White Balance, Shading Correction, and PRNU/DSNU Compensation

Issue:
JAI cameras support variety of correction/compensation feature, such as

• PRNU/DSNU Compensation
• Flat/Color Shading Correction
• White Balance

On the other hand, behavior and effect of the above feature is sometimes difficult to understand.

Then, here is brief explanation of each feature.

Explanation:

• PRNU/DSNU compensation

This is pixel based *micro* compensation.  Normalize output level of a pixel with adjacent/neighborhood pixels.  It does not compensate flatness/balance of whole sensor area.

You can refer to "PRNU/DSNU Comp." on page 1 in the attached file.

• Flat Shading Correction

This is block based *macro* compensation.  A block consists of certain number of pixels.  The Flat Shading Correction adjust output level to be flat among whole sensor area.  It does not compensate each pixel's micro unevenness.

You can refer to "Flat Shading Correct." on page 1 in the attached file.

• White Balance

The White Balance changes gain (or exposure time) of Red/Blue channels to make a certain pixel's output becomes the same out put level of Green channel at the same position.  The applied gain (or exposure time) affects to whole pixels of each Red/Blue channel regardless of pixel's position.

You can refer to "White Balance" on page 2 in the attached file.

By the White Balance, output level of a certain position of pixel among Green/Blue/Red Channel becomes the same, but portion of Green/Blue/Red Channel of whole sensor area is different.

• Color Shading Correction

This is also block based *macro* compensation.  A block consists of certain number of pixels.  The Color Shading Correction adjusts output level portion of each Red/Blue Channel to be the same portion with that of Green Channel. 

You can refer to "Color Shading Correct." on page 2 in the attached file.

As you can see in the file, after Color Shading correction, each graph's portion of Green/Blue/Red channel is identical, but its level is different.

As you can see the attached file, by combination of each feature, required images would be available.