How to publish image to ROS in Simulink

I use the function writeImage() in matlab function to write a MATLAB image to the ROS image message，but when I run the simulink model, an error appears: Undefined function or variable 'writeImage'. How to solve this problem? How to publish image to ROS in Simulink?

Answer 1

[JAI PRAKASH]

If your matlab image is 'RGB' matrix, you can use following matlab function block + Bus assignment block as shown in figure.

function [H, W, Enc, EncLength, IsBig, Step, Data, DataLength] = fcn(im)
  [H, W, n] = size(im);
  H =uint32(H); W =uint32(W);
  im = permute(im,[2 1 3]);
  Data1 = im(:);
  Data2 = reshape(Data1,[H*W,n])';
  Data = Data2(:);
  Enc = zeros(1,128, 'uint8');
  Enc(1:4) = uint8('rgb8'); %   uint8('rgb8')
  EncLength = uint32(4);
  IsBig = uint8(0);
  Step = uint32(W*n);
  DataLength = uint32(H*W*n);

See the attached simulink readymade block also to convert MAT image to ros image message.

[snow John]

Help please！I got this error below：

Inferred size ('scalar') for data 'Data' does not match back propagated size ('[556416]') from Simulink.

Component:MATLAB Function | Category:Coder errorOpen

Simulink cannot determine sizes and/or types of the outputs for block 'PubImage1/Data to fill me Blank msg' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.

Component:MATLAB Function | Category:Coder error

Simulink cannot determine sizes and/or types of the outputs for block 'PubImage1/Data to fill me Blank msg' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.

What should i do？

[Pavan Anandareddy]

Hi,

Were you able to solve this error?

[Syed Adil Ahmed]

For those interested you can fix the non matching size of the Data bus variable by changing array sizes in Simulink for ros. This option is under tools> ROS in simulink.