CS-171

CS-171

Program 4: A Picture Collage

Objective

The objectives of this assignment include the following:

Understanding the multiple coordinate systems involved in picture to picture translations
Effectively using nested loops to control transformations in limited pixel ranges
To both understand and to translate into Java programming code many common transformations performed on two dimensional images
To use all of the above to create an interesting picture.

Assignment

For this assignment you will be creating a collage of images. You should choose your images and composition to reflect the interest that you have so that your collage tells us something about who you are. You will be creating a variety of image manipulation routines that will be needed to create your collage. Below is an example collage that was created by Dr. Kretchmar from the CS department. His particular interests include running marathons and cycling.

Requirements

The requirements for this assignment can be partitioned broadly into (i) the base requirements (including following the instructions faithfully), (ii) a few required transformations, and (iii) a set of optional transformations. Points are awarded in each category.

Base Requirements

(15pts) Make the following additions/changes to your Picture.java file. Submit this file in a folder named prog4 that you create in your Assignment Inbox. You will also need to create an application class with a main method that is responsible for retrieving the input pictures from disk, creating Picture objects, invoking transformations on those objects, and finally writing out the resultant picture to the disk as a jpeg file. Also submit copies of your original images (described below) and your final collage project in a file named collage.jpg. Please be sure to use all these filenames exactly as they are spelled here.
(10pts) Your collage must have at least four images including one for the background if you wish to create your collage in this way (note that the example above only has three images). You are welcome to include more pictures as your design dictates. Search for images that reflect what you do and who you are (they will all have to be jpg files). Compose your images artistically.

Core Transformations

(15pts) You must use a scaling routine at least once.
(15pts) You must use a cropping routine at least once.
(15pts) You obviously must use an overlay routine to place the images on the collage.
For all of your image manipulation routines, the method should create and ultimately return a new Picture instance that contains the specified changes so that the original image is left unchanged. (This is the design choice we have been making consistently in class.).

Note that the above requirements will earn 70 points on this assignment. You have ample opportunity to earn additional points as described below:

Elective Transformations

(5 pts) Convert your posterize and rotate colors applications into corresponding posterize() and rotateColors() methods in the Picture class. Think about useful parameters for these methods that may make them more general (hint: if you created multiple versions of the Posterize and RotateColors applications, ask yourself if the use of parameters could unify the differences into single method).
(10 pts) Write a cropping routine that extracts a circle instead of a rectangle.
(10 pts for the set of all three) Write routines to rotate the image by 90, 180, and 270 degrees.
(5 pts) Generalize your circle cropping routine to extract an ellipse (oval). Note: These are five additional points plus you must also do the circle routine.
(5 pts) Write a second overlay routine that considers ”pure black” as transparent.
(10 pts) Write a routine to rotate an image through an arbitrary angle between 0 and 360 degrees.
(10 pts) Do you remember what you look like in those ”fun house” carnival mirrors that distort your image? Write a routine to perform these fun house mirror distortions.
(? pts) Do you have other creative ideas? Ask the instructor and receive additional bonus points for some other image manipulation routine.

Details:

Scale: Provide a scaling factor as a double. Multiply the dimensions by this factor to increase/decrease the height and width of the object. Expand or contract the pixels to create a new copy of the original image. Name your method scale.
Crop: Cropping is the act of removing a portion of an image. You need to specify the upper/left coordinates of the rectangular region to extract along with the width and height of the rectangular region to extract. Return a new image of the appropriate dimensions that contains only the cropped region. Name your routine crop. Gracefully handle the case where the cropped region extends beyond the borders of the original image.

Overlay: Place one image overtop of another. You should provide the (x,y) coordinates to specify the upper/left corner of the overlay position. If the overlain image extends beyond the boundaries of the underlying image, then ignore that portion of the overlain image and copy as much as is possible. Name your method overlay.

Circle Crop: Obviously you must create a rectangualr (square) image, but extract only a circular portion of the original image and make the outer boundaries of the square pure black (so it works especially well with a transparent overlay described below). Specify the center (x,y) and radius of the cropping. Name your method cropCircle. Handle the case where the circle extends the boundaries of the original image.
Transparent Overlay: Same as an overlay except that any pure black areas in the overlaying image ”bleed through” and pick up the underlying image below. Name your method transparentOverlay.
Ellipse Crop: Remember an ellipse? Two centers and a constant sum of distances? This allows you to do oval croppings. Name your method cropEllipse.

Rotation1: Rotate an image 90, 180, and 270 degrees clockwise. Name your methods rotate90, rotate180, and rotate270.

Rotation2: Specify the angle of rotation (in degrees) between 0 and 360 (actually allow any arbitrary angle including negative angles). Rotate the image counter clockwise in this many degrees. Name your method rotate.

Carnival Mirror: Mirrors either distort horizontally or vertically but usually not both. So you can choose one or implement both. Consider the horizontal distortion: the vertical distances are all left unchanged. But the horizontal features are either expanded or compressed from the mid axis running vertically through the image. You can use a sine function to nicely imitate this gradual compression/expansion. Name your method carnivalMirror.

Out of bounds?: Many of these routines will create images that exceed the dimensions of the source image. If you need to put a pixel out of bounds, then obviously just ignore it (this part of the image will be omitted).

Others: If you create your own image manipulation routines, then be sure to comment them extensively so that we know how to use them and what they are supposed to do.