NTSC-safe colors in Blender

Support Basics & Interface
1

Hi,

Is there a way to render using only broadcast-safe NTSC colors in Blender (or does it need to be done in the editing program?) If it needs to be done with a filter in an editing program, will that reduce the quality of the image?

Thanks!

2

You’ll need to do it with a filter in post. It won’t really reduce the quality of the image since you’re clamping the colours down, not stretching them up, so the software dowsn’t have to interpolate.

3

for virtualdub you can find a ntsc-safe filter
with this you can convert your movies fast
virtualdub.org

4

Hm. Am I misinformed again? Does NTSC not use RGB?

5

Well technically, it uses YUV or something like that, but what louki2 is talking about is the legal broadcast luminance/chrominance range of PAL and NTSC. The colour gamut for broadcast video is quite a bit smaller than the available gamut of RGB. This article I googled up has some info: http://www.lafcpug.org/basic_range_check_filter.html and some really techy stuff here: http://broadcastengineering.com/ar/broadcasting_monitoring_digital_video/

6

That’s kinda off topic, but what’s the difference between YUV and YUV2?

Martin

7

I have a feeling it’s to do with the sampling rates, though I’m not 100% sure. I think sometimes YUV is used to refer to YUV 4:1:1 sampling, while YUV2 refers to YUV 4:2:2 sampling. However, I’ve seen YUV used in a general context as meaning ‘an image made up of Y, U and V channels’ no mattter what the sampling rate. I’ve also seen terminology like YUV422, which is explicitly meaning YUV 4:2:2. It seems all a bit muddy, to me.

Some info: http://www.studio1productions.com/Articles/411samp.htm

8

thanks, that cleared some things up.

Martin

9

I work with television colors (as a colorist, not doing 3d for a living) and I’ve never heard of YUV2. But then again, when I went to school and learned about these things 15 years ago there were no DVcam and no 4:1:1 sampling. all there was was 4:2:2 Betacam SP, and also some telecines gave out the super quality of 4:4:4 RGB and even a 4:4:4:4 YRGB. So maybe I’m just getting old… :expressionless:

10

Hey all,

If anyone is interested, there’s a table of some common YUV sampling rates here. Technically, the chart is for YCbCr colorspace, but it applies to YUV sampling too; just change the C to a U.

11

Does anyone have a definite answer on the YUV/YUV2 issue? I’m interested to hear another take on it :slight_smile:

12

Technically, YUV is the colorspace used in PAL television signals and is one of a variety of colorspaces that have one luminance and two chrominance channels. The Y component comes from the standard CIE 1931 XYZ.

YUV uses D65 as its whitepoint.

If R, G and B are expressent in the range [0,1], Y also has a range of [0,1]; however, U and V can be negative as well as positive.

The conversions to and from RGB are as follows:


RGB -> YUV

Y = ( 0.299 * R) + ( 0.587 * G) + ( 0.114 * B)
U = (-0.147 * R) + (-0.289 * G) + ( 0.436 * B)
V = ( 0.615 * R) + (-0.515 * G) + (-0.100 * B)

RUV -> RGB

R = Y + ( 0.000 * U) + ( 1.140 * V)
G = Y + (-0.396 * U) + (-0.581 * V)
B = Y + ( 2.029 * U) + ( 0.000 * V)

Used causally and even in many sets of programming documation, YUV refers to and colorspace which uses one luminance and two chrominance components including but not limited to YUV, YIQ, YCbCr and YPbPr. In my experience, YUV usually refers to YCrCb or YCbCR, not the colorspace of PAL.

YUV by itself can refer to any of the above colorspaces, and should not imply a particular sampling. YUV12 refers to YUV colorspace sampled at 4:2:0 and YUV2 refers to a YUV colorspace sampled at 4:2:2.

PS. If I erred anywhere, please let me know!