CS 2010 Homework 2 FAQ

What exactly are we supposed to do for problem 2.2 (HtDP 5.1.2)?

Just write guess-target, which has the contractnum num -> sym

The image-includes? and find-image functions don't work right with my images.

Be sure not so save sub-pictures in JPEG format. When you re-open the JPEG file, the pixels will not be exactly the same as before.

Also, converting an image to GIF can have unexpected effects. For example, the following sequence does not work:

• Open a JPG
• Copy a part
• Save the part as a GIF
• Save the orignal as a GIF

The problem is that converting a JPG to GIF tends to change the colors in the image slightly, and the colors might change differently for the smaller image than in the original image.

The following normally works:

• Open a JPG
• Save the orignal as a GIF
• Close the JPG, open the GIF
• Copy a part
• Save the part as a GIF

I don't care to make images myself. Are some available?