use URL of file path to convert image to gray scale
edit process.java --> line 27 for output file location
javac *.java
java process int p = img.getRGB(x,y);
int a = (p>>24)&0xff;
int r = (p>>16)&0xff;
int g = (p>>8)&0xff;
int b = p&0xff;
//calculate average
int avg = (r+g+b)/3;
//replace RGB value with avg
p = (a<<24) | (avg<<16) | (avg<<8) | avg;
img.setRGB(x, y, p);EDGE --> set of points where discontinuities in brigthness occur
by using derivative (by filters) calculate the points of discontinuities
1st derivative 2nd derivative
convoultion
test
https://medium.com/javarevisited/building-a-java-edge-detection-application-6147b68e5d79