Re: [GM-core] re DPX log image

On Sun, 10 Apr 2005, Robin Rowe wrote:

> Bob and I have had some DPX discussion off-line. This is to recap.
>
> Bob says the DLAD test image is linear, not log, and asked if I could get him 
> some DPX log images for testing. I don't have any images cleared to release,

I believe that I have now successfully written and read a 10-bit DPX 
log image.  CinePaint does not recognize it as such.  It loads the 
image all washed out looking.  In fact, it entirely ignores the 
transfer characterisic value, and writes 0 for the transfer 
characterisic when it writes files.

I have created a new DPX sample file package which includes DPX images 
using log encoding for both grayscale and RGB.  The package is 
available at "ftp://ftp.graphicsmagick.org/pub/outgoing/dpx_samples.zip".

The translation from linear RGB to log supports up to 16 bits of 
resolution, but the current translation from log RGB to linear 
currently only supports 10 bits of resolution.  With some fixes to the 
math, it should be possible to support up to 16 bits of resolution 
when converting from log RGB.  12 is likely to be sufficient though.

Bob
======================================
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/


-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click