Problems with using mxarrays with the step function in MATLAB Coder

I'm trying to convert my image processing code on MATLAB into C by using MATLAB coder. using 'imread' needs a coder.entrinsic declaration. However, this means that the output to imread will be an mxArray. This is a problem as I cannot use this with the step function. The error report from code generation is shown below:

Does anyone know a way around this? Help will be very much appreciated!

Answer 1

[Sharan Duggirala]

The answer has been found here for anyone wondering about it.

Thank you for your help!

Answer 2

[Ketan]

You can assign the output of the extrinsically called imread to a variable of known type. For example:

% Assume IMREAD output is real uint8 [480 x 640]
I = zeros([480,640],'uint8');
I = imread(...);

Then it will not be treated as an mxArray which can only be used in a limited set of circumstances. See the following documentation for information on converting mxArrays to known types:

http://www.mathworks.com/help/coder/ug/calling-matlab-functions.html

[Sharan Duggirala]

I have a variable input to this function and it tells me that coder.varsize cannot be used with coder.entrinsic.