[libcamera-devel] [PATCH v1 0/6] IPA RkISP1 awb and misc improvements

[Jean-Michel Hautbois]

Hi Peter !

On 24/01/2022 17:50, Peter Griffin wrote:
> Hi Jean-Michel,
> 
> On Thu, 02 Dec 2021, Jean-Michel Hautbois wrote:
> 
>> Hello,
>>
>> This series introduces several algorithms or tuning parameters for the
>> RkISP1 IPA.
>>
>> First, the imx219 is a non linear CMOS sensor and its channels are
>> compressed. In order to have a better exposed output frame, we need to
>> apply a deGamma curve on the raw pixels, which is done by a simple
>> look-up table on the ISP side. The values are taken from the imx219.json
>> tuning file in the RPi IPA.
>>
>> The next algorithm is the black level correction. The output is washed
>> out if no black correction is applied. Again, use the tuning values from
>> the imx219 data file in RPi.
>>
>> Now, we can estimate the AWB gains to apply on the red and blue
>> channels. The RkISP1 could theoretically give us the red, green and blue
>> mean values for the current frame, but the kernel seems to lack support
>> for this. Use the YCrCb estimation instead, and convert the values to
>> RGB before estimating the gains. We don't have a grid of average values,
>> only a global mean for each channel.
>>
>> Next, the color correction matric needs to be a bit modified as the
>> default one is a simple identity matrix. A very simple estimation uses
>> the red and blue gains calculated but a real tuning file would be
>> better, based on color temperature as the imx219 data file.
>>
>> Last patch introduces the histogram IQ mean estimation as for the IPU3
>> and uses the maximum of the relative luminance gain and the iqMean gain
>> to determine the shutter speed and analogue gain to apply.
>>
>> I wanted to post captured images for each of those algorithm to see the
>> evolution but I accidentaly broke my sd card connector... and I am now
>> stuck until I can repair it... :-(
> 
> I tested this series on my RockPi4b with Sony IMX219, and the image quality looks
> much better :)
> 
> I didn't take captured images after each algorithm, but I did do some captures
> before this series was applied, and after. The captures can be found here:
> 
> https://people.linaro.org/~peter.griffin/rkisp1captures/
> 
> I have been using ffplay to view them with the following command
> 
> ffplay -loglevel warning -v info -f rawvideo -pixel_format nv12 -video_size
> "3280x2464" cam0-stream0-000009
> 
> FWIW for the series:
> 
> Tested-by: Peter Griffin <peter.griffin at linaro.org>

Thanks for testing !
In order to ease the viewing here are the 9th frame without 3A:
https://pasteboard.co/RVvX1N5XBHeY.png

And with 3A:
https://pasteboard.co/Eav971LRIN3I.png

JM

> 
> regards,
> 
> Peter.