Creating a custom IDT

Discussions - Using ACES Tech/Engineering
1

Hi there,

Is there anyone that can help me create an IDT? Or point me in the right direction; is there a thread or topic on this forum or a guide that shows how to do that in steps? I’ve found the document about exposure equation on the working group page, I don’t have any information about Exposure, Exposure Index, I do have log curve formula and rgb white point. Would I still be able to bring this material into ACES?

linear sensor data converted to log formula is:
(x> cut)? C * log10(a * x + b) + d: g * log10(e * x + f) + h

cut 0.0387
a 40
b 4
c 0.7192
d -0.1958
e 40
f 0.09303
g 0.2779
h 0.2796

primary x,y
g 0.310, 0.595
b 0.155, 0.070
r 0.630, 0.340
white d65 0.3127, 0,3290

2

@nick is your man for custom IDTs!

3

Those appear to be the primaries of SMPTE 240M or SMPTE C. That’s a bit unusual, but not unheard of.

If you want to try to make it yourself, you can use a DCTL IDT like one from here as a template. You need to get the matrix values for SMPTE 240M to ACES2065-1, with either CAT02 or Bradford adaptation, which you can get from here.

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