Calling MATLAB functions in Visual Basic

I made a very simple program to try how to call matlab functions in visual basic. My matlab program is this:

function showRGB()
origImage = imread('imagefromvisualbasic.jpg');
redChannel = origImage(:,:,1);
greenChannel = origImage(:,:,2);
blueChannel = origImage(:,:,3);
end

Here's the GUI of the app made in vb.

I've tried reading this help and here's the code of the vb.

1. How will I use the imread in matlab to read the image from the openDialogBox of VB?

2. How will I use access the output from MATLAB to show the RGB Channels in the picture box?

Thank you

Answer 1

[Friedrich]

Hi,

1. you can't. You would need to send over the RGB image data from VB to MATLAB, e.g. by using the PutWorkspaceData method
2. the way you have desgined your function you can't. You would need to make the RGB channels output variables

function [redChannel ,greenChannel,redChannel] =  showRGB()

and then call the Execute method

ml.Execute("[a,b,c] = showRGB()")

to create the variables a, b and c in the base workspace which you then can get to VB by calling GetWorkspaceData. The example you mentioned does all that.

[Elvin]

Thank you very much for the help. I tried fixing my codes but I got an error when running it. here's the new matlab code:

function [redChannel,greenChannel,blueChannel] =  showRGB(inputImage)
RGBImage = imread(inputImage);
redChannel = RGBImage(:,:,1);
greenChannel = RGBImage(:,:,2);
blueChannel = RGBImage(:,:,3);
end

Here's the VB program:

Thanks again for the help. Sorry, but I'm not that good in visual basic.

[Friedrich]

Hi,

i doubt that the conversion from tghe VB type Image to something MATLAB can use is done automatically. YOu need to convert that by your self. Basically the data converion rules from here

web([docroot '/matlab/matlab_external/handling-com-data-in-matlab-software.html'])

apply. BTW: what does the MATLAB side receive when your try to put the Image data type to the MATLAB workspace?

[Elvin]

I'm still confused with this one. Is there any easier method to do this?

By the way, when I run the program using the upload button, nothing is happening in the matlab. No variable was sent to the workspace. But the matlab command windows is popping up.

By the way, is there a way to compile my matlab code so I can use it in visual basic in such a way that a pc without matlab can still run the program?

[Friedrich]

I doubt there is an easier way.

You could compile your MATLAB Code with MATLAB Builder NE in order to generate a COM component out of it. You could then use that back in VB. However this wouldn't solve the Image datatype conversion. You would still need to do this on your own.

[Elvin]

Can you show me a sample? I'm really confused with this one.

[Friedrich]

I am not really VB programmer but I guess you have to call the save method and save the image into a stream. As a stream use some byte array. I guess googling for that task should give some hints.