Confused with "Bits" 36-bit/48-bit?

[bd_noob09]

Hey guys, have a few question in regard to various color support - I'm a bit confused with the different ratings of TVs and Blu-ray players.

First, I have a Sony 37" BRAVIA XBR Series LCD Flat Panel HDTV that has a 10-bit display panel and processor. Okay.

I've heard some TVs have 12-bit and 16-bit display panels and processors. Okay.

I'm interested in purchasing one of the three upcoming Pioneer players: http://www.ubergizmo.com/15/archives...ay_player.html

The Pioneer BDP-120 will have HDMI 1.3a output with 36-bit deep color support. The Pioneer BDP-320 will have HDMI 1.3a output with 48-bit deep color support. WHAT?

Also, is there a difference between "deep color" and just normal color?

[4K2K]

Yes there is a difference between Deep Colour and normal colour.

All commercial Blu-ray discs are 8 bit per colour channel (the black-white levels are probably calibrated to values 16-235 so it might not even use the full 8 bit range).
3x8=24 bit total

Deep Colour - I think this is an option on some camcorders to give an extended colour range.

Some Blu-ray players attempt to convert 8 bit to higher bitrate colour, but it won't be true higher bitrate colour. It's sort of like upscaling. They try to smooth out colour graduations (eg. according to one insider, I think he said something like, if they see a value of 10 and on the next frame it's 11, and nothing has changed position, the actual value might be 10.5) so that might be what some Blu-ray players (ie. the most expensive ones) might use when trying convert an 8 bit colour value into a 10 or 12 bit one. But it won't be true 10 or 12 bit because Blu-ray doesn't support it.

[SkantDragon]

You're being caught out by different units there.

The 12 and 16 bit ones are referring to the number of bits per color.
The 36 and 48 bit ones are referring to total number of bits per pixel.

12 bits per color channel * 3 colors (red, green, and blue) = 36 bits per pixel.
16 bits per color channel * 3 colors (red, green, and blue) = 48 bits per pixel.

So you're actually looking at the same bit depths... they're just listed in two different ways.


Soemthing to keep in mind... the human eye can't distinguish more than 8 bit color. And no video sources (including Blu-ray) transmit more than 8 bit color. And it's unlikely any ever will.

[bd_noob09]

Originally Posted by SkantDragon

Soemthing to keep in mind... the human eye can't distinguish more than 8 bit color. And no video sources (including Blu-ray) transmit more than 8 bit color. And it's unlikely any ever will.

Interesting. If this is true, 8bits x 3 colors = 24bits per pixel.

They why do these particular Pioneer players: http://www.ubergizmo.com/15/archives...ay_player.html support 36-bit deep color and 48-bit deep color, respectively?

Does that simply mean these particular players have the ability to support 36-bit/48-bit color, ONLY IF someone actually develops Blu-rays that utilize 36-bit, 48-bit, etc??

So basically, right now, all Blu-rays discs are 24-bit. So 36-bit/48-bit is only marketing hype??

[Bobby Henderson]

Perhaps at some point in the future we'll start seeing Deep Color enhanced Blu-ray discs. Currently not many HDTV sets can properly support the enhanced color gamut range, so it's basically not worth it to movie studios right now to significantly increase movie file sizes with deep color levels just for the benefit of a small number of viewers.

Taking a movie from 8-bit RGB color channels to 12-bit RGB channels would increase the movie file size by 150%. Going to 16-bit would double the movie's file size.

Maybe some time in the future when even better quality HDTV video displays (RGB LED backlit, OLED, etc.) are common then deep color will probably be worth considering.

Another issue to consider is the current "fashion" in Hollywood cinematography of draining a great deal of color out of the image to make it look harsh and grungy. Or they put strange washes of green or brown over everything. A movie like Speed Racer probably could have shown off Deep Color techniques really well. But it would take a lot more than the space on a BD-25 to get the job done.

[SkantDragon]

Originally Posted by bd_noob09

Does that simply mean these particular players have the ability to support 36-bit/48-bit color, ONLY IF someone actually develops Blu-rays that utilize 36-bit, 48-bit, etc??

So basically, right now, all Blu-rays discs are 24-bit. So 36-bit/48-bit is only marketing hype??

That is essentually correct. Blu-ray does not even include greater than 24 bit color in its specification. And it is unlikely that you will ever see any media or broadcast service ever go beyond 8 bits per channel.

This isn't like the discussions about resolutions or video bit rates where people argue about whether and how much difference it makes. 8 bits per channel is already well beyond the human eye's ability to distinguish at all. Period.

However... there is a wrinkle to consider.

In order to still have 8 real bits per color channel when you're done, video processing needs to be done at more than 8 bits because of the effect of compounding errors.

To explain, lets think of dollars and cents. Lets say you have an equation:

( X / 2 + Y / 3 + Z / 4) * 10
X=$7
Y=$10
Z=$25

Now lets look at it using whole dollars only:

$7 / 2 = $4
$10 / 3 = $3
$25 / 4 = $6

$4 + $3 + $6 = $13
$13 * 10 = $130

Now lets see what answer we get when we use cents:

$7 / 2 = $4.50
$10 / 3 = $3.33
$25 / 4 = $6.25

$4.50 + $3.33 + $6.25 = $14.08
$14.08 * 10 = $140.08

So the answer is $130 or $140 depending on whether you used the precision of cents in your math. The first answer is inaccurate by $10.08 cents (7.7%). The second answer is accurate to the nearest dollar.

That's what happens with these video processors. They'll use 12 or 16 bit math while they're doing their calculations, and then hack off the extra bits of precision down to 8 bits and display that. If all the math is done in 8 bits, the final result is actually less accurate than 8 bits.

So what does all this mean? It means that 12 and 16 bit color is very useful for editting formats (like those used in a studio during production), but not end user formats (like Blu-ray). And it can also be useful during interrim video processing, but not at the final result.

I hope that helps.

[Anthony P]

Does that simply mean these particular players have the ability to support 36-bit/48-bit color, ONLY IF someone actually develops Blu-rays that utilize 36-bit, 48-bit, etc??

the answer might bew yes or might be no. Sometimes it is like upscaling, the device (TV or player)uses surrounding pixels and where they fall on the colour chart to determin what the more "detailed" colour should be.

[Clark Kent]

Originally Posted by bd_noob09

Does that simply mean these particular players have the ability to support 36-bit/48-bit color, ONLY IF someone actually develops Blu-rays that utilize 36-bit, 48-bit, etc??

So basically, right now, all Blu-rays discs are 24-bit. So 36-bit/48-bit is only marketing hype??

Yes for traditional movie and video content. There has been some talk that videogames might start using higher bit depths in the next couple of years.