Remove Banding in sky

[Mike Harrington]

i need a bit of help removing some banding in a bright blue sky

I shot some fighter jets on RED, and converted to Cineform and my final output is PhotoJpeg Quicktime (not my choice)

I am thinking the 12 bit to 8 bit drop is leading to the banding...
any clues as to get rid of this crap
I know one way is to implement some type of dithering(not sure how)
Ideally there would be a better way to compress the data to 8 bit....perhaps

thanks

[David Newman]

Yes, PhotoJPEG not the best choice, but it will do if you let the bit-rate climb. Place the CineForm master into an AE composite, set the comp to 16-bit mode. Add a 16-bit noise filter with 0.4% noise (1-LSB of 8-bit worth of noise) then encode to PhotoJPEG at a high quality setting. If you still see banding, bump the noise. This is the dithering you need.

[Mike Harrington]

thank you David....
can you explain the logic behind the .4%
specifically decoding what you mean by 1-LSB

Thanks again

[David Newman]

8-bit is 256 levels. 1-bit or the LSB (Less Significant Bit) 1/256th of the full range. 1/256 = 0.0039 or approximately 0.4% of full range.

[Mike Harrington]

thanks...appreciated as always..
might delve more into this using google later..