CosmeticCorrection process problems

Jkcolli

Member
Aug 15, 2018
11
0
  • I have been using the Auto Detect section of CosmeticCorrection process.
    I am using a Canon 70D DSLR(14bit) and processing the raw files.
  • The CFA box is checked.
  • The Amount is set to 1.00.
  • The Use Master Dark box is not checked.
  • The Use Auto Detect box is checked.
  • The Hot Sigma box is checked.
  • The Cold Sigma box is not checked.
I am varying the Hot Sigma value to test out the CosmeticCorrection process.

Using the CosmeticCorrection Process
When I set the value to 50 when using the CosmeticCorrection process, I would expect very few if any pixels would be corrected.
I find when I look at the Real Time preview that many pixels will be corrected.

I looked at the value of a particular pixel to be corrected and the pixels surrounding it. The values and the convolution matrix are shown below:

Convolution matrix
1,0,1,0,1,
0,0,0,0,0,
1,0,0,0,1,
0,0,0,0,0,
1,0,1,0,1

The center value = 0.18314

The eight surrounding pixels used for convolution:

0.03159​
0.03243​
0.03287​
0.03218​
0.03189​
0.03090​
0.03119​
0.03337​

Surrounding pixel Average = 0.0315
Center Value/Surrounding Pixel Average = 5.715
So I would expect the center pixel would not be corrected until the Hot Pixel value was set below 5.715. This is not the case, it is always corrected regardless of the Hot Pixel value.

Using the Cosmetic Correction script
I am also trying the script written by Nikolay Volkov(~2012). This script works exactly like I would expect.
In my example above the center value is not corrected until the Hot Pixel value is set below 5.715.


I have tried the CosmeticCorrection process on several raw files and several hot pixels in each file.
The results are always the same.
I wonder if Auto Detect is always using the default Hot Pixel value of 3.0.

Jack Collins