Look over ImageBlur.java and ImageRotate.java. See how they work. You can try on

sample photos posted or any png image you want.

$3.$ Now Try to multithread these two programs. Hint: Think about dividing up the image

to be processed by separate threads.

$4.$ Compare the runtime of the algorithms on the images for the parallel and regular

versions

"ImageBlur.java"

import javax.imageio.ImageIO;

import java.awt.$*$;

import java.awt.image.BufferedImage;

import java.io$.$File;

import java.io$.$IOException;

public class ImageBlur

$\{$

public static BufferedImage gaussianBlur$($BufferedImage src$)$

$\{$

int radius $=5$; $//$ Blur radius

int size $=$ radius $*2+1$;

$//$ Create a Gaussian kernel

double$[][]$ kernel $=$ new double$[$size$][$size$]$;

double sigma $=$ radius $/3\mathrm{.}0$;

double sum $=0\mathrm{.}0$;

for $($int x $=-$radius; x $<=$ radius; x$++)$

$\{$

for $($int y $=-$radius; y $<=$ radius; y$++)$

$\{$

double value $=($double$)$ Math.exp$(-($x $*$ x $+$ y $*$ y$)/(2*$ sigma $*$ sigma$))$;

kernel$[$x $+$ radius$][$y $+$ radius$]=$ value;

sum $+=$ value;

$\}$

$\}$

$//$ Normalize the kernel

for $($int x $=0$; x $<$ size; x$++)$

$\{$

for $($int y $=0$; y $<$ size; y$++)$

$\{$

kernel$[$x$][$y$]/=$ sum;

$\}$

$\}$

$//$ Create a new image to store the blurred result

BufferedImage blurred $=$ new BufferedImage$($src$.$getWidth$(),$ src$.$getHeight$(),$ src$.$getType$())$;

$//$ Apply the kernel to each pixel

for $($int x $=0$; x $<$ src$.$getWidth$()$; x$++)$

$\{$

for $($int y $=0$; y $<$ src$.$getHeight$()$; y$++)$

$\{$

double r $=0,$ g $=0,$ b $=0$;

$//$ Apply the kernel

for $($int kernelX $=-$radius; kernelX $<=$ radius; kernelX$++)$

$\{$

for $($int kernelY $=-$radius; kernelY $<=$ radius; kernelY$++)$

$\{$

int imageX $=$ Math.min$($Math$.$max$($x $+$ kernelX, $0),$ src$.$getWidth$()-1)$;

int imageY $=$ Math.min$($Math$.$max$($y $+$ kernelY, $0),$ src$.$getHeight$()-1)$;

Color color $=$ new Color$($src$.$getRGB$($imageX$,$ imageY$))$;

double kernelValue $=$ kernel$[$kernelX $+$ radius$][$kernelY $+$ radius$]$;

r $+=$ color.getRed$()*$ kernelValue;

g $+=$ color.getGreen$()*$ kernelValue;

b $+=$ color.getBlue$()*$ kernelValue;

$\}$

$\}$

$//$ Set the new pixel color

blurred.setRGB$($x$,$ y$,$ new Color$(($int$)$ r$,($int$)$ g$,($int$)$ b$).$getRGB$())$;

$\}$

$\}$

return blurred;

$\}$

public static void main$($String$[]$ args$)\{$

try $\{$

$//$ Load the image

BufferedImage image $=$ ImageIO.read$($new File$($args$[0]))$;

System.out.println$($image$)$;

$//$ Apply Gaussian blur

BufferedImage blurredImage $=$ gaussianBlur$($image$)$;

$//$ Save the blurred image

ImageIO.write$($blurredImage$,"$png$",$ new File$("$blurred$\_"+$args$[0].$split$("\backslash \backslash .")[0]+".$png$"))$;

$\}$ catch $($IOException e$)\{$

e$.$printStackTrace$()$;

$\}$

$\}$

$\}$

"ImageRotate.java"

import javax.imageio.ImageIO;

import java.awt.$*$;

import java.awt.image.BufferedImage;

import java.io$.$File;

import java.io$.$IOException;

public class ImageRotate

$\{$

public static BufferedImage rotateImage$($BufferedImage src$,$ double angle$)$

$\{$

$//$ Calculate the new dimensions of the rotated image

double radians $=$ Math.toRadians$($angle$)$;

int width $=$ src$.$getWidth$()$;

int height $=$ src$.$getHeight$()$;

$//$ Calculate the size of the new image

int newWidth $=($int$)$ Math.abs$($width $*$ Math.cos$($radians$))+($int$)$ Math.abs$($height $*$ Math.sin$($radians$))$;

int newHeight $=($int$)$ Math.abs$($height $*$ Math.cos$($radians$))+($int$)$ Math.abs$($width $*$ Math.sin$($radians$))$;

$//$ Create a new image with the calculated dimensions

BufferedImage rotatedImage $=$ new BufferedImage$($newWidth$,$ newHeight, src$.$getType$())$;

Graphics$2$D g$2$d $=$ rotatedImage.createGraphics$()$;

$//$ Set the rotation point to the center of the new image

g$2$d$.$translate$($newWidth $/2,$ newHeight $/2)$;

g$2$d$.$rotate$($radians$)$;

g$2$d$.$translate$(-$width $/2,-$height $/2)$;

$//$ Draw the original image onto the rotated image

g$2$d$.$drawImage$($src$,0,0,$ null$)$;

g$2$d$.$dispose$()$;

return rotatedImage;

$\}$

public static void main$($String$[]$ args$)$

$\{$

try

$\{$

$//$ Load the image

BufferedImage image $=$ ImageIO.read$($new File$($args$[0]))$;

$//$ Rotate the image by $90$ degrees

BufferedImage rotatedImage $=$ rotateImage$($image$,90)$;

$//$ Save the rotated image

ImageIO.write$($rotatedImage$,"$png$",$ new File$("$rotated$\_"+$args$[0].$split$("\backslash \backslash .")[0]+".$png$"))$;

$\}$ catch $($IOException e$)$

$\{$

e$.$printStackTrace$()$;

$\}$

$\}$

$\}$