Vignetting coefficients

[Stephan Weber]

Hi,

I want to follow or create a certain vignetting compensation:

x y(wanted)
0.0  1
0.1  0.95
0.2 0.85
0.3 0.8
0.4 0.75
0.5 0.75
0.6 0.75
0.7 0.75
0.8 0.72
0.9 0.65
1.0 0.58 

So it has a peak left (=middle),  then flat, then the usual outer compensation.

If I know the formula, it should be easy with Excel.

But it looks the coeffs are not a simple polynominal. Can you tell me the formula? I am using v12.27.

Bye Stephan

[Erik Krause]

Am 28.06.2026 um 16:01 schrieb Stephan Weber:

> But it looks the coeffs are not a simple polynominal.

See here:
https://groups.google.com/g/ptgui/c/0PU_2CX4Ofs/m/-5tniAVPDwAJ

--
Erik Krause
http://www.erik-krause.de

[PTGui Support]

Hi Stephan,

If I remember correctly, the first (x^0) coefficient is always 1. So the
curve always starts at 1.0.

The radius is normalized from 0 in the center to 1 at the corners. For
circular fisheye images this means that only the part between 0 and
sqrt(2)/2 is actually used, and PTGui will show only that part of the
curve in the Exposure/HDR tab.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

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[Stephan Weber]

Hi Joost 

I wonder what is the full formula?

I manage to adjust by hand some simple cases which I use when the optimizer does not work.

But how can I get these more difficult table?

I need a rounding for app 20% , then flat  then a quite standard roll off.

With a 10th polynomial it should be possible to get an overall error well below 0.01 rms.

Bye Stephan 

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