RTOS/TDA3XEVM: TDA3X Tuning in low light.

Hi Blessy,

I have forwarded your question to Imaging experts.

Regards,
Yordan

Hi,

We would like to get the help from MM solutions regarding the HDR. How can i proceed forward?

Hi,

Any update on the enquiry?

We are trying to control the exposure to handle the headlight issue. We are trying to reduce the gain when the headlight falls on the camera but we are experience some blink issues. We are getting a gain of 0 and then it is suddenly jumping to some high value like 192, so we are not able to decide a cut-off. Do you think whether there is any hope proceeding with the exposure control like this?

We are having another idea of including the exposure metering table.
Can we solve this issue if we have a good exposure metering technique? Currently is there any algorithm (metering matrix) that is existing in our visionSDK? Which file should we exactly look into for exposure control?

Can you please help me with this.

Hi Mayank,

This headlight issue happens when the vehicle is at a distance about 5 meters away from the camera and light not directly falls on camera. So in frame the headlight will look spread as the camera exposure value is high (as no light falls directly on camera it will be exposed more).

Is this due to missing a proper exposure table or exposure metering technique ? We hope this issue can be solved if there is a better exposure metering technique. Is there any metering algorithms or table implemented in SDK for auto-exposure ? Where we need to exactly look into for this ?

• vision_sdk/apps/src/rtos/iss/src/alg_plugins/iss_aewb/src/ae_ti.c :- Is this the file which handle statistics of frames to do exposure control ?

Hi Mayank,

Thanks for your reply !!!

We hope the highlight in frame not suppressed with auto exposure algorithm alone; as it is missing a proper metering technique. We will try to define a weight matrix and implement a metering technique as you suggested. How can we to select the weight matrix ? Is it a 20x20 matrix or 50x8 matrix ? aew_win_hz_cnt = 20 and aew_win_vt_cnt value = 20. 

Also another issue is like we can not exactly find out the headlight scenario. Thats why we asked about exposure metering technique.

Blink issue we noticed when we tried to manually adjust gain to minimum value for highlight condition ie, like set gain writing to register made as zero. During this time we can notice blink in video as exposure is not settled. It is changing between min gain for headlight condition (say 0) and normal exposure values calculated from AEC algorithm.

Now the gain values written to sensor register are  "0, 192, 213, 234, 255" for different combinations of line count. These gain values/gain table is calculated corresponding to the analog gain values like 1000, 2500, 5000, 10000, 20000 updated in "pAewbAlgOut->outPrms[0].analogGain" in vision_sdk/apps/src/rtos/iss/src/common/app_util_iss.c . Can you just detail how to change these exposure table and and gain table values to get little more smooth gain steps or a better gain table with small step size ?

Hi Mayank,

Any updates regarding our queries ?

• AE metering by adding a weight matrix ? 
• How to change exposure table and gain table for better exposure control ? In DCC tool, there is no options to do exposure tuning.  

We are working on adding a weight matrix for AE metering. We are able to notice changes in headlight when we add same weight (say weight = 2)
for all rbgData[0] to rgbData[399]. Can you just tell how these 400 samples are taken from a frame ? So that we can give different weight to different samples (more weight to center of frame) to handle headlight.

Ok. 

Any user guides available to familiarize TI's Auto exposure algorithm on TDA3x (Use case is rear view panorama) ? 

Hi,

We tried to add a weight matrix (20x20) with RGB data (20x20) in GETTING_RGB_BLOCK_VALUE function (algTIaewb.c). We noticed some color banding in video and it increases with increasing weight value.  What can be the reason for this color banding issue ? Is there any limitation on this maximum value of weight that we can apply ?

In algTIaewb.c, a function "Init2ATables()" define a weightingMatrix like assigning value of 1 to all 400 samples.

ie; pObj->weightingMatrix[i*width + j] = 1;

This weighting Matrix is then passed to TI's AEC algorithm inside ae_ti.c file. What is this values exactly ? Do we need to change weight matrix here? There is a comment here like "Set all weights to 1 to avoid overflows. Center and Spot Metering disabled till Overflow issue is fixed".

Color banding looks like the below image. 

Hi,

Any updates ?