

Although you can be concerned with clipping, keep this perspective in mind: Although a P3 display might not cover all of the same colors as Adobe RGB, both P3 and Adobe RGB cover a much larger gamut than the roughly sRGB displays that professionals edited print jobs on for decades. So a P3 display is still a huge improvement over the past.

I have read that the profile P3-65 represents about 85% of the colors available in Adobe RGB. This appears to especially confusing when I try to print an image.

By @lwmsmd

An important thing to remember is that percentage comparisons of color gamuts are not very useful. The reason is that the 3D shape of real world color gamuts is not uniform, not a perfect sphere or cube. Their shapes are highly irregular. One misinterpretation from reading that percentage is to conclude that P3 covers fewer colors. But that is not true, or at least it’s incomplete, because it goes both ways. The irregular shapes mean that it is also true that Adobe RGB covers less than 90% of colors in P3. 

In the 3D comparison below, you see that neither gamut fully covers the other, so what they really do is cover different similar gamuts. P3 D65 is shown in gray, so you can see that over some colors it falls short of Adobe RGB, but in other colors P3 D65 extends further than Adobe RGB. So actually, neither is fully superior to the other…both are great wide gamuts.

Another major problem with a percentage comparison is that it doesn’t tell you which colors are missing in the percentage they don’t have in common. How much do those missing colors matter? Are they mostly purples, but your images don’t use purple so the difference doesn’t matter? Or does the color difference affect colors in your landscapes or product photos, so it does matter?

Also, a percentage comparison tells you nothing about how well the display color gamut covers matches up with the gamut of the ink and paper combination you will use. What you see below, left to right are: First, a common CMYK print gamut (Coated FOGRA39), then how much that print gamut is covered by P3 D65, then by how much that’s covered by Adobe RGB. What you see is that both P3 D65 and Adobe RGB cover almost all of that Coated FOGRA39 print gamut, and both can’t reproduce a small portion of Coated FOGRA39 extreme blues/greens (the little bit shown in gray). What you don’t see is that if these were rotated, on the other side both P3 and Adobe RGB can reproduce all of the warm colors in Coated FOGRA39. 

In general, what this tells you is that Adobe RGB can reproduce slightly more print colors than P3. But whether that difference is important depends on what colors are in your images, and what printing conditions you need to target. For example, this comparison has different results when compared to uncoated FOGRA39, and different again when compared to the color gamut of my inkjet printer.

Most of the time you’ll find P3 D65 is just as good as Adobe RGB, and depending on the colors in the image and the print color gamut, maybe sometimes better.

[lwmsmd]

Thanks, this is really helpful, along with the other reply posts here for this thread. Can I assume then, that going through the View> Proof Set Up > Custom > Device to simulate (with choice of the ICC profile associated with your paper choice) is the best way to preview how the image will appear in print, realizing that there may be some surprises based on the limitations of the monitor and the paper.

[Conrad_C]

Can I assume then, that going through the View> Proof Set Up > Custom > Device to simulate (with choice of the ICC profile associated with your paper choice) is the best way to preview how the image will appear in print, realizing that there may be some surprises based on the limitations of the monitor and the paper.

By @lwmsmd

Yes, that’s correct, and it’s a realistic attitude. You’ve got a high quality wide gamut display, so soft-proofing should be more accurate than on most displays.

On the Apple XDR displays, the Reference Mode preset you select controls how the display reproduces color; for print, some good choices are Photography (P3-D65) (which sounds like what you’ve selected) and Design & Print (P3-D50), depending on the proofing standard your printing company follows. The only difference between those two Reference Mode presets is the white point (D65 vs. D50). If you customize a copy of either preset, typically the only thing to change might be lowering the luminance from the default of 160 nits.

If soft-proofing is set up properly, now you have the best available (though not perfect) simulation of what the colors will look like in print, and you can edit while Proof Colors is on.

[lwmsmd]

Humble thanks, again.

Laura Williams
Sent from my iPhone

[TheDigitalDog]

Actually Adobe RGB and P3 have the same number of colors. As would sRGB and ProPhoto RGB. They have a differnt range of colors (not numbers). That's based upon encoding. 

Color Numbers and Color Gamut.
Does Adobe RGB (1998) have more colors than sRGB? It’s the wrong question but no it doesn't. But to uncover why, we have to look at a few facts about color spaces, specifically RGB working spaces like sRGB, Adobe RGB (1998), ProPhoto RGB.
Adobe RGB (1998) and sRGB, ProPhoto RGB are just color spaces, containers. They don't inherently have any information other than specifications for primaries, white point, and gamma. Until we actually have a pixel, they don’t contain any information. The pixel has what is called an encoding which can provide a number of possible device values. For example, 24 bit color, (three channels, 8-bit each) can mathematically define 16.7 million device values. Can we see 16.7 million colors? No. Far less. Depending on who’s figures you examine, the range is said to be “more than 100,000 to 10 million”. The number is up to debate but the point is, we can use math to produce a value that has no actual relationship to what we can see. All the RGB working spaces have exactly the same number of addressable device values and the total number is set by the bit depth of the image file used for encoding, i.e., 8-bit, 16-bit.
Before we can define a number of colors, we have to define: What is color? Color isn’t a wavelength or property of light. Color, is a perceptual property, something that occurs deep inside our brains. So if you can't see it, it's not a color. As such, colors are defined based on perceptual experiments. Color is not a particular wavelength of light, It is a cognitive perception. Another term is Color Value, which refer to human perception and specifically to colorimetry. Lab, Luv, XYZ, Yxy, etc are all color values. We can use math and a metric called deltaE to define when one set of color values which are imperceptible (indistinguishable) from another set of numbers (color values). delta-E refers to differences in color values. For sake of argument, let’s say in one color space, sRGB, it isn’t possible to see a difference between 2/255/240 and 1/255/240 as they have the same Lab values (90/-54/-8). As such, we can’t count that example as being two colors, we can’t see any difference between them, they look identical. A deltaE of less than 1 between two color values is said to be imperceptible but to complicate matters, there are several formulas for calculating this metric. Further the ability of the eye distinguish two colors as different and is more limited for yellows but is better for greens and blues. This just adds even more difficulty in assigning a meaningful and accurate number of colors to these colors spaces.
Now we have to look at color spaces like ProPhoto RGB. If you examine a plot of this synthetic color space on top of the gamut of human vision (the CIE chromaticity diagram), part of it falls outside the plot. It can define device values, numbers, which represent “colors" we can’t see. So these “imagery colors” can’t be counted when we ask, does ProPhoto RGB have more colors than sRGB or another color space. One of the best explanations of why it is folly to even attempt to put a number (of colors) on top of a color space comes from Graeme Gill the creator of the Argyll Color Management System: "Colorspaces are conceptually continuous, not discrete, therefore it's wrong to talk about number of colors". Just examining ProPhoto RGB further illustrates it is impossible to define the number of colors it can contain as it can defines color values that we can’t see as colors. Parts of ProPhoto RGB’s gamut lies outside human vision!

