ASC CDL and RSX settings

[jamie parry]

hello everyone
as you probably know i've been doing jamfuze to do offline/online workflow with R3Ds and AVID mxf.
however what i do for a living is work as a colourist

recently I was asked by one of my beta tester guys to put the RSX reading/rendering functionality in the ONLINE bit of jamfuze.
that is make "GRADED" online-quality clips
I was/am a bit reluctant to do this as a colourist I believe it may paint someone into a corner during a grade when the edit has changed or something comes up like an artistic vision someone has that may be difficult to obtain from graded footage.
so I resisted for ages but Howard was so nice i put it in today.
So to the point
the AVID keeps track of the ASC CDL parameters, lots of grading devices understand the SOP and SAT things that the ASC CDL produces...
is there any way i can take the values in the RSX file (seems to be XML like so i can parse it) and make CDL values from them?
I've got a davinci so i can test it out
AVID will put them in the EDL it makes so i can definitely track it through to
the online
then i could render "neutral" footage but still have a look that approximates (closely?) to the vision of the DOP using the CDL values.
this would be cool..
has anyone done this or am i gonna have to buy some more biscuits and learn it all like i did with the MXF stuff?
any help would be great.
j

 

[MichaelP]

I asked this of RED and Assimilate before about using the ASC CDL values as a means of tracking the color parameters but was told that it was not possible. Maybe that has changed, but I don't think so. The ALE file does allow for the tracking of a LUT as metadata where you can track the RSX file name, RLX file name etc that can be passed along downstream for online use. This is something we added to MetaFuze v2.

Michael

 

[jamie parry]

further research

further research

OK
after some biscuits and downloading stuff from the asc
i've managed to make this
*ASC_SOP ( 1.16129 1.22580 1.18279 ) (1.16129 1.22580 1.18279 ) (1.16129 1.22580 1.18279 )
*ASC_SAT 1.41935
rsx values= exposure: 0.4 contrast: 0.1 brightness: 0.2
from the RSX file in the folder
all the values in brackets are just the RGB values from the rsx file written 3 times for Slope Offset and Power
asc sat is just the saturation value from the rsx file
the exposure,contrast and brightness values are all from the rsx file aswell
soooo
i have all these as variables that i can do arithmetic with...
any ideas what i should do next?
i'll mess about and try and do it by eye if i have to but if anyone's done this kind of thing before a little help would be good.....
i'm not trying to get a super accurate RSX to CDL thing (use 3cp if you want that) just a "starting point" for a colourist that
a) isn't a million miles away from the rsx'd rushes/dailies
b)doesn't paint the colourist into a corner (like rsx-ing the online mxf's would)
again it's me doing science experiments in public.....
j

 

[Nick Shaw]

I'm not sure if what you are attempting is possible. As I understand it, the bulk of the image processing in Red Alert is done in linear light, with the output LUT applied at the end of the processing chain. So linear operations based on the parameters become non-linear once the LUT is applied. This will create colour transforms which are not representable by CDL values.

As an analogy, I just did a test in Baselight where I added a video grade (with CDL compatible switched on) and then a Truelight profile into the stack. Then I flipped the order of the grade and the Truelight profile. The result was (obviously when you think about it) very different.

 

[jamie parry]

hmmm trickyyyy

hmmm trickyyyy

thanks nick

I'm not going to let such a small detail as whether its possible to do or not stop me!!!
doing the impossible is fun!
i'll mess about anyway and see what happens.
at the very least i could come up with some "interesting" (that's welsh for shit)
grades....
this cdl nonsense is new to me and i'm not sure how things handle it really. guess i'll have to bite the bullet and upgrade the davinci's software. i hate doing that. gives me the heebie jeebies.

jamie