A1: Introduction to digital pictures and color Questions: 1. How many bits does it take to represent the values from 0 to 255?

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1 AP Computer Science Picture Lab Name: Michael Metz A1: Introduction to digital pictures and color Questions: 1. How many bits does it take to represent the values from 0 to 255? 8 bits 2.How many bytes does it take to represent a color in the RBG color model? 3 bytes 3.How many pixels are in a picture that is 640 pixels wide and 480 pixels high? 640 * 480 = pixels A2: Picking a color Questions: 1.How can you make pink? R: 255 G: 0 B: How can you make yellow? R: 255 G: 255 B: 0 3.How can you make purple? R: 115 G: 0 B: How can you make white? R: 255 G: 255 B: How can you make dark gray? R: 75 G: 75 B: 75

2 A3: Exploring a picture Questions: 1.What is the row index for the top left corner of the picture? 0 2.What is the column index for the top left corner of the picture? 0 3.The width of this picture is 640. What is the right most column index? The height of this picture is 480. What is the bottom most row index? Does the row index increase from left to right or top to bottom? top to bottom 6.Does the column index increase from left to right of top to bottom? left to right 7.Set the zoom to 500%. Can you see squares of color? This is called pixelation. Pixelation means displaying a picture so magnified that the individual pixels look like small squares. yes Exercises: 1. Copy the line(s) in the main() method that you changed and paste them here. Run the main method again, take a screen shot of your computer screen (press the [ctrl] and [Print Scrn] buttons at the same time) and paste the screen shot below your line(s) of code. public static void main( String args[]) { /*Picture pix = new Picture("beach.jpg"); pix.explore();*/ Picture pix = new Picture("wall.jpg"); pix.explore();

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4 A4: Two-dimensional arrays in Java Exercises: 1. Copy the lines of code from your getcount() method and paste them here. public int getcount(int a){ int num = a; int x = 0; for(int m = 0; m < matrix.length; m++) for(int n = 0; n < matrix[0].length; n++) if(num == matrix[m][n]) x++; return x; After uncommenting the testgetcount() method and the call to it in the main() method of IntArrayWorkerTest, what is printed? Copy and past the output shown in your terminal window here: Count should be 6 and count is 6 2.Copy the lines of code from your getlargest() method and paste them here. public int getlargest(){ int num = 0; for(int x = 0; x < matrix.length; x++) for(int z = 0; z < matrix[0].length; z++) if(num < matrix[x][z]) num = matrix[x][z]; return num; After uncommenting the testgetlargest() method and the call to it in the main() method of IntArrayWorkerTest, what is printed? Copy and past the output shown in your terminal window here: Largest should be 6 and is 6 Largest should be 6 and is 6 Largest should be 6 and is 6 Largest should be 6 and is 6 3.Copy the lines of code from your getcoltotal() method and paste them here.

5 public int getcoltotal(int r){ int num = 0; for(int x = 0; x < matrix.length; x++) num += matrix[x][r]; return num; After uncommenting the testgetcoltotal() method and the call to it in the main() method of IntArrayWorkerTest, what is printed? Copy and past the output shown in your terminal window here: Total for column 0 should be 5 and is 5 Total for column 1 should be 7 and is 7 Total for column 2 should be 9 and is 9

6 A5: Modifying a picture Questions: 1. Open Picture.java and look for the method getpixels2d. Is it there? No 2.Open SimplePicture.java and look for the method getpixels2d. Is it there? Yes 3.Does the following code compile? EXPLAIN. DigitalPicture p = new DigitalPicture(); NO, you cannot instantiate a object from a interface, A interface can be a pointer but you cannot instantiate it! 4.Assuming that a no-argument constructor exists for SimplePicture, would the following code compile? EXPLAIN. DigitalPicture p = new SimplePicture(); Yes, like I said in the above answer, A interface can be a pointer but you cannot instantiate it!. The interface DigitalPicture is pointing to a SimplePicture object, and SimplePicture implements the DigitalPicture interface. 5. Assuming that a no-argument constructor exists for Picture, does the following code compile? EXPLAIN. DigitalPicture p = new Picture(); Yes, like I said in the above answer, A interface can be a pointer but you cannot instantiate it!. The interface DigitalPicture is pointing to a Picture object, and Picture extends SimplePicture which implements the DigitalPicture interface. 6. Assuming that a no-argument constructor exists for Picture, does the following code compile? EXPLAIN. SimplePicture p = new Picture();

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9 5. Copy the lines of code from your grayscale() method and paste them here. public void grayscale(){ Pixel[][] pixels = this.getpixels2d(); for (Pixel[] rowarray : pixels) for (Pixel pixelobj : rowarray) { double average = ((pixelobj.getgreen()) + (pixelobj.getblue()) + (pixelobj.getred())) / 3.0; pixelobj.setred((int) average); pixelobj.setgreen((int) average); pixelobj.setblue((int) average); Copy the lines of code from your new static tester method in the PictureTester class and paste them here. public static void testgrayscale(){ Picture beach = new Picture("beach.jpg"); beach.explore(); beach.grayscale(); beach.explore(); After calling this tester method in the main() method of PictureTester, take a screen shot, and paste your image here:

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14 3. Copy the lines of code from your mirrorhorizontlbottotop() method and paste them here. public void mirrorhorizontalbottotop() { Pixel[][] pixels = this.getpixels2d(); Pixel toppixel = null; Pixel bottompixel = null; int height = pixels.length; for (int row = 0; row < height / 2; row++) for (int col = 0; col < pixels[0].length; col++){ toppixel = pixels[row][col]; bottompixel = pixels[height row][col]; toppixel.setcolor(bottompixel.getcolor()); Copy the lines of code from your new static tester method in the PictureTester class and paste them here. public static void testmirrorhorizontalbottotop() { Picture caterpillar = new Picture("caterpillar.jpg"); caterpillar.explore(); caterpillar.mirrorhorizontalbottotop(); caterpillar.explore(); After calling this tester method in the main() method of PictureTester, take a screen shot, and paste your image here:

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