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Re: DXL Millennium and 8K Monstro

Re: DXL Millennium and 8K Monstro


Pawel Achtel, ACS
 

Jonathon Sendall wrote: “…is there any jiggery pokery before RAW gets dropped into any NLE or colour grading scenario…”


I compared colour gamuts and colour accuracy of both cameras and there appears to be some differences as well as common traits.

 

The test was performed using IPP2 pipeline, REDWideGamutRGB using RCX and outputting REC2020 to monitor.

Both sensors were exposed to all visible monochromatic spectrum projected directly on the sensors using laboratory-grade monochromator, which is much more accurate than using colour charts.

 

Both cameras reproduced greens and cyans significantly de-saturated compared to REC2020 target.  Monstro appears to have slightly deeper, more saturated greens.

Monstro covered REC709 green saturation, whereas DXL2 didn’t. None of the cameras could achieve P3-DCI saturation of greens and fell way short of target REC-2020 green saturation.

 

Saturation as well as accuracy of blue colours was very good on both cameras.

 

Colour shifts in DXL2 were significantly larger than Monstro’s, turning red colours into magentas (line of magentas in CIE should be clear in an ideal case).

Below are CIE 1931 chromacity diagrams of all visible monochromatic colours reproduced by both cameras: Monstro and DXL2 respectively.

 

Figure 1RED Monstro

Figure 2Panavision DXL2

Below, vector scope outputs. In ideal scenario, the scope should resemble a pizza with magenta slice entirely missing (because magenta is not a monochromatic colour). Clearly visible is a shift of red towards magenta as well as desaturated greens observed on CIE chromacity diagrams.

 

Figure 3RED Monstro

Figure 4Panavision DXL2

Another problem we encountered was with RCX in that it significantly affected the colour vector as well as saturation of monochromatic colours with colour temperature adjustment.

In an ideal world, monochromatic colours should be invariant to colour temperature change, but this doesn’t appear to hold true in RCX (presumably a bug).

 

Hope it helps.

 

Kind Regards,

 

Pawel Achtel ACS B.Eng.(Hons) M.Sc.

“Sharp to the Edge”

 

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