Passing byte array from c# .net to matlab

I have a byte array (image data in 1024 x 1024) that I want to pass back to Matlab.

My C# is returning data as follows:

          public byte[,] frameBits(int id)
          {
              return ((Frame)frames[id]).frameData;
          }

it appears in matlab as

    Name      Size            Bytes  Class             Attributes

    f         1x1               112  System.Byte[,]

if I do a uint8(f); then f is:

    g         1024x1024            1048576  uint8

which sounds right, but the image with imshow(is only a small section from the middle, and it is a mirror image).