topic Re: IMX8MP-ISP Calibration in i.MX Processors

IMX8MP-ISP Calibration

jp4 — Wed, 23 Oct 2024 07:15:32 GMT

Hi ,

We are performing ISP calibration for our own camera with IMX662 sensor.

While calibrating AWB parameter, we are asked in the calibration tool to upload CIE_Illuminants.cxf file and here we have uploaded with the file provided by NXP(CIE_Illuminants_cxf).

After calibration, the output is not good as expected when AWB=true, but output is good when AWB=false. We are doubting the CIE_illuminants_cxf which we used during calibration.

FYI, While calibration, We have taken images for D65, CWF , TL84 ,A and HZ using the "X-Rite SPECTRALIGHT QC" lightbox.

Below are the list of points need to be clarified for us.

1. Is it correct to use CIE_illuminants_cxf provided by NXP ? or we need to go for Light box specific?

2. If we need to find light box specific, how to generate CIE_illuminants_cxf file.

3. Under which condition or lightbox was used to generate CIE_illuminants_cxf provided by NXP.

@joanxie

Thanks in advance,

Re: IMX8MP-ISP Calibration

joanxie — Thu, 24 Oct 2024 05:25:45 GMT

I don't have such tools, so I consult this from ISP team, I was told this file is a standard illuminant file, which is offered by the VSI tool, for other information, you can refer to the

https://en.wikipedia.org/wiki/Standard_illuminant

you also can refer to the chapter Chapter 8
Auto White Balance Tool of ISP Calibration Tool Suite User Guide

Re: IMX8MP-ISP Calibration

jp4 — Thu, 24 Oct 2024 10:53:26 GMT

Hi @joanxie ,

I need a small clarification on ISP Calibration Tool Suite User Guide Chapter 6 Lens Shade Correction Tool,

As per the manual, I need to adjust Exposure to get highest pixel value in the center of the image is about 220 (for 8 bits per pixel). In this statement it has been mentioned for 8bit per pixel.

In my case I have 12 bits per pixel, so what pixel value in the center of the image I should ensure? and is there any way to find center pixel value using tuning-client tool.?

Thanks in advance.

Re: IMX8MP-ISP Calibration

joanxie — Mon, 04 Nov 2024 04:33:28 GMT

sorry for my delay, I took annual leave last week, I will update this on your new thread

https://community.nxp.com/t5/i-MX-Processors/IMX8MP-ISP-calibration-AWB/td-p/1985987