Colorist Peter Doyle, who pioneered the DI process on The Fellowship of the Ring, is hard at work on his next film, Harry Potter and the Order of the Phoenix. He reveals what he's doing on that film to standardize color space across the production.

Q: Did you standardize the color space at the beginning of the production?

A: Yes, we standardized color space and in some ways more importantly color monitoring.

We built an environment were the filmmakers could review HD rushes in the same screening room as used for previews and final approval of prints. We worked with our telecine vendor to supply a unity log HD telecine, meaning our HD rushes matched our 4K scanners. There was no grading at the telecine stage, allowing for repeat transfers whilst retaining the same color and density.

We graded and monitored in Log, using our print-emulation LUTs. It meant we could run HD rushes and A/B against print and have the same color and density.

A common language was therefore possible, this being printer lights between the lab, the DI room, and the DP. When the morning rushes grading was complete we would deliver to editorial in HD rec 709 and color convert through a transform that is used for the Final DI to HD conversion.

Thus, editorial would see the same grade on their monitors as seen in the grading theatre (within the confines of standard editorial monitoring a la plasma screen and flat screens).

Q: How many outside VFX vendors are you working with? How did you get them in line with this color standard?

A: At least six, with the number to grow as the film evolves. We issued raw scans without conversion (the same as used for DI grading) and supplied notes about our monitoring, e.g. Arri recorder calibration, print aims, etc., and offered grey scales if desired on a Web site, both a neutral grade (to be used and backed into the composite) and a primary (to be used for monitoring). These numbers are simple RGB offsets that are correct when using the raw scan in 10 log. On two sequences, more extensive grading data needed to be supplied, so we exchanged our Baselight database.

The primary advantage is the DP has his work looking the way he designed it. Additional benefits – all departments can see where the film's grade is going. All parties can see what the DP had in mind, and are not surprised by the DI grade. We are able to give a much clearer idea to the VFX vendors about the direction of the grade earlier, so a lot of development work is negated as the composite can be built knowing were the shot is going but with the latitude of being able to grade the VFX to sit with live action.

Ultimately, it makes for a far more consistent grade as all shots are graded with the same package, in context and by the same person. This relates mainly to contrast and density.

The biggest challenge is convincing everyone to "stop tweaking the shots" and ensure their pipeline, mainly conversion to linear then back to log, is correct. Second has been to trust monitoring. We have removed film print from the approval process, which requires a big leap of faith. This is a valid concern, as many people have been burnt over the years with poor color management. However, we routinely print from original neg and compare our HD rushes, and swap printer lights with the lab to ensure we are still in sync. We also record out and review our grades on print, as a reality check against the digital projection