Lab05: Parallel Computer Vision Processing

Objective
To "parallelize" a C program that shifts an image a to the right or left a certain number of pixels.
download pgmReader.c, a C program that reads a "PGM" image file.

--Sample PGM image files:

image1.pgm, an 8 pixel by 8 pixel image of a pattern.
widget.pgm, a 12 pixel (rows) by 15 pixel (columns) image of a pattern.
fig1.pgm, a 128 pixel (rows) by 97 pixel (columns) image of a camera tripod.

Background material on PGM image files (these are uncompressed ASCII files
containing numbers representing pixel values):
Explanation of PGM and PPM image file format

Viewing an image file with "xv".

Type "xv &" on the command line, this loads "XV by John Bradley"
Right click on this XV image. This should bring up the menu "xv controls"
Load "fig1.pgm". This is a 128 pixels (rows) by 97 pixels (cols) image of a camera tripod (black and white)
Load "widget.pgm". This is a very small image, 12 pixels (rows) by 15 pixels (cols).
In order to see the image, increase its size by dragging the corner with your mouse.

Assignment

Become familiar with "pgmReader.c" and image files
--Read an image file (a ".pgm" file) and write the pixel data to "newPic.pgm"
--With vi, view newPic.pgm
Modify pgmReader.c so that it reads the image file and shifts the image
a certain number of pixels to the right.
For example, shift the image of the tripod 25 pixels to the right.
Next, write a version to shift the image to the left.
Save each transformed image and display on your website portfolio
Describe your algorithm - how did you shift the image?
Use MPI_Wtime() to analyze the efficiency of using various numbers of processes.