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Color space Police!



        For years now I've heard reference within a Telecine suite about
the chroma police. I've even made reference to this organization. However,
I would like raise a pointed issue. They don't exist my fellow artists. And
in their absence various ambiguities have arisen.
        What has happened with this lack of proper officiating is
devasting. Television stations, duplication facilities, post production and
editorial shops across the country have developed their own color space
standards. And thru all this the art that we create is tested, and then
modified to fit each given scenario. Often these adjustments are made by
informed engineers who use their expertise and discretion to achive optimum
broadcast standards. Or such a case arises as when I was technical director
for on-air opertions at a broadcast facility. Looking up from a monitoring
station I noticed an operator adjusting the TBC of a live machine. When I
approached this individual about his intentions I was informed, " The
preview and program color monitors didn't match color wise so I thought I'd
try to make them closer."
        It is my sincere hope that this individual is now a cashier at
K-Mart and rides the bus to work!

        How about a small request?

        The TIG with its vast knowledge and connections could possibly step
up and create the standards necessary for uniform practices. The
manufacturers and users in this network are by far the single most
concentrated group of color experts. How about it folks! It could be just
what the art director ordered.

        In the mean time I would like to gather as much input about color
broadcast specifications, as defined within this group, as I can.

1.     Black level clip
        a. component
        b. composite

2.      Peak luminance clip

3.      Color information
        a. component clip level
           RGB and Y,R-Y,B-Y
           how are you monitoring (scopes)
           what devices you are using for clipping
        b. composite clip level
           encoder clips and filters
           waveform and vector placement (levels)

        Please include any examples you may have of errors caused by such
issues as negative black (don't even think about going racial), chroma
excursions (no Tahiti vacation photos please) or overly aggressive white
levels (high school essays on "The Discovery of America" will not be
accepted).

        Got a ride that has few speed limitations. Been clocked at 138
chroma/luma and taking the vector turns a little wide at 75% as monitored.
They say slowing down to 120 and learning to stop on the box can reduce
speeding tickets. I'd really like to know why I need slow down, watch my
turns and control my braking when there are no posted signs?

PS      I realize that some of these issues were covered earlier this year.
What I would like to see is something comprehensive in its approach. In
other words "Lets make it stick". Publication in SMPTE and recoginition by
ITS for the TIG's set standards would be a huge step toward limiting the
term "Never Twice the Same Color".
        Europe must be howling in laughter about all this!


Best Regards,
Drew Marsh
Senior Colorist
The Filmworkers Club/Dallas
go fish

" If you're not dangling a line, and wetting a hook.
        You're not going to catch a fish."


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