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Calibrating VT50 to RGB 444 Source

post #1 of 8
Thread Starter 
A couple of my sources only output RGB, so i set my ps3 to output RGB and set it to limited and calibrated the vt50. I did not have time to go back and test thr same patterns at ycbcr, but did notice brightness was two clicks different between an RGB input and ycbcr

As far as calibrsting to an RGB source, are there any particular issues to look for or expect on a ycbcr source? i know some signal generators only output RGB, so id assume if the display handles either ok, this would not be an issue.

i have the PS3 set to 1080p/60 and RGB Limited the VT50 hdmi setting is Auto. Auto and Standard show no change, but of course NonStandard washes the image out since that is 0-255 and Limited on the PS3 is of course 16-235
post #2 of 8
I have calibrated many VT50s, and I've switched back and forth between RGB and YCbCr 4:2:2 and 4:4:4 many times. I've never seen a difference unless 1080P Pure Direct is on, in which case RGB color decoding is messed up while YCbCr 4:4:4 remains correct.
post #3 of 8
Thread Starter 
thanks chad it looks real good watching Dish with a ycbcr source so i assumed they must be similar. I agree on pure direct. Using spears and munsil it seemed to be ok ON on ycbcr, but the RGB results were not as good, so i cut that setting off.
post #4 of 8
Is the signal going through a receiver or anything else before it gets to the TV?
post #5 of 8
Thread Starter 
PS3--Denon 3313(video conversion set to off)--VT50

Just recently, I put the Spears disc in an Oppo 103 and checked ycbcr 444 and RGB 444. I found that with ycbcr the pure direct mode did make a positive difference on two patterns, so I was using it. On RGB, it had some negative effect, so since calibrating using the PS3(1080p/60 and RGB) and Mascior's disc here, I cut 1080p pure direct off.

All this would be more simple if Sony did not treat apps as games, and output stuff like Amazon, Netflix and Vudu at RGB instead of what the PS3 is set at.
post #6 of 8
Just to speak to very specific points...

First... there is no such thing as RGB 4:4:4. You have RGB and you have YCbCr. RGB can be 0-255 or 16-235. YCbCr is output from disc players and other source components in either 4:2:2 or 4:4:4 which tell you how much color decimation was applied. 4:4:4 carries much more color information than humans can see. 4:2:2 would be perfectly fine for high-fidelity video if there were no other issues (like not using all 8-bits effectively). YCbCr is supposed to only exist in the 16-235 digital levels format.

If the video display is well-designed, there will be absolutely NO measurable or visible difference between RGB and YCbCr and it won't matter if the YCbCr is in 4:2:2 format or 4:4:4 format. All 3 formats should measure and appear identical. In the real world, there are displays that simply produce better looking images in either RGB or YCbCr mode -- check both modes, if you don't see any difference, there isn't any difference. It's typically not that difficult to notice so don't spend hours or weeks or months trying to decide if RGB or YCbCr looks better. If you can't tell there's a difference in 5 or 10 minutes, there's no difference worth worrying about.

Incedentally, if you convert RGB data directly to YCbCr without any color decimation, you get YCbCr 4:4:4 -- both color formats contain more data than human vision can make use of. Color decimation is the process of removing superfluous color information... done properly, YCbCr 4:2:2 is completely indistinguishable from 4:4:4 but 4:2:2 requires less bandwidth to transmit across cables or to store in memory (temporarily or permanently). Blu-ray discs are encoded in YCbCr 4:2:0. But 4:2:2 is output from disc players unless you change to RGB or YCbCr 4:4:4. 4:2:2 is the best all-around option unless you happen to own a display that simply looks better when displaying images received in RGB format. All that said... sometime, there's no 4:2:2 option... you can pick RGB or YCbCr 4:4:4 and that's all. Or in some cases RGB may be the only available option (our old DISH receiver was like that). Obviously, you can only work with the choices that are available to you.
post #7 of 8
Sorry to bring this thread back up but i have the same issues the op. I have a gt50 and it also has the 1080p pure direct mode, and every time i turn on my wii u or ps3 and enable the pure direct mode the color red in specific turns slightly orangeish and blue turns darker. Both consoles output rgb and like Chad says rgb color decoding seems to be messed up when you enable that mode. Is there a solution to this? I really want to play my games 4:4:4 but also want rgb to decode the color correctly. How about if i run a component cable to my wii u or get a dvi adapter connected to an hdmi adapter back, maybe it confuses the tv into thinking it is an rgb signal and activates 4:4:4 chroma? Any help would be appreciated, thanks.
post #8 of 8
Jut set the PS3 to output YCbCr... problem solved. The PS3 does a "perfect" conversion between color formats. So when the PS3 is in 720p or 1080p mode, it should be able to output YCbCr no problem. Just find the setting in the PS3 menu system and change it.

The Wii is outputting Standard Def (unless it is a new HD model). Standard Def has 2 issues... resolution and color. The color problem comes from the difference between the Rec 601 SD color standard and the Rec 709 color standard for HD video. When you display SD material on an HD display, the HD display SHOULD convert the 601 color space to 709 color space for proper display on HDTVs. If that does not happen, reds will be too orange and greens will be too yellow. (Blue is not affected much, typically). That said, even if the 601 to 709 conversion is done properly, the original SD color space is smaller than HD color space and reds won't ever look as red as they do on HD displays showing HD (Rec 709) content. So you may always find SD sources have reds (like STOP sign red) that look orange-r than they do in real life.
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