Making Video Colors safe for Television Broadcast

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Steinie
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Making Video Colors safe for Television Broadcast

Post by Steinie » 06 Jan 2012, 12:50

Author Jeff Roig:
As 3D modelers and animators we for the most part dont know much about what it takes to make a image/series of images safe for TV and this includes what you would put on a DVD to watch later.
I would not know most of this except for the fact that several years ago I worked for a cable station in the creative department and one of my jobs was to produce a weekly show for the director.
I learned through the technicians there and what it takes to put a video on TV and make it safe to broadcast.
So what I am about to share with you is nothing new its just that you were never told about it.
So with that being said lets learn something new.
Draise this will help you as you can learn how to use broadcast safe colors for your models.
Every image has millions+ colors and also has Luminance and Chroma along with alot of other signals.
We are only going to deal with the color, the Luminance and Chroma.
First a vectorscope is like looking at a color wheel to some degree so long as you look at it this way you will have no problem in understanding it.
Here is two pictures of a vectorscope one is bad and the other is good.
Attachments
Vector Bad.jpg
Vector Good.jpg

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Steinie
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Re: Making Video Colors safe for Television Broadcast

Post by Steinie » 06 Jan 2012, 12:53

Notice I have added a color wheel next to each one to help you understand how they refer to each other.
The vectorscope has limits to it and I have marked those by placing a yellow circle over the limit to each color range.
The green lines you see signify the colors used in the picture.
If the green lines go past the area marked in yellow circles then it is out of its color range and is considered not to be color safe for broadcast.
So what we have to do is to reduce the colors with special filters.

I have also attached two images of what the vectorscope is looking at.
The first image has been corrected and is color safe.
The second image is unaltered and is not safe.
Attachments
Vector Good2.jpg
BAD Sequence 01.jpg
Good Image.jpg

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Re: Making Video Colors safe for Television Broadcast

Post by Steinie » 06 Jan 2012, 12:54

Ok so now for Luminance and Chroma.
While we can see and detect the Luminance with our eyes, you can not see the Chroma.
To view the Luminance and Chroma you need a YC waveform.
Here is a YC waveform.
The first one is showing Chroma and the second one shows Luminance.
Here in the USA we deal with a scale that goes from 7.5 to 100.
So neither one should exceed the value of 100 or go below 7.5.
Once again a filter is used to adjust these levels to get them correct.
The images of Earl in his red truck that I have placed are not finished they are only used as a sample to show what is a good value or bad.
If more of you are interested in this I would be glad to do a tutorial that is more in depth on how this works.
Most good quality video editing software has the vectorscope and YC waveform built in to allow for color correction.
I use Adobe Premiere.
Attachments
Luminance.jpg
Chroma.jpg

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