Thoughts about red channel clipping

Started May 2, 2013 | Discussions thread
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Re: Thoughts about red channel clipping
In reply to Adrian Tung, May 3, 2013

Hello Adrian, my experience with almost every camera i have tested and worked with is that they "do not clip the red channel first". Rather red chnnel clipping is a construct of the in camera processing.

Note I am talking RAW filed not jpegs.

In fact the red channel on many cameras is actually the least exposed under normal lighting and needs the most gain applied to bring it up to the other 2 channels.

The histogram on the camera will often indicate a clipped red channel, but this is based on the jpeg data not raw data.

The upshot is that the green channel usually clips first and the red last ( generally, but this is light and subject colour dependent).

The red channel usually only clips in Raw on really intense bright reds, for example red traffic lights.

Ultimately I have found with many cameras the lying histogram can lead folk to inderexpose the image and in particular the red channel, leading to higher noise in the ref channel and nasty noise patterns overall. The Sony A900 is a classic example of this.

For several years I have shot through a combination of red/magenta filters to get perfect on sensor white balance. After thousands and thousands of images I can say that clipped red channel data has been pretty rare, and you would probably assume the filters would make it worse. They don't, instead they improve overall colour.

I agree Gamut issues will cause problems also.
Hope it helps
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Trying to make the complex simple

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