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Rendering Subtitles in FCP 5.0 (with Kona 3) causes Rendered clips to lose Contrast

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rdomalpalli
Rendering Subtitles in FCP 5.0 (with Kona 3) causes Rendered clips to lose Contrast
on Feb 6, 2007 at 11:26:08 am

Hello,

I'm adding Subtitles to an HD clip that I have in an "AJA Kona3 1080psf 24 10 Bit RGB" sequence preset.
I find that when I add a Subtitle, FCP asks to Render, but when I do so, I find that the Rendered Portions show a loss of Contrast. Any idea how to get around this?
I have a Quad Mac running FCP 5.0.1 and Kona 3 installed.
Thanks in advance for your help.

Regards,
Rajnesh



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John Pale
Re: Rendering Subtitles in FCP 5.0 (with Kona 3) causes Rendered clips to lose Contrast
on Feb 7, 2007 at 9:28:25 pm

I am not sure how to help you, but I think this passage in the FCP manual explains what is happening...



If your video capture codec does not support Y?CBCR processing, your video is
processed in RGB color space. 8-bit RGB video spans 0 to 255 like Y?CBCR, but black is set
to 0 and white is set to 255. In other words, RGB has no headroom, or extra bits, available
to record super-white values. A Y?CBCR level of 235, which is considered white, is mapped
to 255 when converted to RGB. However, what happens to the super-white levels such as
236, 240, 245, and so on? When converted to RGB, all these super-white values are
mapped to RGB 255, which has the effect of flattening all the subtle brightness
differences to a single white value. The result is sometimes referred to as luma clamping,
or clipping. Visually, clamping appears as a loss of details in the highlights of the image,
and a subtle darkening of the brightest values. When Final Cut Pro renders Y?CBCR media
in RGB color space, images with super-white luma levels (101 to 109 percent) are clamped
to 100 percent. This effect is most noticeable when using a transition, such as a dissolve,
between two clips. The super-white areas of the clip that


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