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Image Manipulation in MATLAB


30 min.
Objectives:
At the end of this practical you should be able to:
- understand the image concept
- read images into MATLAB
- display images
- generate histograms of regions of interest

Terminology:


See:
Grey Levels
Histogram
Pixels
Region of Interest
Read the introductory sections in the MATLAB user guide regarding file I/O and displays. Familiarise yourself with the MATLAB "HELP" facility.

We have prepared some short macro files which can be used for basic image display and region based histogramming which you should download and save as MATLAB .m files. They are
- pgmread(file) - Loads a .pgm image from file.
- my_disp(x) - display array x as an image.
- roihist - display display histogram from ROI.
and draw the histogram.
These should be placed in your working directory so that they can be executed in MATLAB.

Down load the images from this page as ".pgm" files and load them into MATLAB as arrays.

Practice drawing regions of interest and understanding the resulting data in the histogram.

Finally, using the histogramming routine as a starting point, attempt to write your own MATLAB routine which allows you to plot the grey levels along a selected line. You will need to be able to use this method in later practicals as an investigative tool.



(c) Imaging Science and Biomedical Engineering 2000 [paul.bromiley@man.ac.uk]

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