Much like 24 bit color can define more device values than colors we can see. Encoding is however a useful attribute when editing our images so the point isn’t to dismiss it but rather point out, it provides values for something that isn’t a color, it’s just a number, a device value. As an analogy, if you were to purchase a ruler to measure something, it is possible the tiny lines that divide up the unit of measure could be finer than you can see. What would be the point of giving you a 1 foot long ruler where the individual lines that defined the distance between each was a micron apart instead of a 1/16 of an inch? The micron unit is valid. You just can’t see it or use it with your naked eye to measure anything. Think of the encoding of a pixel value the same way with respect to color expect unlike a micron that does exist, a device value defining a color you can’t see doesn’t exist; it’s not a color.

The difference in color gamuts is their range and the scale of colors, not the number of colors values. This confuses many people because they see a larger gamut plot, a larger volume, and assume larger means more colors. But one has nothing to do with the other. ProPhoto RGB covers a larger range of chroma (what some call Saturation) than Adobe RGB (1998). Adobe RGB (1998) covers a larger range of chroma than sRGB. This has nothing to do with the number of device values, that’s an attribute of how we encode the pixel values. And we can use finer ways to divide up this data. For example, in "16-bit color", the math allows us to define billion’s of color values, but that doesn’t change the fact we still can’t see 16.7 million colors in the 24 bit encoding of these pixels. As such, it’s best to talk about encoding having a potential to define millions or billions of numbers, device values, that could be associated to a color value thus color, if we could see them. But if we can’t differentiae them visibly, it is silly to suggest they are indeed colors. Don’t confuse a color number, a device value, for a color, a color you can see!

Color numbers may not be Color!
In sRGB, two pixels with different RGB device values have the same Lab values. They ARE the same color! This is how we can define 16.7 million device color values but not 16.7 million actual visisble colors: We can't see that many colors.
See illustration: http://digitaldog.net/files/ColorNumbersNotColors.jpg

Epilogue: Why ProPhoto RGB
A larger color space will have a greater distance between two neighboring encoding values (R255/B0/G0 and R254/B0/G0 as an example). The deltaE (distance/difference) is greater in wider gamut spaces. But with high bit data (what Photoshop calls "16-bit"), there is no issue when editing numbers with a colorimetric wider distance.
While it is true that the wider the gamut of a color space, and thus the wider granularity in a color space, the harder it is to handle subtle colors. This is why wide gamut displays that can't revert to sRGB are not ideal for all work (ideally you need two units). There are way, way more colors that can be defined in something like ProPhoto RGB than you could possibly output, true. But we have to live with a disconnect between the simple shapes of RGB working space and the vastly more complex shapes of output color spaces to the point we're trying to fit round pegs in square holes. To do this, you need a much larger square hole. 

Simple matrix profiles of RGB working spaces when plotted 3 dimensionally illustrate that they reach their maximum saturation at high luminance levels. The opposite is seen with print (output) color spaces. Printers produce color by adding ink or some colorant, while working space profiles are based on building more saturation by adding more light due to the differences in subtractive and additive color models. To counter this, you need a really big RGB working space like ProPhoto RGB again due to the simple size and to fit the round peg in the bigger square hole. RGB working spaces have shapes which are simple and predictable and differ greatly from output color spaces. Then there is the issue of very dark colors of intense saturation which do occur in nature and we can capture with many devices. Many of these colors fall outside Adobe RGB (1998) and when you encode into such a color space or smaller gamut, you clip the colors to the degree that smooth gradations become solid blobs in print, again due to the dissimilar shapes and differences in how the two spaces relate to luminance. So the advantage of ProPhoto isn't only about retaining all those out-of-gamut colors it's also about maintaining the dissimilarities between them, so that you can map them into a printable color space as gradations rather than ending up as blobs. 

Here is a link to a TIFF that I built to show the effect of the 'blobs' and lack of definition of dark but very saturated colors using sRGB (Red dots) versus the same image in ProPhoto RGB (Green dots). The image was synthetic, a Granger Rainbow which contains a huge number of possible colors. You can see that the gamut of ProPhoto is larger as expected. But notice the clumping of the colored red vs. green dots in darker tones which are lower down in the plot. Both RGB working space were converted to a final output printer color space (Epson 3880 Luster). 

http://www.digitaldog.net/files/sRGBvsPro3DPlot_Granger.tif