Thread Subject: Load picture in a Simulink (2lvl Mathlab Fcn) block

Hey there,

I guess my biggest Problem is that I am a total Simulink novice. For the last week I am trying to read an image in a Simulink block. First, I thought I just create an embedded Matlab function using the "imread" command like it is possible in Matlab. But this is not working in Simulink.
I also don t have the Video and Image Processing Blockset (so no "read image from file" block), but I guess that is exactly what I am searching for.

In S-Function Examples (see User-defined Functions) there is an example on how to load a video from a .mat-file in a block. I have tried to modify this block to fit my purpose, no success.

I would be grateful for any advice
Marcus

Did you define imread to be eml.extrinsic?

Phil.

"Phil Goddard" <phil@modeling-simulation-visualization.com> wrote in message <jc7e7c$k3t$1@newscl01ah.mathworks.com>...
> Did you define imread to be eml.extrinsic?
>
> Phil.

Are u referring to me using a "Matlab embedded Fcn"- Block and then "evaluating" the imread command?

Marcus

Yes.

Phil.

Try this page:

http://www.mathworks.com/help/toolbox/simulink/ug/bsoywg7.html

and search for "extrinsic" within this page.

Witek

Marcus <m.futterlieb@tu-bs.de> wrote:
> "Phil Goddard" <phil@modeling-simulation-visualization.com> wrote in message <jc7e7c$k3t$1@newscl01ah.mathworks.com>...
> > Did you define imread to be eml.extrinsic?
> >
> > Phil.
>
> Are u referring to me using a "Matlab embedded Fcn"- Block and then "evaluating" the imread command?
>
> Marcus

"Phil Goddard" <phil@modeling-simulation-visualization.com> wrote in message <jc7h54$sh0$1@newscl01ah.mathworks.com>...
> Yes.
>
> Phil.

Hey Phil,

so this is what i got:
%------------------------------------------------Matlab embedded fcn block---

function y = fcn(u)
%#eml


x = 'imread(''test.jpg'',''jpg'')';
eml.extrinsic('eval');
a = eval (x);


y = u*a;

%----------------------------------------------------------------------------------------

u is just a constant (1) and I would like to output the picture through y but Matlab is giving me this error:
***Function output 'y' cannot be of MATLAB type***
So does this will never work? Or am I missing something?

Thanks Phil, and Witek, I ll have a look at your link right now
Marcus

I'm not sure why you wouldn't just do

eml.extrinsic('imread');
y = u*imread('test.jpg','jpg');

But that's not likely the cause of the problem.

I suspect the issue is that you haven't preallocated the size of y and hence the code won't compile.
If you know in advance the size of the output then you can put something like zeros(n,m) at the top to do the preallocation.
If not, then you'll need to define the output as being variable sized:
http://www.mathworks.com.au/help/toolbox/simulink/ug/br9_55w.html

Phil.

"Phil Goddard" <phil@modeling-simulation-visualization.com> wrote in message <jc9ht0$q15$1@newscl01ah.mathworks.com>...
> I'm not sure why you wouldn't just do
>
> eml.extrinsic('imread');
> y = u*imread('test.jpg','jpg');
>
> But that's not likely the cause of the problem.
>
> I suspect the issue is that you haven't preallocated the size of y and hence the code won't compile.
> If you know in advance the size of the output then you can put something like zeros(n,m) at the top to do the preallocation.
> If not, then you'll need to define the output as being variable sized:
> http://www.mathworks.com.au/help/toolbox/simulink/ug/br9_55w.html
>
> Phil.

Alright guys,

It is working now, thanks for the help, if anyone is interested this is what I did:

***for the load function block I deleted the input and set the size for the output to [256 256] (right click the block and go to explore) uint8 (grayscale picture).
--------------------------------------------------------------------------------------------------
function y =load
%#eml

x = 'imread(''test.jpg'',''jpg'')';
eml.extrinsic('eval');
y=zeros(256,256,'uint8');
y = eval (x);
---------------------------------------------------------------------------------------------------

***for the display function block I deleted the output and set the size for the input to [256 256] uint8
--------------------------------------------------------------------------------------------------
function display(u)
%#eml
eml.extrinsic('imshow');
imshow(u)
---------------------------------------------------------------------------------------------------

Thanks again for the help :)
Marcus