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Using TI 2A to control gain only

Eli Balta
Intellectual 935 points


Currently I'm using the TI 2A algorithm for AEWB.

For my application, I wish to use a fixed, manually set value for sensor exposure, but I'd like to still make use of the AGC engine that TI 2A provides.

So far the only solution I thought of is simply ignoring the first bit of ti2a_output_params.mask in the sensor driver, and adjusting only gain parameters. However, this seems like an ugly workaround since the 2A engine is still going to "think" exposure has been adjusted.

Is there any way to disable automatic exposure control in the algorithm itself and stay only with gain control?

  • 0
    TI__Expert 8780 points

    Eli,

    Which software version are you using?

    in the IPNC codebase AE is released in source code, so you will need to understand the code and make necessary changes if you only want to control the gain.

    Can I ask how do you plan on controlling exposure?

    Typically exposure and gain should be controlled by same compute function since they are finally inter-related in terms of image quality.

    Regards

    Rajat

  • 0 in reply to Rajat Sagar
    Intellectual 935 points

    Hi Rajat,

    I am using IPNC RDK 3.5

    Our application requires manual exposure control. When this option is picked, I wish that only gain will be automatically controlled by 2A algorithm.

    I am familiar with the following file:

    Source/ti_tools/iss_03_80_00_00/packages/ti/psp/iss/drivers/alg/2A/src/issdrv_algTIaewb.c

    is this the source code you're referring to?

    Another option I thought about is setting both of the following parameters:

    gTi2aControlParams.minExposure
    gTi2aControlParams.maxExposure

    to the manually chosen exposure value when manual exposure control is used. I will try implementing this and see if it causes any problems.

  • 0 in reply to Eli Balta
    TI__Expert 8780 points

    I think controlling following - 

    gTi2aControlParams.minExposure
    gTi2aControlParams.maxExposure

    will be better. Please try and let us know if you still need more modifications.

    Regards

    Rajat

  • 0 in reply to Eli Balta
    Genius 4405 points
    Hi Eli,
    Did this work?
    We've come across another interesting problem - maybe you have some idea.
    Using the 10Mp sensor (MT9J003), when I use less than 3600 pixels width (1800 pixels with binning), the AGC/AWB of the 2A engine stop working.
    I'm trying to figure out where in the 2A code I can change this behaviour.
    Any ideas?
    Thanks and Regards,
    Mechi
  • 0 in reply to Mechi Fendel
    Genius 4405 points
    When we lowered the minExposure to 100 (10us), the AGC worked well in very lit, outdoor places. The bug was that the IPNC had the minExposure set to 5ms!

    Hope this helps,
    Mechi