Image Processing 1

This assignment is to be done with your teammate.

Overview

This is your chance to practice some basics of image processing. This is a warmup to the next assignment, where you'll do some "green screen"-like special effects.

Getting Started

Create a directory called image1 for this assignment. To facilitate reading in, storing, and manipulating image files in "standard" formats (like .jpg, .gif, and .png), we will use a module called images.py. Copy images.py into your directory from the above link or from the course website. The documentation for images.py can be found here.

If you're working on your own computer, you'll also need to install the Python Imaging Library (PIL), which images.py uses. Follow these instructions for installing PIL under Windows XP or Mac OS X. We already have PIL installed on the department Macs.

You'll also need some images to work with. Download dave.jpg, and amy.jpg into the same directory as images.py, or alternatively use your own image files.

Applying basic filters to an image

We'll start out with some basic image manipulations first. Your task is to write a Python module called photolab.py. It should contain the following functions:

• onlyRed(image)
  Creates and returns a new image containing only the red aspects of the original image. You can do this by setting all the green and blue values to 0.
• negate(image)
  Creates and returns a new image that is a conversion of the original image to "negative" form (like a photographic negative). Here, you don't necessarily have to duplicate precisely the same technical visual effects that a photonegative actually uses. But you should modify all colors in a way that turns black into white, white into black, dark colors into light, light into dark, etc.
• main()
  Write a main() function that tests the above functions by using an image file and making red and negative versions of it appear on the screen. When we test your code, we will remove your main() and add our own. If you have carefully followed the above specifications, it should work perfectly! As an example, we should be able to write code in our main() like:

  imageOriginal = FileImage('dave.jpg')
  redImage = onlyRed(imageOriginal)
  redImage.show('Only red',0,300)
  

Good luck, and have fun! Remember that lab assistants are available in the evenings in CMC 306 to help out if you need it.