How do I generate code for 'rectifyStereoImages' functionality to rectify stereo camera images?

I have 2 images ('img1' and 'img2'), and have a variable called 'stereoParameters' that contains the Stereo Parameters. that I have generated by calibrating my stereo camera.

https://www.mathworks.com/help/vision/ref/stereoparameters.html

I run the following function without a problem:

>> [J1,J2] = rectifyStereoImages(img1,img2,stereoParameters)

I would like to generate C code for the same. When I tried to generate code with the 'codegen' function, I keep getting the following error:

>> codegen rectifyStereoImages -args {coder.typeof(img1), coder.typeof(img2), coder.typeof(stereoParameters)}; 
??? Not enough input arguments. Error in ==> rectifyStereoImages Line: 112 Column: 5 Code generation failed: View Error Report Error using codegen

Why do I see this error? How do I generate code that can rectify images?

Answer 1

[MathWorks Support Team]

MATLAB coder does not support the passing of the 'stereoParameters' object as an argument into a function. I recommend you pass the information in as a struct, and then create the 'stereoParameters' object inside the function, as suggested in the link below:

https://www.mathworks.com/help/vision/ref/rectifystereoimages.html#bvmuj0w-1

The workflow is to:

1) Set up a function that accepts structs as an argument, and generates the 'stereoParams' within.

2) You can then pass this generated 'stereoParams' into the rectifyStereoImages function.

3) I also recommend setting up the 'stereoParams' to be a persistent variable, so it is not generated with each instance of the function being called:

https://www.mathworks.com/help/matlab/ref/persistent.html

Thus , please create the following function:

% Input Arguments would be image matrices and a struct
function [a,b]= img_rec(img1,img2,stereoParamStruct)
    persistent stereoParams
    if isempty(stereoParams)
        % Create the stereoParams object using the input struct
        stereoParams = stereoParameters(stereoParamStruct);
    end

      % Now that the object is created, you can run 'rectifyStereoImages'
          [a,b]=rectifyStereoImages(img1, img2, stereoParams);
  end

You can use the commands listed below at the MATLAB command prompt to generate embeddable code.

>> params_str = toStruct(stereoParameters)
>> codegen img_rec -args {coder.typeof(img1), coder.typeof(img2), coder.typeof(params_str)};