New iMacs were released recently (13th Oct, 2015). The iMac is now a compelling machine in both 21.v-inch and 27-inch formats. The upgrade includes a new panel that has an extended color gamut.
Producing and Comparing Gamuts
Normal white LED backlights produce a lot of blueish light, but non as much ruddy or green light. Late 2015 iMacs are using the not-that-new GB-r LED backlight technology. This creates a much stronger green and reddish spectral component to match the already strong blueish. The larger gamut can reproduce more brilliant greens, reds, and their derivatives (cyan, yellow, magenta). These panels can target larger colorspaces, the about common being Adobe RGB in professional displays. In contempo memory Apple tree has never shipped a wide gamut display, I am happy to see that has changed. Hopefully the larger gamut will discover its way to all Apple products eventually.
Apple decided to go with DCI-P3 instead of Adobe RGB for their wide gamut colorspace. This is an interesting conclusion, lets try to empathise the differences. When we take a second chromaticity diagram of both and compare them we go
figure 1. Apple’s target P3 colorspace tin encompass fewer teals and greens (light shaded area). However, P3 is stronger in yellow-green, yellowish, orangish, scarlet, and magenta (dark shaded surface area). If instead we compare P3 to the standard sRGB colorspace, the differences are even more than significant
( figure 2 ).
Real Earth Comparison — The Teal Lake
I selected a series of test images to analyze the difference in real usage. Using soft proofing in Lightroom against a DCI-P3 target, images were selected which exceed sRGB but which P3 could reproduce. A pair of files was exported for each image, one in ProPhoto RGB, and the other converted to sRGB. And then I visited an Apple Store and annoyed the staff (sorry!). I did bring my calibration tool with software, but they did not allow me use information technology to contour the display. It is very hard to photograph a screen and have the subtle color differences show upward. Most of my illustration here will exist generated overlays.
Showtime off is this lovely photo of a lake in Canada. The teals in this photograph represent a example where Adobe RGB surpasses P3, and both colorspaces are markedly larger than sRGB. The composite overlay
( figure 4 )
indicates which areas of the image are non reproducible past which colorspaces. Cherry-red is not reproducible by sRGB, blue not reproducible by sRGB or Apple tree P3, and green is not reproducible by sRGB, Apple P3, or Adobe RGB. Each colorspace in plow has amend coverage of teal hues, and therefore can reproduce more than of the image.
The scarlet overlay correlates to sRGB. At the lesser left is a 3D plot representing sRGB in color and Adobe RGB in white. The red shaded area indicates the colorspace coverage sRGB is missing to display these teal colors. The overlays on the master image and on the 3D plots chronicle to roughly the same colors, simply a different visual representation. 3D LAB profiles will exist discussed briefly afterward.
Real Earth Comparison — The Orange Car
I similar orange cars, and so does the P3 colorspace. Orange is i of the areas where P3 exceeds both Adobe RGB and sRGB. In this composite overlay
( figure vi )
sRGB cannot reproduce whatsoever of the orange paint whereas P3 can become pretty much all of it. Note that if y’all are viewing this page on an extended gamut display
figure iii, five, and 12
have been reproduced in extended colorspace. You lot tin can download and view these if your browser does not support extended colorspaces.
In the 3D plots information technology is clear that the gamut required to display the brilliant, rich orange is only available in the P3 colorspace. On the 27-inch iMac in person this photo had a lot of punch. The orangish was brilliant, saturated, and vivid to look at
( effigy 7 ).
Methods of Comparing Gamuts
When yous nautical chart sRGB against Adobe RGB on a 2d chromaticity diagram
( figure eight ), the treatment of orange looks well-nigh identical. Why does Adobe RGB practise significantly better than sRGB when reproducing the orange machine? While the 2nd diagram is a useful way of comparison gamuts, it is not the just way, and mayhap non the best manner either. Enter the 3D plot view, where the visualization takes into account not only colour only luminance likewise. Nosotros can run across in
effigy nine, 10
that Adobe RGB supports better vivid oranges, reds, and magentas than sRGB. It also has an advantage in bright yellows, yellow greens, and dark greens. All this in addition to its very clearly stronger bright teal and green. Adobe RGB is an even larger comeback over sRGB than it initially seems.
If y’all run Os X you can view these 3D profiles easily. In
there is an application called ColorSync Utility. Information technology allows you to select profiles from the left pane and view them
( figure 11 ). I take captured a video of tumbling around an sRGB vs Adobe RGB comparing in ColorSync Utility. It is available here (MP4, 2.4 MB): Video
Real Earth Comparing — The Greenish Bird
This is an interesting state of affairs because P3 and Adobe RGB excel at different shades of greenish in the aforementioned photo. Apple P3 does a good job rendering the yellow greens of the background establish. However, information technology tin non represent the more pure and darker greens on the parrot. Adobe RGB has the reverse trouble, doing a bang-up chore on the parrot but missing somewhat on the institute. sRGB is of course outclassed by both.
