HW 8 (Images Part 2)

As in the Image Lab in class and in HW7, you'll practice image modification.

Mount the COURSES drive and create a folder called hw8 in your STUWORK folder. Open the new folder in VSCode. If you need a refresher on how to complete these steps, refer back to the in-class lab from the first day of class.

Download the starter code and move the files (images2.py, cImage.py, and the test images) into your hw8 folder.

If you are working on your own computer, you may need to install the Python package pillow. To do so, run the following command from the terminal:

pip3 install pillow

If that doesn't work, you can try pip install pillow instead. If that still doesn't work, reach out for help, and in the meantime, work on the lab computers.

For this part, you'll write a filter that blurs an image, as illustated by the following image:

You'll complete the function blur that takes in one parameter, an Image object. blur should return a new Image object whose pixels have been modified from the original to appear blurred. This might seem like a silly function to create, but blurring is an important part of many algorithms that try to extract information from images because it removes noise.

To create a blurred pixel, you should set its RGB values equal to the average color value of each of its 8 neighbors plus itself. That is, if a pixel is at coordinates (x,y), you should set the new pixel to the average of pixels (x-1, y-1), (x-1, y), (x-1, y+1), …, (x, y), …, (x+1, y+1). You'll need to make sure that the pixels on the edges of the image are handled correctly (i.e., only take the average color value of pixels that exist).

Make sure that you are always accessing the pixel values from the original image, not the partially blurred new image. (Otherwise, your image will get progressively more blurred as you iterate through the rows and columns of pixels.)

For this part, you'll complete the function mirror that mirrors an image across a vertical axis. For instance, the pixel that is originally at coordinate (0, 0) will end up at coordinate (0, imageWidth-1). The final result will be something like this:

The function mirror will take one parameter, an Image object, and will return a new Image object where the pixels have been rearranged to be a mirrored copy of the original.

When you're finished, make sure to complete the usual documentation steps. This includes adding comments, writing function docstrings, and adding a top-level comment, acknowledgements, and a reflection to the header.

You should also think about coding style. Have you written everything in a consistent way that is easy to read? Does your code have any unnecessary print statements? (Remove them.) Is there any repetitive code that could be rewritten to use loops or helper functions? Review the style document on Moodle for the expectations for this assignment.

You can test both functions by calling testFilter as we did in the lab and in HW7. For example, testFilter("cat.png", blur) or testFilter("cat.png", mirror).

This assignment was adapted from Layla Oesper's teaching materials. Thanks for sharing!