4K and 5K iMacs Support 10-Bit Color Depth on OS X El Capitan

Apple's latest 4K and 5K iMacs support a 10-bit graphics driver on OS X El Capitan, allowing for smoother color transitions, according to German website Mac & i. The 10-bit color output enables 1024 gradations per color channel, a significant increase from 256 with 8-bit depth on previous iMacs.

iMac-10-bit
30 bit pixel depth — 10 bit for each RGB color (Image: cinema5D)

Digital filmmaking news website cinema5D explains the technical benefits of 10-bit color depth for professional colorists, photographers and editors:
Professionals know that 10-bit screen color is the desired color depth for serious color correction. When you work in 8-bit you often see banding artefacts and lose detail on soft gradients which makes editing harder and less accurate.

This is not to be confused with the bit depth of your source files. We all know that working with video DSLRs or other heavily compressed video footage that is limited to 8 bit color depth gives you less options during grading and 10 bit, 12 bit or even 16 bit color photos and videos are better. On the screen side 10 bit is the desired depth to let you view the end result without gradation steps.
The new 10-bit color depth reportedly only works within the Preview and Photos applications for now, but other third-party software should eventually take advantage of the technology. The 2014 5K iMac also supports 10-bit color depth on OS X El Capitan, according to these reports.

Related Roundups: iMac, OS X El Capitan
Buyer's Guide: iMac (Don't Buy)


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11 months ago
Why Apple go to all this trouble with amazing technology and then cripple it by shoving in a 5400RPM drive is beyond me. You've made 11 billion dollars profit in 3 months. Just make SSDs standard in all your computers already.
Rating: 44 Votes
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11 months ago

The average human eye registers... 7 bits of color. By using ten bit color you go from one bit of color you can't see to three bits of color you can't see (per channel, per pixel). So I am asking my graphics processor to process 9 bits per pixel that make no discernible difference in the quality of the image. Why not leave it at 8 bits and maybe OpenCl can make use of the unused graphics card clock cycles/processing?


Well, given that we can ALL see gradation issues with 8 bit, they must be on to something right?

The secret is that reproduction of light intensity by pixels, as well as the capturing of light intensity by photosensors, is linear. Half the value, half as much light.

The eye, on the other hand, does not process light information linearly. We tend to be able to pick out detail in medium dark areas better than those in very dark or very light areas.

As such, if you were to use 7 or 8 bit color, the eye can easily see incremental changes in color in the middle brightness band, whereas incremental changes in very bright parts of the band are nearly impossible to discern.

By increasing the bit level, you better cover this gap in the perceptual gamut of the eye. You could get the same value in 7 pixels by applying a mapping function equivalent to the eye's discrimination to the hardware pixels and to the light signal in memory.

However, you'd find this used a LOT more resources and was incorrect far more often than simply pushing some extra bits. That's because mapping is computationally expensive, every eye is different and it's unlikely a mapping function on commodity hardware and in commodity software is going to meet your exact need.
Rating: 20 Votes
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11 months ago

I don't think anybody I know should buy the base model.

Correction: Nobody should buy the base model. And they shouldn't even sell it because that dupes unwitting customers. Any version with a 5400 disk is truly a crappy computer. That disk is a bottleneck that cripples an otherwise excellent machine. Whatever dollars you save buying that version, they aren't worth it. The dollars you're still spending are being spent on junk at that point.

It seems like every iMac discussion going forward, no matter what cool feature it is they added, is going to quickly diverge into complaints about how crappy the disk is and how that completely overshadows anything else they do.
Rating: 17 Votes
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11 months ago

And SSDs do not yet have the same capacities. Just attach an external SSD and be happy already, eh? :)


If the fix to the performance problems on a £1500 iMac is to run the OS through an external drive — well, I think that gives a stronger argument than I can ever articulate.
Rating: 16 Votes
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11 months ago

Apple invested in the supply chain in astronomical numbers. Until the stock of the 5400RPM drives are gone, and the cost of a sizable SSD comes down, and Apple can corner that part of the market for their own longevity/sustaining, we won't see it. 2 years ago, I paid ~$370 for a 480GB SSD. I've never worried about running out of space.