How I Learned to Stop Worrying and Love Wide Gamut
Extended gamut displays can help you enjoy richer photos. Prepare photos for print, or during the processing stages of any imaging pipeline. It could be useful to color form video which is destined for digital cinema. I’thou not sure how many people are doing that on iMacs, merely perhaps you could now. What Apple ships with the iMac is an exceptional display by whatsoever standard.
The deviation between sRGB and Apple tree P3 is noticeable, but not immense. I had to pick and choose carefully to find images which accentuate the differences. About of my photos prove no reward or only minor reward for extended colorspaces. People probably won’t notice a dramatic change and a majority of images will still be in sRGB. While the iPhone 6S shoots sRGB JPEGs, expect future phones to do better. Apple tree will most certainly follow the iMacs and nine.7-inch iPad Pro with more wide gamut devices.
OS X, and iOS too as of 9.3, offers fairly robust handling of color profiles. It gets almost things right near of the fourth dimension, and most content is color managed by default. A notable exception is OpenGL views. The most important thing to remember is that sRGB is the worldwide interchange colorspace. If you lot’re going to send images to somebody check if they are sRGB — if they are non, convert them. Preview tin can tell y’all what profile is assigned and ColorSync Utility can catechumen. This is a great resources to empathise Apple tree’s ColorSync implementation.
We tin only speculate why Apple tree decided to pick P3 every bit their wide gamut target. My personal theory is that it is a balanced enhancement of sRGB
( effigy 14 ). All hues except bluish receive a similar and notable extension. It was probably non done specifically to please professional printers or video colorists. As this feature continues to propagate, a lot of people volition get to enjoy more than brilliant images. That seems to be why Apple makes these improvements that are non strictly necessary. Democratization of technologies that amend the user experience.
The 27-inch 5K iMac has a model identifier of
iMac17,1. While the 21.5-inch 4K iMac’due south model identifier is
These iMacs are running specific new-product builds of Mac Os 10.xi.0 which will presumably exist rolled into x.eleven.1. The standard version of 10.11.0 is build 15A284. The 27-inch 5K iMac is running build 15A4310 and the 21.v-inch 4K iMac is running build 15A2301.
I have confirmed that 30-Fleck color is working on a 27-inch iMac. A 16-Bit greyscale ramp was used to test. Applications which support this capability are quite sparse. At the time of my testing Preview worked and Pixelmator did non. It is likely that applications need to opt‑in to utilise this characteristic. The standard 24-Chip pipeline is indicated with
Pixel Depth: 32-Bit Color (ARGB8888). New 30-Bit color pipelines will prove
Pixel Depth: thirty-Fleck Color (ARGB2101010)
Pixel Depth: CGSThirtyBitColor. I accept also been able to get 30-Bit color working on my Dell U2713H via DisplayPort. Support seemed thin and intermittent in earlier versions, only as of
everything works well in my feel.
iFixit reports the 21.5-inch 4K iMac uses LG’s LM215UH1 panel in this teardown. There does not seem to be much information on the panel available as of this writing.
Apple tree’south P3 gamut target appears to exist a lilliputian bit unlike than the one you get if you lot generate a contour using DCI’s specified coordinates. AnandTech revealed that Apple’southward P3 profile uses two.two gamma, whereas DCI’s spec calls for a gamma of 2.vi. I’ve used Apple tree’south target for all of my comparisons in this post. Both Apple’southward P3 profile and the generated one are available for download below.
The 27-inch 5K iMac with Intel i5-6500 and AMD Radeon R9 M390 has an Unigine Heaven Benchmark 4.0 score of 2008 using the Basic preset. Criterion output.
Subjectively these are both lovely displays. Contrast is high, accuracy out of the box seems quite decent, and the ones I saw wait to be hitting their P3 gamut targets. They get vivid only seem to retain contrast as you lot dim them — an important gene.
Here are some profiles I referenced during my research.
- The common Brandish P3 profile on all three of the wide gamut iMacs I tested (ZIP, 498 Bytes): Download
- 27-inch iMac 5K factory profile (ZIP, iii KB): Download
- 21.5-inch iMac 4K factory profile (Zippo, 3 KB): Download
- DCI-P3 profile generated in Photoshop from DCI-specified 10,y coordinates (ZIP, 757 Bytes): Download
These are dumps of
which may be useful for taking a deeper wait.
- ioreg dump from 27-inch 5K iMac (Zippo: 184 KB): Download
- ioreg dump from 21.v-inch 4K iMac (Null, 111 KB): Download
Hither are ACPI tables extracted using a tool called MaciASL for a Linux driver developer.
- ACPI dump from 27-inch 5K iMac (ZIP: 63 KB): Download