NetPBM Image Format Exercises

1
NetPBM Image Format Exercises

• http//netpbm.sourceforge.net/README

2
Creating Sample NetPBM images

• Using the examples in the NetPBM man pages for
  pbm, pgm, and ppm
• Use a text editor to create the corresponding
  sample images
• feep.pbm
• feep.pgm
• feep.ppm
• If you are unfamiliar with using any of the UNIX
  text editors, startup the tutorial on the CIS
  systems
• rvrpci/pub/vitutor/vitutor
• or check out
• http//ecn.www.ecn.purdue.edu/ECN/Documents/VI/
• http//www.ncsu.edu/it/pub/tutorials/pico_tutor/pi
  co.html
• Use the xv utility to display these sample images

3
Index Example

• Use the pnmindex routine
• make a single image catalog of the images
  feep.pbm, feep.pgm, feep.ppm

4
Rotate Example

• Taking the image feep.pbm you created
• Rotate the image counter clockwise using one of
  the NetPBM utilities

5
Flip Example

• Taking the image feep.pgm you created
• Flip the image

6
Cut example

• Taking the image feep.pgm
• Cut out the subimage shown below

7
Image Concatenation Example

• Taking the results from the previous slides
• Index, Rotate, Flip, Cut
• Concatenate the results of these processes into
  one image

8
Histogram Example

• Compute the histogram of feep.pgm and plot it
  using any UNIX plotting utility
• Normalize the feep.pgm and repeat the histogram
  plot
• Based on the output of pgmhist
• Come up with a strategy of how you might compute
  the following
• Min, max, sum, mean, variance, standard deviation
• Do not try to implement anything yet, simply
  state in a stepwise manner what needs to be done
• As we get exposed to other UNIX utilities, we
  will implement and write scripts that will
  compute these values.