CMP 161 -- Winter 2010

CMP 161 -- Programming Assignment 1

Due date:
Midnight, FRI, 1/29/2010

Objectives:

Learn about different uses of pseudo-coloring, Design/edit colormaps for various applications.

To Do:

Write a program with the following functionality:

Reads and displays an image in GIF format. You can use imagemagick format conversion utility to convert your favorite image to GIF format. You will need to write your own code to display the image -- each pixel is rendered as a quad. You probably want to scale the image to some reasonable window size while maintaining the aspect ratio of the image.
Note: There are two ways of reading in a gif file. 1) Find a gif file that will allow you to open a gif file and see the rgb values. 2) Use this perl script that will take in a gif file, test.gif and spit out two files, test.ppm and colorMap.txt. The perl script makes uses of the program ImageMagick, so in order for it to succeed, you will need to download ImageMagick. The best way to run the perl script is on your unix account.
Example: >perl getColorMap.pl test.gif ( approximately 10% )
In a separate window, display the histogram of pixel values. GIF uses an 8 bit index (0..255) into a color map. Your histogram should show the frequency of each index value. Color the frequency of each index value according to the color associated with the index. Position this display above the image display window, and make this the same width as the displayed image. ( approximately 10% )
In a separate window, display the color map (legend or palette) associated with the image. There should be 3 "curves": representing the red, green, and blue components. The x-axis is the index (i.e. pixel) value. The y-axis should range from 0..255 and plots the red, green, and blue component of the color associated with the index value. Position this display below the image display window, and make this the same width as the displayed image. ( approximately 10% )
Allow the user to "brighten" or "darken" the image. This is achieved by changing the RGB values associated with the pixel values. Each time the "brighten" or "darken" button is selected, the RGB values are increased or decreased by 10% (multiplied by 1.1 or 0.9). Round off and maintain color values to range from 0..255. Update images of histogram and color map. ( approximately 20% )
Allow the user to convert the color image to grayscale. This is achieved by changing the RGB values associated with the pixel values. When this option is selected, change the associated color value to: (g, g, g), where g = (0.30R + 0.59G + 0.11B)/255. Round off g to integer value between 0..255. Update images of histogram and color map. ( approximately 10% )
Allow the user to randomize the color mapping (palette). This is achieved by changing the RGB values associated with the pixel values. When the randomize button is selected, the RGB valus associated with the pixel value are randomized (maintain values in 0..255 range). Update images of histogram and color map. ( approximately 10% )
Allow the user to interactively edit the color map. (i) Users can change RGB values of an individual color index by picking and dragging the curves above the index up or down with the right mouse, or (ii) users can change entire curve segments by picking and dragging with the left mouse. A control point is added at the index value where the mouse is released. Linear interpolation is used. Each left mouse click will add a new control point. Constrain mouse movements between left and right neighboring control points so that curves are always functions i.e. unique y-value for each x-value. Update the image and histogram displays also. ( approximately 30% )
Bonus (20%): Allow the user to improve image contrast via histogram equalization. Note that unlike the previous requirements which maintains the pixel values but change the colors associated with the pixel values, histogram equalization will change the pixel values. Histogram equalization on grayscale images will only earn 10%. To get 20% bonus, you must be able to apply this process to color images by equalizing their luminence, while maintaining their hue and saturation.
Note that there are several description (and implementation) for histogram equalization. The following site is fairly easy to understand: codersource.net. Another site that may be helpful is: program hints.

Items To Submit:

A file called prog1.html with description and images of your project. Make sure your links are all local and relative to your submit directory. Call the submit directory prog1.
Include results (images) using the ramp test data.
Include results (images) using your favorite image. Include the your test image also. All of the above should be accessible from the prog1.html file.

Grading:

This program nominally accounts for 5% of your final grade. We must be able to compile/test your code. Make sure that code and accompanying make/project files, etc. must be tested for successful compilation at least on the PCs in the lab. Also be sure to include the executable and a README file in your submission as to which platform to use. Programs turned in at least a full day early will earn 1% bonus credit. Late programs will be charged 1% late points. In addition, late programs will not be accepted 24 hours past due date. Late programs and reports will not be accepted for the final project. The bonus credits may be accumulated up to a total of 50% toward program and final project credits. Programs are graded 80% for functionality and correctness and 20% for style, readability, documentation/writeup, and efficiency. Additional points may also be earned for extra features.

Submission:

Create and submit a subdirectory called prog1. It should contain the executable and all the files you have to make your program compile/run. Include the other items to be submitted in this directory as well. Submission must be done using the submit utility from CATS (e.g. unix.ic.ucsc.edu).

submit cmps161-ap.w10 prog1 prog1.tar, or
submit cmps161-ap.w10 prog1 prog1.zip,