Flashcards in Ch. 5 Test Deck (72)
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Objects give programmers...
Access to complex behavior
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Objects can manipulate...
Digitally encoded images and sounds
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Until 20 years ago, computers mostly...
Processed numbers and text
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Digital image processing includes:
-capturing images with scanners and cameras
-representation and storage of images in efficient file formats
-construction of algorithms used in image-manipulation programs (like photoshop)
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(The essential properties of images) When an image is loaded in a program...
The bits map into a rectangle of colored dots (pixels)
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(The essential properties of images)
The coordinates of the grid range from:
-(0,0) at the upper right corner to (width-1, height-1) at the lower right corner
-width and height are the dimensions in pixels
-x-coordinates increase positively to the right, y-coordinates increase positively to the bottom.
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An image consists of...
A width, height, and a set of pixels
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Each pixel is accessible by...
It's (x,y) coordinates
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A pixel contains...
Integer values that represent color in terms of RGB
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The pixel at the upper left corner is at...
(0,0)
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Image manipulation operations:
Transfer images to and from files and storage in RAM
After loading into RAM, can retrieve or modify a pixel at any grid position
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Image manipulation operators allow the program to
Rotate an image
Convert color to gray scale or add filters
Highlight blur or sharpen all or part of an image
Control brightness and perform edge detection
Enlarge or reduce size and apply color inversion
Morph an image into another image
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The images package defines classes that allow the programmer to
-load an image from a file
-view the image in a window
-examine and manipulate an image's pixels
-update the window with changes
-save the image back to a file
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APImage and Pixel classes:
The two most important classes in the images package
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APImage method includes
Creating an image from a file or a blank image
Returning images height and width
Saving the image
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The pixel class...
Represents a pixel
-an object of this class contains three integer values to represent the pixels RGB components
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Simple image processing program
A program that loads an image from its file and draws it in a window
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The first statement of a simple image processing program
Imports the relevant class, APImage, from the images package
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The second statement of a simple image processing program
Uses object instantiation to make a new object available to the program and instantiates the class
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The third statement of a simple image processing program
Runs the draw method on the object to display it in a window
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Java might raise an error if...
There is not enough ram to hold an image
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Heap space
The area of ram reserved for Java objects
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To prevent a crash...
Adjust the heap space for data memory using the Xmx command-line option
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Object based programming uses..
Existing classes objects and methods to solve problems
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To use an object the programmer must know...
It's interface (the set of methods it recognizes)
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An interface contains:
The headers of methods and supporting comments about their use (including methods' names, types of parameters they expect, and types of values they return, if any)
No info about how methods work is provided
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Application programming interface
The set of interfaces in a package or language
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Mutators
Methods that do not return a value
-used to modify the internal contents of an object
-setPixel and setRed
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Accessors
Methods that return values
-allows users to examine part of an objects contents
-toString() returns a strong representation of the data combined in an object
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