Description
1 The Pixel Class
A pixel is the the smallest unit of a picture that can be controlled. The color of a pixel can be represented
using the three component intensities red, green, and blue, which is referred to as the RGB model. For this
lab assignment, you will design and implement a class named Pixel that stores three unsigned char values
for the component colors red, green, and blue. Therefore a value for each component color is between 0 and
255. The class must have the following constructors, member functions, and overloads.
• Constructor that will accept three integer values for the component colors red, green, and blue. Use
default values of 255 for each color. Error checking is necessary since component color values must
be within the range of 0 to 255. If a value passed to the constructor is less than 0 then assign the
color component 0. Similarly, if a value is greater than 255 then assign the color component 255. The
process of limiting a value once it exceeds a threshold is often called clipping.
• Accessor functions red(), green(), and blue() that return the corresponding component color value.
• Functions setRed(int color), setGreen(int color), and setBlue(int color) set the corresponding component color. You may need to clip the values as described earlier. The functions should return
true if the value was in range, false if clipping was required.
Pixel pixel(207, 181, 59); // old-gold color, not the cigarette…
cout << pixel.red() << ’\n’; // prints the red component, which is 207
pixel.setGreen(270); // value too large, assign green the value 255
• grayscale() returns the grayscale value of the Pixel. The Pixel class stores the color using the RGB
model. The grayscale version of the color is a single unsigned char representing different shades of
gray, ranging from white to black. Given a RGB model, the conversion equation is
grayscale = 0.2989 × red + 0.5870 × green + 0.1140 × blue
• operator== return true if the corresponding component colors of the Pixel object are equivalent.
• operator!= return true if the corresponding component colors are not equivalent.
• operator+ return a Pixel object representing the sum of two Pixel objects. This overload will add
the corresponding color values of the two Pixel objects. Clipping? Yesssssssss….
• operator<< stream insertion operator neatly outputs in color using the format [1.0, 2.0, 3.0]
2 How Do I Test?
Testing will be done using a tester program which exercises functionality of the class. The example tester
program driver.cpp is available at the course web-site, however you will write your own in the future.
3 Programming Points
You must adhere to all of the following points to receive credit for this program.
• Turn-in (print-outs and electronically) the files for this program.
• The program must be broken into the following 3 files
1. pixel.h contains the class declaration
2. pixel.cpp contains the member function definitions
3. makefile is the makefile for the Pixel class and driver program, must be commented and have
make clean option.
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