PLR

Some attempts to reverse engineer the PLR high dynamic mode from CMV12000.

1 Registers

• 79: Number_slopes: 1,2,3.
• 75-78: Exp_kp1, Exp_kp2: exposure times for highlights (same formula as Exp_time)
• 106: Vtfl2, Vtfl3: knee point locations (range: 0-63; units: unknown)

Let's check the effect.

1.1 Register effects

I'll use an IT8 chart, exposed at 30 ms (normal exposure), 100 ms (a bit overexposed) and 300ms (really overexposed). A little dark in the lab today, but shouldn't be a big problem.

To analyze the images, I'll use octave 4.0, compiled with 16-bit image support. The scripts should run in Matlab as well, with minimal changes.

1.1.1 Linear exposures

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• 

Let's check if the first image is really exposed to the right, in octave.

a = read_raw('30ms-lin.DNG');
prctile(a(:),99) - 128        % note: black level is forced to 128 in raw2dng
ans =  2269                   % clipping starts at about 2400-2500 above black

[to be continued]