No it does not support 30 bit color depth. Most consumer displays do not even come close to 30 bit color depth. No consumer 4k displays support. Zero. Nor is it common. Reason being each panel would require a more expensive panel system board, more expensive polorizor etc. higher PPI panel are great, but just because they are a higher PPI does not make them better. It is good for marketing purposes. That is about it. A higher sub-pixel count is more important. Not how many are in front of the panel, but beneath it.
Quite the contrary. Contrast, black level, color accuracy are more important than a higher ppi. High ppi is needed but if you have that without the other factors that make a great display than that higher ppi is a waste. This is not the case with the imac 5k retina display. It is a great display. Fantastic.
But it cant touch a professional panel. Nor is it meant to. It is a consumer product. Nor does it need 30 bit per color like a professional display. And 30 bit displays are not common, at all. 8 bit with FRC is not a 30 bit panel. Nor is it a 10 bit panel.
If it can do billions or trillions of colors without a asterick next to the specs than it is most likely a 10 bit panel. Millions of colors is not a 10 bit panel, it is 8 bit. If the panel says " billions of colors" but has a low color gamut, like 72 percent, that is a 8 bit panel with frc. Not a true 10 bit panel. A NEC professional panel can display 100 percent color gamut in any range. A HP dreamcolor display tests out at over 115 percent color gamut with being a true 10 bit panel with FRC to take it to 14 bit! These 4k panels in the 500 range cannot compare. None of them are true 10 bit panels. If they were they would not cost 500-800 dollars.
Most professional panels use higher sub-pixels to achieve a higher color depth than consumer panels. Most of the best panels are 10 bit + FRC and 30 bit per color. Have very powerful panel system boards to do calibrations on the fly in realtime. Self calibration is built into the panel. The polarizer is usually higher quality single pane to reduce loss of color depth and accuracy.
The 5k imac is great. Just bought one. But it cannot touch any of the professional displays i have at my business, nor was it meant to.
The bit-precision of the display determines how many steps of brightness are possible. A display which supports 6 bits per sub-pixel will provide 64 (26) steps from darkest to brightest; a display which supports 8 bits will provide 256 (28) steps. A display that supports 10 bits per sub-pixel would givie it 1024 (210) steps. The bit-precision is a result of the design of the electronics which control the liquid crystal cells in the panel.
Since there are three sub-pixels, the maximum number of colors that a pixel can present is 2n x 2n x 2n
where n is the bit-precision of a sub-pixel. Therefore, an 8-bit design gives
28 x 28 x 28 = 16.7 million colors.
A display, with a 10-bit design, gives a palette of 210 x 210 x 210 = 1.07 billion colors
By the way, while many people talk about an 8-bit panel or a 10-bit panel, its also common to refer to the total number of bits needed to define a red-green-blue pixel. Therefore, its valid (and preferred) to refer to a 10 bit displays panel as a 30-bit panel. 30 is 10 + 10 + 10, which takes account of the 10 bits for each sub-pixel.
Many consumer displays have low-cost 18-bit panels. Some high end consumer high ppi displays (such as the imac 5k and the dell 5k ) have 24-bit panels. No 8 bit plus frc do not count. But a high end professional display is one of a small number of displays with a true 30-bit panel. The higher the bit- precision of a display, the better able it is to represent colors accurately.
A 8 bit or 24-bit panel, which offers 16.7 million colors, would be good for most consumers needs. However, there are cases where 8-bits per sub-pixel is not enough. Consider a grayscale image. Gray (including white and black) is produced when the three sub- pixels (red, green, and blue) are equally bright.
This means that the values for the three sub-pixels are the same: 35/35/35, for example. With 8-bits per sub-pixel, gray can go from 0/0/0 (black) to 255/255/255 (white). Therefore, there are only 256 levels of gray possible. This can lead to banding, which is an effect that arises because the step between adjacent levels of gray is big enough for the eye to detect. It can be a problem in certain kinds of visualization, such as 3D rendering for automotive styling. With a 30-bit panel, there are 1024 levels of gray, and its almost impossible for the eye to detect the step between adjacent levels.
Also, there are cases where images can have greater bit-precision than 24 bits, especially where subtle detail is important. Examples are: satellite imagery for intelligence agencies, or medical imagery for, say, mammography for example, or color accuracy for tv or movie production.
You will not see pixar or dreamworks getting rid of their dreamcolor or NEC displays to get a new 5k imac anytime soon. The imac retina with the 5k display is the best "consumer" display on the market, hands down. But it is not a professional display nor is it meant to be.
