Picture processing, Part 2

This homework will give you more experience working with pictures, writing more expressions and statements. As with previous homeworks, you must also submit a time log.  This homework is to be done alone. It will be graded as follows:

• 15% - Posterize
• 10% - Inverse
• 15% - Offset
• 15% - Blend
• 15% - PictureSolutionHW4
• 20% - Code style
• 10% - Time log

Your Assignment

For this homework, you must write some more picture classes (i.e., programs).  Each will create a picture by implementing the Picture interface.  You must name your picture classes as follows:

• Posterize: Create a picture that "posterizes" an input picture.  Posterized pictures are limited to just a few values for each color.  For example, here is an input picture and the posterized version of it:

Now, how would you posterize a picture? For starters, you posterize a picture by posterizing each pixel.  And you can posterize a pixel by posterizing the red, green and blue components of each color. But, how do you do that? Well, each color component has a value between 0.0 and 1.0. To posterize it, you need to restrict components with values <= 0.5 to 0.0 and with values > 0.5 to 1.0. Think how you might use an "if" statement to transform a color component from the range 0.0 - 1.0 to having the discrete values of either 0.0 or 1.0.

To manipulate colors, you can use the PictureColor.getRed(), getGreen(), and getBlue() methods to get each color component.  Then, after you have computed all three new color components, you can construct a new color with those values and return that.  Documentation for these and all methods provided for this homework is available online.

Your constructor must have the signature:

    public Posterize(Picture basePicture);
 

• Inverse: Create a picture that inverts the value of each color component of each pixel.  That is, replace the red color component with 1.0 - the red component.  (i.e.: red = 1.0 - color.getRed()).  Here is an input picture and the posterized version of it:

Your constructor must have the signature:

    public Inverse(Picture basePicture);

 

• Offset: Create a picture that offsets an existing picture by a specified number of pixels in x and y. Note that the resulting picture will be larger than the input picture in any dimension that the offset is positive, and smaller than the input picture in any dimension that the offset is negative.  Here is an input picture and the result of offsetting it by (50, 50) followed by the result of offsetting it by (-50, -50).  Note that for negative offset values, the picture should be cropped from the top or left. [This paragraph updated to reflect an error in the description of how negative offsets should be handled, Feb 21, 6pm].

You can assume that the base picture's getColor() methods will always return valid PictureColors, even if the x and y values are outside the bounds of the pictures. For (x,y) values outside the dimensions of the base picture, you should return whatever color is returned by getColor() of the base picture. [This paragraph updated to reflect a copy & paste error, Feb 21, 6pm].

Your constructor must have the signature:

    public Offset(Picture basePicture, int newXOffset, int newYOffset);

 

• Blend: Create a picture that combines two input pictures. The resulting picture will have the largest dimension of each input picture.  You can find the maximum of two numbers by using an if statement.  Each pixel of the blended picture must evenly combine (i.e., average) the two pixels of the input pictures at that point. The red, green and blue components of each color must be averaged separately.  Here is a result of blending the above kitten picture with the Stripes from homework #3.

You can assume that the base pictures' getColor() methods will always return valid PictureColors, even if the x and y values are outside the bounds of the pictures. For each (x,y), you must blend whatever colors are returned by getColor() for the two base pictures, even if that (x,y) is outside the range of one or both of these base pictures.

Your constructor must have the signature:

    public Blend(Picture basePicture1, Picture basePicture2);

 

• PictureSolutionHW4: Finally, create a program that shows the result of running the picture classes you wrote. This time, you must combine them in the following specified ways.  As before, your demo program must show all these results.
  1. Original image - The version of PictureSolutionHW4 that is supplied with this assignment includes the creation of a single image and displays it.  Feel free to change the URL to point to any image on the web you like (that is not offensive).
  2. Posterize - Posterize the image from step 1 and display it.
  3. Inverse - Inverse the image from step 1 and display it.
  4. Offset - Offset the inverted image from step 3 by (50, 50) and display it.
  5. Blend the original image from step 1 and the same image that has been flipped left to right.  You should use FlipLeftRight which is supplied with this assignment to flip the image.
  6. Seeing Double - Blend the original image from step 1 and the same image that has been offset by (35, 0)).
  7. Emboss - Blend the original image from step 1 with an inverted version of that same image that has been offset by (1, 1)).

Since this is a private project, you can submit your time log as part of the project.  Just edit the timelog_hw4.txt file that is distributed with the hw4 project.

Submit your program by right-clicking on your project and select "Submit Project". Note that this option will only appear if you have successfully installed AutoCVS as described previously.  If you decide that you would like to make a change after you have submitted your project, you can resubmit as many times as you like before the extended deadline.  We will grade the last project submitted.