Low contrast after calibration

[Florian Höch]

If you notice on that google sheet, the gamma plot for L* (blue solid line) has this discontinuity near black.

You have an error in the formula:

=IF(B7<=(216/24389),(100*B7)/(24389/27),((B7+0.16)/1.16)^3)

should be

=IF(B7<=0.08,(100*B7)/(24389/27),((B7+0.16)/1.16)^3)

[Pneumatic]

Thank you!  That looks correct now 🙂

Of course I’m curious to know why my Y/Yn was off by…a multiple of 10?

In the Poynton article it says “if you normalize luminance to reference white then you need not compute the quotient”  which I was under the impression is what column B is as it’s normalised to 1.0 as the maximum.

But obviously that must be wrong, just don’t know why 🙂

• This reply was modified 6 years, 1 month ago by Pneumatic.

[Florian Höch]

Of course I’m curious to know why my Y/Yn was off by…a multiple of 10?

(216 / 24389) is for the other direction (Y to L*), which uses the inverse formula. The 0.08 comes from (24389 / 27) * (216 / 24389) * 0.01 so it’s just a simplification of that.

[Pneumatic]

*facepalm*

Thanks.

• This reply was modified 6 years, 1 month ago by Pneumatic.

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