Python Convert 12 Bit Image Encoded In A String To 8 Bit Png

I have a string that is read from a usb apogee camera that is a 12-bit grayscale image with the 12-bits each occupying the lowest 12 bits of 16-bits words. I want to create a 8-bi

Solution 1:

Wump's comment about converting an image gave me an idea, and I did it by

#shifts by 4 bits and converts to 8-bit imageimg = img.point(lambda i: i * 16, "L") 

Thanks Wump

Solution 2:

The only way I know how to do it would be:

data = numpy.fromstring(imageStr, numpy.uint16)
data >>= 4 # shift out four bits
data = numpy.array(data, dtype=numpy.uint8)
img = Image.fromarray(data.reshape(imageSize))

In principe, PIL can convert images this way:

img = img.convert("L")

But the problem is that it has no way to reduce the precision to 8 bits (AFAIK), so everything will be clipped to 255 :)

Edit: removed intermediate string conversion, it's going directly from numpy to PIL now