Extracting the Y, U, and V components from a YUV source

[vhelp]

Hi everyone

What function can I use to extract each of the YUV components: Y, U, and V ?

I need to extract from the raw source, no conversions to something else and then.

I know about the Greyscale() function, rec709 and rec601, but that will not give me what I actaully need. It basically blends channels and gives you no other user options.

ShowRED, GREEN, and BLUE, are basically same as above, they blend channels or in this case, will give me an r, g, or b component, which is not what I am after.

I did a quick look up and did not see any ShowY, ShowU and ShowV.

If it helps, here are some examples I made with the ShowRED, ... functions, which is not what I'm looking for:



* original image -> showRED converted


* original image -> showGREEN converted


* original image -> showBLUE converted


Thank you.

-vhelp 5306

[ronnylov]

Maybe some of these avisynth functions can be useful:
http://avisynth.org.ru/docs/english/corefilters/swap.htm

UtoY() would make a greyscale clip of the U channel.
VtoY() would make a greyscale clip of the V channel.

[jagabo]

For YUY2 video:

src=DirectShowSource("YUY2Video.avi")

Y=ColorYUV(src,off_u=-256, off_v=-256).ColorYUV(off_u=128, off_v=128)
U=UtoY(src)
V=VtoY(src)

StackHorizontal(Y, U, V)

Note that YUY2 video has U and V channels that are half the horizontal resolution of the Y channel. Y:U:V:



For YV12 video:

src=DirectShowSource("YV12Video.avi")

Y=ColorYUV(src,off_u=-256, off_v=-256).ColorYUV(off_u=128, off_v=128)
U=UtoY(src)
V=VtoY(src)

StackHorizontal(Y, StackVertical(U, V))

Note that YV12 video has U and V channels that are half the resolution, both horizontally and vertically, of the Y channel. Y:U/V:

[vhelp]

While I do appreciate the tips on manipulating clip to show gray levels through ColorYUV and U/VtoY it does not seem to be what I'm looking for. This method leaves me wondering or doubting what my sources Y and U, V true value are. This is assuming from an analog capture project where I capture raw and no codec.

I will continue searching through google for the answers. I know I've seen the answer on a forum board somewhere, but can't remember. But its looking like I may have to create the methods (the hard way) myself. Again, thank you for the above tips.

-vhelp 5309

[jagabo]

UtoY() and VtoY() simply copy the values from the U or V planes to the Y plane. The values you then see in the Y plane are then exactly the same values they had before being copied there.

Setting U and V to 128 leaves you with perfect gray scale. The values in Y are untouched.

These are exactly analogous to your ShowRed, ShowGreen, and ShowBlue where the individual primaries are converted to grayscale by copying one primary to the other two.

If your frame is YV12 you can export as a binary file. You will then have three planes of data Y, U, and V. Remember that the U and V planes are half the resolution (both axis) of the Y plane.