[FFmpeg-user] [Cin] FranceBB's LUT collection

[Andrew Randrianasulu]

пт, 16 июл. 2021 г., 09:36 Andrea paz via Cin <cin at lists.cinelerra-gg.org>:

> I made a forum post to keep track of the repository. So if a request
> is made we can direct to that post.
>
>
> https://www.cinelerra-gg.org/forum/help-video/francebb-luts-for-space-color-conversions/


It was updated yesterday with interesting message:

https://forum.doom9.org/showpost.php?p=2018552&postcount=310

==== quotation start ===

This feature was requested by ossnorry.
As a bit of history, in 1953 the NTSC version of BT601 was born, however
the tube phosphors originally used by the TVs of the time had issues
displaying those values and the standard was later changed (reduced) in
1987 to make life easier for the hardware of the time, however one country
never stopped using the original NTSC version and that country is Japan,
which is why the original NTSC version has become known as "NTSC-J" which
stands for "Japan".

Anyway, the old BT601 NTSC Japan (1953) is based on the following values:

x white = 0.3100
y white = 0.3160
x red = 0.670
y red = 0.330
x green = 0.210
y green = 0.710
x blue = 0.140
y blue = 0.080

and is indicated with
--colormatrix smpte170m --transfer bt470m --colorprim bt470m

while the normal BT601 NTSC SMPTE C (1987) that all other NTSC countries
adopted has the following values:

x white = 0.3127
y white = 0.3290
x red = 0.630
y red = 0.340
x green = 0.310
y green = 0.595
x blue = 0.155
y blue = 0.070

and is indicated with:
--colormatrix smpte170m --transfer smpte170m --colorprim smpte170m


As you can see, all values are different, including the white point.


=== end of quotation ====

I surely recall Japan was different, but it completely evaded my mind that
old NTSC 1953 was still in use there up to relatively modern times!


cc ffmpeg-users because it tend to be more popular list, so visibility will
be higher.




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