Yep, I know the feeling. 4 years ago I paid £240 for an OCZ 240GB SSD that had read/write speeds of 150MB/s either way. I buggered it after I stupidly enabled TRIM. Luckily they later replaced for a 256GB.

Now I can buy a 500GB Samsung 850 EVO SSD for less than £120. Apple could easily get that far cheaper, that's not in question.

5400RPMs in 2015, with those specs, and at that price, is a joke. You can't even swap it out for an SSD. No appreciation of longevity, or value for money. Raise the price by £100 if you have to, and throw in a 256GB PCI-e SSD on the base model. Just don't offer 5400RPM drives for Christ's sake.
Rating: 15 Votes
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11 months ago

What you're actually complaining about is that you think its too expensive to buy the drive you want and you expect it for less.

No. That's not it at all. The point is that the Apple brand is associated with a certain amount of quality and prestige. They refused to jump on the netbook bandwagon way back when because netbooks, whether $200 or $2, were garbage. At any price, the user experience was so terrible that it would be cruel to subject a person to them. Apple recognized this and held themselves to a higher standard.

They no longer hold themselves to that higher standard. They are now selling a computer which truly is garbage. Their 5400 disk iMacs are so frustrating to use that the experience damages their brand and reputation. And non-tech consumers just don't know enough to avoid this trap. They'll buy the base model because it's cheapest or simply in stock, and assume that no matter what, they can rely on Apple to give them a solid product. That's what Apple is known for, after all. But they will feel swindled as soon as they start using it. It offers a horrible user experience right out of the box.

As an Apple fan and shareholder, I do not like where this is headed. I don't think it's in the best interest of Apple to degrade its reputation by sacrificing the quality of their products. I want them to keep being awesome, not become yet another computer maker willing to sell whatever cheap drivel they can.
Rating: 15 Votes
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11 months ago

And SSDs do not yet have the same capacities. Just attach an external SSD and be happy already, eh? :)

Do you know what the product category is called the iMac falls into?

ALL in one. Not SOME in one. It's ALL in one, meaning all the essentials for meaningful, reasonable operation come in one device + keyboard and mouse combination.

I'm surprised to which great lengths the Apple defense force is going these days, basically completely ignoring the principles Apple once stood for almost exclusively in the market. These days they are leaving many of those behind.


I have to wonder what all these defenders, not necessarily you here, actually still defend Apple for if more and more core values of Apple are being taken away, more and more magic is lost to cost reduction, "clever" up-selling and held back features (don't anyone dare deny this fact, it's well beyond obvious by now, no sweet word by Tim will change my mind).
Are they defending the brand, or the brand they once came to "fall in love" with?

I doubt it's the latter.

But us Apple customers are a special breed. We'll yell and yell loudly and continue to pony up the dough for increasingly less fitting products, until something collapses and they might find their way back to more honest offerings (from an educated buyer's perspective)

Glassed Silver:mac
Rating: 14 Votes
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11 months ago

Why Apple go to all this trouble with amazing technology and then cripple it by shoving in a 5400RPM drive is beyond me. You've made 11 billion dollars profit in 3 months. Just make SSDs standard in all your computers already.

If you opt to go for the non-fusion drive, that choice is yours. If you want better performance you must pay for it. If you are a low power user maybe the $100 savings is all you actually care about.

It is a choice. Apple is not forcing anything on you despite all the "likes" your post has received. It is marketing driving it. They have a "low base price". That's it. That's all. I don't think anybody I know should buy the base model.
Rating: 9 Votes
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11 months ago

Why Apple go to all this trouble with amazing technology and then cripple it by shoving in a 5400RPM drive is beyond me. You've made 11 billion dollars profit in 3 months. Just make SSDs standard in all your computers already.


Amen to that. Apple usually moves the industry forward. But this decision reflects poorly on them. This and the infamous 16GB iOS devices. They should do away with both.
Rating: 7 Votes
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11 months ago

You've made 11 billion dollars profit in 3 months


On iPhones, not Macs.
Rating: 7 Votes
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