Working Color Space: What Colorists Aren’t Telling You

Almost without exception, colorists on YouTube who recommend using a working color space other than the native color space of the camera do so without explaining to their followers that this requires making a viewing LUT during pre-production. It’s difficult to conceive how anyone preoccupied with color management could overlook this critical detail. The following remarks from a post by Rand Thompson concern ACES and RED RAW but apply equally to DaVinci Wide Gamut Intermediate or any other non-native color space and any camera.

In a typical RED IPP2 workflow, “you could include a Creative RWG/LOG3G10 LUT along with whatever chosen IPP2 Output Transform you wanted and shoot with that. Then a DIT would probably make CDL corrections that were according to the DP or Director and pass those CDLs along to the Colorist to add to the Post Production Grade for further color grading..”

If instead you were monitoring RED IPP2 on set and decided to go with ACES in post, you

“…would be starting from a Look with different Tonality and Color Rendition that neither the DP, Director and DIT had started out with or agreed to in Production nor what the DIT had made CDL correction for. So now it’s up to the Colorist to make it resemble the look that was established in Production which will be very hard if not impossible to achieve.”

The correct way to proceed would be to

“develop a LUT that could replicate an ACES workflow that would include the IDT( Input Display Transform) , the RRT( Reference Rendering Transform) and ODT( Output Display Transform) and which also included the the correct Transform from a Specific Scene-Referred Color Space to the desired Output Display…”

“… The purpose of the RED IPP2 Transform is to Transform a REDWideGamutRGB/ LOG3G10 Image to a Desired Output Display. That requires a LUT or other tool that can take a REDWideGamutRGB/ LOG3G10 Input and transform that image to a different Output Color Space in this case REC709/BT1886 Gamma 2.4.

So If I use two ACES TRANSFORMs with one having as its INPUT RWG/LOG3G10 and another which has as its OUTPUT REC709/BT1886 it should have all of the components needed along with the required IDT,RRT and ODT to display an ACES workflow properly with a RWG/LOG3G10 Image. You can also use a “LUT BOX” that would go between the Camera and Monitor with a LUT that you could monitor for an ACES Workflow.”

“Now of course the LUT that would actually be used would be designed by a Color Scientist working on a film or a Talented Colorist who would use a LUT Creation Program from maybe Light Illusion or Lattice or some other High-End LUT creation program or it could be a Program that was designed from scratch by the Color Scientist or Colorist. This LUT would go through vigorous testing, be 65 Cube sized or even larger and have a Bit Depth of 10 or 12 Bits.”

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