RGBa image from intel realsense to matlab

Question

I'm trying to send a frame from the intel realsense camera to matlab. dDisplaying the image by imshow(...) or image(...) didn't make the job since the image is an rgba image... I have sent the image as an object from C# :

matlab.Feval("getImage", 1, out result, bitmap_data);

Is there a function that can display the frame ?

Answer 1

You will have to play with the exact Feval implementation, but if you were to impelment it directly in matlab there are two options

1.Simply ignore the alpha channel

%this says show all rows, all cols, for channels 1 through 3 or R,G,B
imshow(rgba_im(:,:,1:3));

2.Use the alpha channel

%this says show all rows, all cols, for channels 1 through 3 or R,G,B
%also saves the handle to the newly drawn image
hndl = imshow(rgba_im(:,:,1:3));

%isolates alpha channel
alpha = rgba_im(:,:,4);

%displays alpha channel
set(hndl , 'AlphaData', alpha);

EDIT

Now that I know your data isn't in the standard rgba format here is the code to fix it, the comments should tell you everything you need

[num_rows,num_cols_x4]=size(rgba_matrix);

%we have to transpose the array to get it to unfold properly, which is
%first by columns, then rows
at = rgba_matrix.';

%converts data from [r1 g1 b1 a1 r2 g2 b2 a2 r3 g3 b3 a3....] to 
% red_chan   = [r1 r2 r3...]
% green_chan = [g1 g2 g3...]
% blue_chan  = [b1 b2 b3...]
% alpha_chan = [a1 a2 a3...] 
% it says start at some index and grab every 4th element till the end of the
% matrix
red_chan = at(1:4:end);
grn_chan = at(2:4:end);
blu_chan = at(3:4:end);
alp_chan = at(4:4:end);

% reshape each channel from one long vector into a num_rows x (num_cols_x4/4)
red_chan = reshape(red_chan, num_cols_x4/4, num_rows).';
grn_chan = reshape(grn_chan, num_cols_x4/4, num_rows).';
blu_chan = reshape(blu_chan, num_cols_x4/4, num_rows).';
alp_chan = reshape(alp_chan, num_cols_x4/4, num_rows).';

% we concatenate the channels into a num_rows x (num_cols_x4/4) x 4 matrix
standard_rgba = cat(3,red_chan,grn_chan,blu_chan,alp_chan);

From this point you can do the processing I suggested using the standard_rgba array. There may be a more efficient way to write this code, but I wanted to make it as clear and easy to follow as possible, hope this helps