What's the difference between NUC and FFC?

[doxuya]

Hi, what's the difference between Non-uniform correction and Flat field correction? Thanks.

[netchuck]

A NUC describes the per pixel corrections that are applied to make all of the pixels in the array appear uniform.  For them to be uniform, they should all provide the same output value for the same scene.

An FFC will create an offset map per pixel that makes each pixel have the same value, when looking at a Flat target.

A two point NUC will also create a gain map per pixel to compensate for the different Gain that each pixel has, so that when looking at scenes with different levels, the pixels will still be uniform.  This is typically done by using a “hot” and “cold” target.



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[bap2703]

FFC usually refer to a 1 point correction done over a factory calibrated correction. The latest having 2 or more points.

But that's just usual, in essence they are all the same thing.

[Ben321]

NUC I think refers to compensating for differences in the physical array of sensors themselves. No manufacturing process is perfect.
FFC I think refers to compensating for background gradient. The middle part of the convex focusing lens is thicker than the edge of the lens, so the middle part of the picture will have be more strongly effected by the IR emitted by the lens itself. This means that you need to subtract the background gradient caused by the lens to get a flat image, so that when looking at a surface with uniform temperature, the pixel values across the image will be uniform when that surface is imaged.

[Bill W]

NUC I think refers to compensating for differences in the physical array of sensors themselves. No manufacturing process is perfect.
FFC I think refers to compensating for background gradient. The middle part of the convex focusing lens is thicker than the edge of the lens, so the middle part of the picture will have be more strongly effected by the IR emitted by the lens itself. This means that you need to subtract the background gradient caused by the lens to get a flat image, so that when looking at a surface with uniform temperature, the pixel values across the image will be uniform when that surface is imaged.