SK-AM62A-LP: How to Tune LSC - IMX219(Greenish circle)

Hello Ti, 

Any update on this??

Hi Atharva,

The VISS-LSC H/W supports color shading, i.e., one 2D LSC LUT per color channel of RGGB.

However, tuning tool only supports one LUT for all colors and therefore you can only input one LUT for shading property in tuning tool.
You would have to use tuning tool for R/G/G/B tuning separately and then interleave the output 2D LUT together.

For your RGGB sensor, the 2D LUT in LSC output xml is in the right order of RGGB.

Atharva Shende said:

1. I am currently working on LSC (Lens Shading Correction) for imx219 (resolution-1640x1232) but where can I find LSC Input Table for that.

Please refer to the plugin guide for the input LUT format.
That input LUT is a property of your lens.
You may get the information from the lens vendor or do calibration for your lens.

Atharva Shende said:

2. I got one input table, but it is not affecting. Here is what I am applying in the dcc tuning tool.

You would need to do it separately for RGGB and then interleave the gains.

Atharva Shende said:

3. I am getting same greenish issue as below

I am not familiar with this lens.
You may check if you can convert their lens shading information to the tuning tool format.

Atharva Shende said:

4. What would be LSC center(horizontal&vertical) for 1640x1232 Resolution?

This depends on how the lens is mounted on to the camera in alignment with the center.
You may take a look the the raw image on a gray chart to see where the center is.

Hi Gang Hua,

After performing LSC from the tuning tool these are the results I am getting so far:

Before applying LSC(Original Image):

After applying LSC:

1. How can I remove that Greenish part?
2. Do I need to apply any other parameters like AWB or Color correction to get rid of that green circle?

Thanks,
Atharva Shende

Hi Atharva,

What LSC do is to apply a 2D gain map on all RGGB pixels.
If we have the same gain map for all color channels, LSC typically makes the dark image corners as bright as image center.
For color shading, gain map for RGGB pixels are different and therefore it similar to applying slightly different white balance at different locations.

You would need to have the correct RGGB gain maps to remove color shading perfectly.
The rings you have suggests that your gain maps are not correct.

You may try to get the 3 separate 2D gain maps (i.e., for R/G/B) to work with LSC plugin without interleaving them.
LSC will give 3 output Bayer pattern images.
If they all look correct without rings, you may check if interleaving the 2D LUTs are done correctly.

Gang Hua said:

You would have to use tuning tool for R/G/G/B tuning separately and then interleave the output 2D LUT together.

Can you please guide us and where exactly need to change gains? because we only have Tuning tool

You would have to get the calibration property for the color shading of your lens.
Please follow the LSC plugin guide for the format of the LUT required as tuning tool input.

Color shading happens because that property is different for R/G/G/B pixels (therefore gray objects becomes colored depending on the pixel location).
I don't have much experience in calibrating lens shading and tuning tool does not support that calibration (it requires you to input the shading property).

Lens calibration is beyond the scope we can support at TI.