Noise evaluation terminology

[astropixel]

A dumb question - two dark frames one taken at 0C and the other at 16C

This is the noise evaluation output;

Code: [Select]

(16C image)
IMG_8727
Calculating noise standard deviation...

* Channel #0
?K = 2.562e-04, N = 4898476 (39.98%), J = 4

(0C image)
IMG_8726
Calculating noise standard deviation...

* Channel #0
?K = 2.360e-04, N = 7129792 (58.19%), J = 4
The standard deviation (sigmaK) of the grayscale 0C image is less than the 16C image. What do the other figures represent? N=value (value %) J = 4

It has been a long while since referring to any of this and the terminology escapes me.

[mschuster]

Roughly, the method ignores pixels near significant small scale structures at wavelet layers below J.

The remaining N pixels (or % of total number of pixels) are measured for noise.

Mutiplty sigma by 65535 to estimate the standard deviation of noise in DN, here ~17 and ~15.

Thanks,
Mike

[astropixel]

Thanks Mike.