Re: Dealing with MONO12 images in memory

On Tue, 21 Nov 2017, Robert H. Olsen wrote:

>
> Thank you very much for your quick reply Bob.
> This works very well when I limit the camera to MONO_8 images.  I am still 
> having trouble with the 12 bit images, but I need to verify my own code (I 
> may have may some mistakes refactoring to use GraphicsMagick)  before I 
> assume the problem is with how I am calling your functions.

The gray coder does not appear to support 12 bit images since the C 
API supports obtaining a sub-rectangle of the image, which requires 
random access.  Random access is most easily done with pixels aligned 
with bytes.  The gray coder can support 8/16/32 bit images.

Are your 12-bit images a compact stream of bits (e.g. in big-endian 
order with samples crossing byte boundaries), or are they 12-bits in 
16-bit samples, or something else?  One possible way to know is if the 
(rows * columns * depth) / 8 ~= data size.

If you do have compacted 12-bit data, do not lose hope since there is 
always Plan B.

> Can you tell me where I can find the options for that final argument "GRAY" 
> in the image.read() function?  I tried calling
>  ListMagickInfo_L("ListMagickInfoResult");
> which looked like it might give me that sort of information, but I probably 
> either made a mistake in linking or scoping (or...) since I got a message 
> that the function couldn't be found.

From the command line, one can learn the supported formats via:

   gm convert -list formats

The ListMagickInfo() function writes the same output to a C file 
handle as produced using fopen().

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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