Sunday, October 12, 2008

Playing with encoding curves.

As a gift for my 40th birthday, my wife got me the awesome 2nd gen. iPod Touch. I've been playing with a Graphing Calculator app, experimenting with various video encoding curves.

Legend.

Red - Linear
Blue - Gamma 2.2
Green - RedLog (Silicon Imaging Log-90 is very close)
Yellow - RedSpace

Todo -- Add PanaLog and Viper Filmstream

3 comments:

teemujin said...

Hi Ive been tinkering with FirstLight and Cineform stuff to convert my Canon 60D footage and tweak colors.

Im still trying to understand the encode curve... your manual says 'most cameras' use 2.2... and I tried that setting.. but for some reason - I really like the Log90 setting better on all the footage... I still display at gamma 2.2 because I know my monitor is putting that out.

Can you explain the encode Log90 a bit? What is this setting really used for... and is it ok to use it based on what Im seeing? or am I just introducing problems by tinkering in places I should not be?

David said...

Wow! Such and old post to comment on.

You are doing nothing wrong, and I to sometimes mess with the workspace curves to begin a color correction. This particular change acts a gentle contrast reduction, somewhat expanding the perceived dynamic range.

Workspace curves are needed as FirstLight generally doesn't know how the source originally converted linear light to image data. We need to know how to convert back to linear or mathematically correct white-balance and exposure controls, all other operations are unaffected. This is a creative process, so mathematically correctness is not all that important.

teemujin said...

Sorry for the old posting post! :)

Just that I was digging for some deeper explanation of Log90 and this was all I could really find...but glad to hear it from the scientists themselves that its a-ok to use a Log90 curve on footage that probably was not captured in Log90 format... I wonder where I can find out the 'actual' gamma capture curve of specific Canon cameras? I don't think thats written anywhere in the docs for these cameras... hmm.

thanks again for the reply!