How to get correct intensity of an image taken under 12-bit but in RGB mode?

I use a high speed camera to take pictures in my test, and all pictures taken by this camera look gray, without other colors except black and white.

The camera takes the pictures in 12-bit, however in the monitor screen it is indicated that the image is being taken in RGB mode.

As I use 'imread' to get the intensity information of the pixels that compose the image, it indicates that most of the pixels' intensity values are 255.(for 8 bit images, the intensity range should be 0~255).

So obviously, the intensity value I got is not correct and should be larger than those I got.

I need to do something on the taken images to get the correct intensity, but I don't know how.

[zy]

For your information, by using 'imread', the matrix format is 1280x800 uint8.

While for real RGB mode images, it should be 1280x800x3 uint8.

[zy]

If I try to add an value of 3041 to each cell of the array, all cells would only be changed to 255.

It seems that the upper limit for the value of each cell is limited to 255.