SIMULINK and Image and Video Processing Blockset prepared by Wei Du 07/2007 Rev. 1.1 by Justus Piater 11/2007 University of Liège
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SIMULINK andImage and Video Processing
Blockset
prepared by Wei Du 07/2007Rev. 1.1 by Justus Piater 11/2007
University of Liège
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Contents
Tired of writing MATLAB code? Let’s try something different: build a system by assembling blocks!
– SIMULINK
– Image and Video Processing (IVP) Blockset
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What is SIMULINK?
A platform for building and simulating models
Integrated with MATLAB and toolboxes
Graphical editing: block diagram– Can drag and drop blocks
Extensive libraries of blocks available
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Structure of SIMULINK Model
A typical SIMULINK model includes sources, systems and sinks.
sources sinks
To disk filesTo display
To Matlab workspace
systems
From disk filesFrom Matlab workspace
Interconnections of blocks
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Model example
system
sourcesink
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Basic element -- Block
A block is an operator in a black box!
Blocks are connected by directed lines, passing along the signals.
block
input signals output signals
>
Input ports
>
Output ports
>>
>
outp
ut o
f oth
er b
locks
input o
f oth
er b
locks
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Basic Blocks
Math operation: sum, product, gain, …
Logic and Bit operations: and, or, …
Signal Routing: Selector, …
Commonly Used Blocks: integrator, delay, data type conversion, …
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Source and Sink Blocks
Source: blocks without input ports– constant, sine function, random, file
loader, …
Sink: blocks without output ports– display, file saver, …
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Signals
Data type - single, double, signed or unsigned 8-, 16-, or 32-bit integers; fixed-point; and Boolean
Dimensions - scalar, vector, or matrix
Watch out: make sure the signal attributes match!
block1> >
>
>
block2>>
>
signals
signalssignals
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How many blocks do we have?
Standard SIMULINK libraries– More than 200 built-in blocks
Blocksets: more than 10– Image and Video Processing– Signal Processing– …
User defined libraries– M-function, S-function
Blockset
Libraries
Blocks
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Build a model step by step
system
sourcesink
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Build a model step by step(1)
Launch SIMULINK and create a new model
– Click SIMULINK button– Type in “simulink” in matlab command
window
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Build a model step by step(2)
Find all the necessary blocks
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Build a model step by step(3)
Connect blocks
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Build a model step by step(4)
Adjust the layout
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Build a model step by step(5)
Change the labels and add annotations
Input Signal
Original Signal
Filtered SignalAmplify
Gain You can add text annotations anywhere you want
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Build a model step by step(5)
Ctrl-T, Run!
Input Signal
Original Signal
Filtered SignalAmplify
Gain You can add text annotations anywhere you want
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More SIMULINK basics
Double-click on a block to open its Dialog Box. Parameters for the block can be set in this box.
Click on the HELP button on the Dialog Box of a block to launch the HELP file for the block.
You can rotate, flip or resize a block. Useful to create a more readable block diagram.
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Subsystems
Select portions of the model using the mouse and turn them into a subsystem.
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A real problem
Given a rectangle box = [r,c,h,w], compute the center mid = [cx,cy] of the rectangle.
c
r
h
w
*
O
[ r, c, h, w ]
*
O
Row
Column X
Ymatrix coordinate image coordinate
cy
cx
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Matlab Implementation
function mid = Box2Center(box)
r = box(1); c = box(2); h = box(3); w = box(4);cy = r+h/2;cx = c+w/2;mid = [cx,cy];return
How to do it with SIMULINK?
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Simulink Implementation(1)
Select elements from a vector.
–r = box(1); c = box(2); h = box(3); w = box(4);
–Selector Block
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Simulink Implementation(2)
Sum and Divide
– cy = r+h/2; cx = c+w/2;
– Sum and Gain/Divide Block
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Simulink Implementation(2)
Combine elements into vector.
– mid = [cx,cy]
– Concatenation Block
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Does it work?
Test: add source and sink.– Constant– Display
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Image and Video Processing(IVP) Blockset
A set of blocks that do image and video processing.
– Access image and video files– Filtering– Morphology– Edge detection– Geometric transform– Text and graphics– …
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A real problem
Convert RGB images to gray-scale.– Source: Image or Video Loader– Sink: Image or Video Viewer– System: Add and Gain blocks
Watch out: data types of signals must match!
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A real problem
Draw rectangles in an image, and plot a marker at the center of each rectangle.
– Source: Image or Video Loader and Constant
– Sink: Image or Video viewer– Box2Center– Text and graphics blocks
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That’s all!
Have fun in the lab! – Get familiar with SIMULINK and IVP
blockset.
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