imx95 isp tuning

[yancheng]

Hi imx95 isp team,

About gtm/ltm tuning, 2 questions need your help.

1> For GTM LUT, setup 416 values, profiled as below left, how to understand the input and output of GTM?

2> For LTM LUT, setup 1024 values, profiled as below right, we know it split the image into 32x32, how to map each block to high/mid/low brightness zone?

Any method to get the suitable gtm/ltm profile?

   

Thanks,

yancheng

[yancheng]

@Alan_Jia, could you push the issue. thanks~

[Alan_Jia]

Hi @yancheng,

I will check and reply you ASAP.

Best regards,

Alan

[yipingwang]

Firstly, the GTM and LTM DRC is used to enhance the performance of high dynamic range sensors like WDR. For linear sensors, GTM/LTM takes very limited effect.

As for the LUT, the LUT for GTM/LTM can change dynamically. To apply a fixed LUT, you need to change the UPDATE POLICY of GTM/LTM to ON_CONFIG then import your LUT. There is a way to visualize the LUT. In AGLBCE module, click generate and a window will show like below:

You can see the GTM/LTM LUT as below:

Global: 

Local:

The tuning tool user guide will have more information about how to interpret those two charts.

[yancheng]

Thanks for your reply! 

 GTM/LTM should change dynamically by setting to ON_PROCESS based on the input LUT parameters. The 2 LUT maybe strongly effect the GTM/LTM performance. AGLBCE just shows the 2 LUT data and cannot adjust it. So how to calibrate the 2 LUT parameters to get good performance(hdr, contrast, ...)?

Thanks~

[yipingwang]

Basically, you need to follow these steps:

1) Start Camera, connect to the device via tuning tool.

2) Read dynamic parameters in “Live Control – Metadata”

3) Check the dynamic params for the scene (exposure, again, hdr_ratio, y_level,

lux_level)

4) Check the preview, capture raw/yuv images.

The AGLBCE WDR default tuning is split for example 2d interp of hdr_ratio and

lux_level to cover different scenes. For example hdr_ratio 1k, 2k, 5k, 10k, 40k,

>100k and lux <1k, >2k - for normal and high light. Interpolation is between them.

5) Find the region based on dynamic params and adjust tuning (via live tuning)

and check the preview/capture images (Raw image could be also PC simulated

instead live tuning).

6) Save the project when satisfied.

7) Test at different scenes and repeat. HDR studio scene with different illumination

level ratio between dark and bright side could be starting point.

The tuning is finished via AGLBCE block. But you need to tune GDRC by setting the alpha blending to 256 first and then tune LDRC by setting the alpha blending to 0.

The meaning of each parameter is captured in the user guide.

[yancheng]

Thanks for the steps. BTW, how to understand every value of the table below from Live Control-METADATA? 

[yipingwang]

Please refer to the following update from the AE team.

These values are used for our Tuning Tool vendor to do internal debug. Please ignore them and we will document the information in the future.

[yancheng]

Still hope to parse the 2 info parameters which can map different wdr scene. thanks~

[yipingwang]

Please refer to the following update from the AE team.

I understand it is better to interpret every parameter. However, the information is not open to nxp either.

[yipingwang]

OK, thanks, will report your requirement to the AE team.

[yancheng]

Any update about the two info data?