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

[Peter Griffin]

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>

regards,

Peter.