How to get 10-bit depth black and white image from raspicam v2.1?

Question

I am a little bit confused about image capturing by Raspberry pi camera V2.1 [1]. I work on the Raspberry pi 4 and I know how to get 8-bit depth black and white (BW) image from it on the C++ level with e.g. raspicam library [2] - so the images pixel values are in the range 0-255. But in the product description and many others shopping descriptions, we can find that this camera based on SONY IMX219 sensor [3] is able to capture 10-bit depth raw image (also it is mentioned in the [1]) - so in range 0-1023. How to achieve such depth of image? Best scenario is to get it on the C++ level, without OpenCV, but after few days of searching I can deal with any kind of information about it ;) . Maybe there is different camera with similar parameters to above, but with higher than 8-bit depth in default?

All the best.

[1] https://www.raspberrypi.org/documentation/hardware/camera/

[2] https://github.com/cedricve/raspicam

[3] https://botland.com.pl/index.php?controller=attachment&id_attachment=1950

Answer 1

From picamera.readthedocs.io, 5.11. Raw Bayer data captures :

Bayer data consists of 10-bit values, because this is the sensitivity of the OV5647 sensor used by the Pi’s camera. The 10-bit values are organized as 4 8-bit values, followed by the low-order 2-bits of the 4 values packed into a fifth byte.

You can read this code for an example of raw datas extraction from raspistill raw capture.