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

[MacRumors]

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.

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.

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

 

[keysofanxiety]

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.

 

[wordup60]

You've made 11 billion dollars profit in 3 months

On iPhones, not Macs.

 

[kd5jos]

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?

 

[MrGimper]

Am I being a bit slow here.....? On 10.11.1 GM my 2014 retina iMac shows 30-bit pixel depth, however on 10.11.2 b1 my 2014 retina Macbook Pro shows 32-bit pixel depth. So is my rMBP better in this respect?

 

[norrismantooth]

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.

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.

 

[shareef777]

On iPhones, not Macs.

Quite a bit of people have these Macs because of the phones (or vice versa). It's their ecosystem that sells most of their products and having a weak link (which a 5400rpm drive certainly is in any system) doesn't bode well for the overall system.

 

[keysofanxiety]

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.

 

[SaxPlayer]

Presumably for people like me who have a 10-bit monitor (in my case an LG 31MU97 4K) this will be good news when I decide to update from Yosemite. It will be interesting to see if I notice the difference.

 

[Pike R. Alpha]

Am I being a bit slow here.....? On 10.11.1 GM my 2014 retina iMac shows 30-bit pixel depth, however on 10.11.2 b1 my 2014 retina Macbook Pro shows 32-bit pixel depth. So is my rMBP better in this respect?

No. What you have is ARGB8888 – 8 bits for alpha and 8 for colors. Not ARGB2101010 – which is 2 bits for alpha and 10 bits for colors.

 

[dasmb]

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.

 

[Rocketman]

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.

 

[Jon the Heretic]

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?

It is a curious thing to be sure but our displays need to process far more colors than any of us can discriminate. The color bands are evidence more colors are needed regardless of our own limitations.

I have always thought that through better programming we could eliminate the banding we see on our 24-bit displays and TVs, the way we use to dither 8-bit GIFs on 256 color displays an eon ago. But our direct color displays of the modern era must not be quite good enough at dithering as they should be. Short of coming up with another approach to direct color (coupled with better dithering...so no longer use true direct color but a smart hybrid of the technologies), 30-bit displays may be the answer to eliminate the ugly bands we see everywhere today.

 

[coolfactor]

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.

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

 

[redscull]

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.

 

[keysofanxiety]

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.

 

[dannys1]

People moaning about 5400rpm drives are really boring. Its not like its the only choice, then it would be worth moaning about. 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. Who cares if they offer 1000rpm drives? Buy the model you want and consider THAT the base entry price and if you think thats too expensive moan about that, not that the model you can afford doesn't carry the specs you want. Apple stuff is expensive, we've known this for decades.

Also these 5400rpm drives are only in the the 21" iMac. I really wouldn't like to know the heat a 7200rpm 3.5" drive would kick out in those things, you'd have to cripple one anyway at which case you'd be better off running a 5400 WD Green. The perceivable difference between the two these days is negligible, its not like it would be running a WD Black 7200 even if there was one. I wouldn't run a system without forking out for an SSD now days anyway, which is available.

 

[Jon the Heretic]

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

Nice analysis. Another way to put it is that we wouldn't need as many colors if our displays were optimized to display the RIGHT colors -- those that the human eye is most attuned to. Because of individual differences in absorption in the cones for different people, you may actually need to support more than just those 7-bit 'human colors' so that the displays look right across different people. Variation is fundamental to any biological system. And as you point out, hue is not the only important attribute but brightness and saturation too.

Short of that, we could just go brute force -- show more and more colors on displays, until we completely blanket the human 7-bit color spectrum with all of the colors that humans are capable of perceiving. That seems to be the direction technology is going, and just maybe it is easier than creating a more limited display that carefully mirrors the capability of the human retina in a one to one fashion.

 

[SlipperySlop]

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.

Stop it already with this nonsense. SSD's are still expensive and not everyone wants to pay for it and those who want to keep the prices down will be fine with the 5400 drive. If you don't like it, don't buy it.

 

[redscull]

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.

 

[Peace]

There's nothing new here. My 3 year old Thunderbolt Display does 30-bit also.

 

[termite]

The average human eye registers... 7 bits of color.

That is entirely false.

Keep in mind however that the human eye has different sensitivities to different colors. The eye can distinguish far more shades of green than shades of blue. It's trivially easy to create a deep-color image where green varies slightly from left to right. Sampled at 8-bits, there will be tremendous vertical banding where your eye notices each single-bit step. Sampled at 10-bits looks much better.

 

[ThunderSkunk]

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.

They won't do it until the price of SSDs comes down, but the #1 thing that'll make the price of SSDs come down is Apple ordering hundreds of millions of units and companies increasing production to meet that greater demand. Of course they'll want a generous commitment from Apple in advance to fund the inherent costs involved. It's a waiting game, to see which side gets desperate enough to spend the $ to do it. A waiting game that's gone on far too long.

 

[macduke]

This is REALLY tempting me to get a 5K iMac. Must…resist…

 

[KALLT]

There's nothing new here. My 3 year old Thunderbolt Display does 30-bit also.

View attachment 596949

The display does, but that doesn't say anything about the graphics card, drivers and OS support.

You can test this by downloading the ZIP file on the bottom of this webpage, unzip it and open the PSD file in Preview. If the gradient is smooth, it's 10 bit, if you see stripes then it's not.