Messages

thanks chmee !

Actually I think  your diagram is a  lot better than the Wikipedia one - it's clearer and simpler! ...  not even I understand the Wikipedia version in detail.
And maybe - if we keep this thread alive we can gather more and more information. 

Here another interesting image from Wikipedia on how the image-processing-pipeline of Nikon works.
I guess the structure of processing in Expeed will be somehow similar to the Digic process:

en.wikipedia.org/wiki/Expeed#mediaviewer/File:EXPEED_Milbeaut_M42.gif

@chmee : Thanks for this interesting image !!!

Do I understand that right?: The Canon picture styles are embedded in the process to create the Low Dynamic Pictures, therefore the picture styles could change how the white and black levels are clipped ?

Stevefal started a similar thread regarding questions of the "Canon image dataflow":

http://www.magiclantern.fm/forum/index.php?topic=4830.msg132823#msg132823

I post this into the Post-processing forum, as there is no real pre-preprocessing forum:
I am wondering which are the processes done by the camera's processor for creating an 8bit video file:

As far as I understand it now, the following steps have to be done(or many more?), but which is the correct order?


CMOS Chip - Light detection: The matrix of G-R-G-B is read via a bayer sensor:
Camera Processing: 
- De-bayering 
- Converting 14bit raw to 8bit (how is this done in detail?, is it only clipping  or something like tone-mapping?)
- transferring image data the linear light to log (gamma)
- Adding the canon pictures style - presets (after or before the conversion to 8bit )
- Image optimizations (which ones do exist) sharpening process, ...
- Data transform to YcbCr
- Chroma subsampling process (4:4:4 to 4:2:0)
- Transferring the series of images into a movie container: Quicktime
- movie compressing: inter- and/or  intra-frame (mpg4, h264)

At which stage are the canon picture styles embedded?
Can I influence with the canon picture styles the conversion from 14bit raw to 8bit?

Thanks for any suggestions or ideas !

Dear Stevefal,

I was very happy to discover your questions about the implementation of the picture style and the consequences to the image quality.
Could you or anyone in the forum solve/answer your original questions? - THX !

1) When experimenting with "contrast" within a picture style, my impression is that lowering contrast brings a little more information from the 14/12 bit domain, via scaling, into my image (at the inevitable expense of more banding). Is this correct, or does contrast merely alter gamma within the 8-bit space?

2) The Picture Style Editor's curve UI seems only to alter dynamics post 8-bit conversion. That is, you can't use it to recover highlights or shadows from the RAW 14. Is that right?

3) If #1 and #2 are correct, my most important question is whether 3rd party picture style developers have access only to the mostly pointless parameters in the Picture Style Editor, or do they have back-door access to parameters governing the actual 14/12>8 bit conversion algorithm?

4) If it's the latter, what freedom is available for controlling the balance of truncation versus scaling during the conversion? Why don't style developers simply explain what their profiles do in terms of scaling and truncation? This is a math problem, but people seem to treat it as black, uh, magic.

When preparing to shoot a scene, I would like to measure the scene's physical dynamic range using a light meter or camera (or ML feature!) and then based on those measurements and a well documented set of 14>8bit conversion profiles, pick the best one for the shot.

P.S. Does anyone know exactly what HTP does? Does it linearly scale 14>12? Or does it non-linearly scale the top few bits of the 14 into the top few of the 12? Something else?