Capture Image -- Color Format Conversion in ISI on imx8mp

[tamo2]

Hi, 

I just found that in AN13430 i.MX 8MP Dual ISI channels for single CSI it says that Color Space Conversion (CSC) can be done in ISI.

I was assuming that the color format conversion is done by ISP but it sounds like it can be done by ISI too. Our system based on imx8mp supports multiple sensors, such as Sony imx219, which output Bayer pattern.  We are planning to use ISP to get NV12 output.  But would it be possible to use just ISI instead of ISP?  Could you give me examples on how to do it?

Thanks!

[malik_cisse]

 find some pointers and code here:
https://community.nxp.com/t5/i-MX-Processors/Creating-a-MIPI-CSI-Camera-driver-on-i-MX-8MP-EVK/m-p/1...
https://community.nxp.com/t5/i-MX-Processors/Integrating-MIPI-CSI-camera-in-IMX8MP-processor/m-p/145...

[malik_cisse · Accepted solution]

Hi Tamo,

No! It is not possible to do Bayer to NV12 color conversion in imx8mp ISI.
The reason is simple: There is no debayering logic in the ISI. Only imx8mp embedded ISP features a debayer. 

When it says ISI has CSC, this is only simple conversion like YUYV to NV12 or so where only simple pixel operations are performed.
Debayering is the core algorithm of ISP.

What prevents you from using ISP? There are lots of examples and code even for imx219.

I hope this helps

[tamo2]

Hi malik_cisse, 

Thanks for the clarification!  

What prevents you from using ISP? There are lots of examples and code even for imx219.

As far as I know, you need to modify the driver (i.e. imx219.ko) to make it work with the ISP.  We support tens of cameras so porting all the sensor drivers to ISP is not very easy (but possible).

I have seen a few porting guides from NXP and a few examples such as Basler camera, but can you please point me to the imx219 example?

Thanks!