Cropping an image succintly

Question

I am constantly frustrated by how complicated it is to write graphical programs that would have been only a few lines of code 20+ years ago. Since the invention of the mouse this has become even worse it seems. I was hoping someone could put me out of my misery and show the shortest code to do the following really basic "modern" operations.

The code will read in an image in any sensible format of your choosing (png, jpg, etc.), display it on the screen, allow you to choose a rectangular region with your mouse and then just save the selected region as an image file.

You are free to use any programming language and any library which hasn't been written especially for this competition. Both should be freely (in both senses) online. The code should be runnable in linux.

To start things off.... here is a very lightly golfed solution in python modified from code to Andrew Cox from https://stackoverflow.com/questions/601874/digital-image-cropping-in-python which takes 1294 1101 characters.

import pygame, sys
from PIL import Image
pygame.init()

def displayImage( s, px, t):
    s.blit(px, px.get_rect())
    if t:
        pygame.draw.rect( s, (128,128,128), pygame.Rect(t[0], t[1], pygame.mouse.get_pos()[0] - t[0], pygame.mouse.get_pos()[1] - t[1]))
    pygame.display.flip()

def setup(path):
    px = pygame.image.load(path)
    s = pygame.display.set_mode( px.get_rect()[2:] )
    s.blit(px, px.get_rect())
    pygame.display.flip()
    return s, px

def mainLoop(s, px):
    t = None
    b = None
    runProgram = True
    while runProgram:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                runProgram = False
            elif event.type == pygame.MOUSEBUTTONUP:
                if not t:
                    t = event.pos
                else:
                    b = event.pos
                    runProgram = False
        displayImage(s, px, t)
    return ( t + b )


s, px = setup(sys.argv[1])
left, upper, right, lower = mainLoop(s, px)
im = Image.open(sys.argv[1])
im = im.crop(( left, upper, right, lower))
im.save(sys.argv[2])

I believe it is traditional to give a time limit, so I will accept the best answer in exactly one week's time.

Current count

• Octave - 44 + 15 = 59 characters
• R - 305 characters
• Python - 343 characters
• Java - 560 characters

Answer 1

Octave - 59 chars

pkg load image;imwrite(imcrop(imread(input(''))),input(''))

MATLAB - 44 chars (not free, out of the contest)

imwrite(imcrop(imread(input(''))),input(''))

MATLAB seemed spot-on for this. Requires the Image Processing Toolbox (or package image 2.0.0 from Octave Forge). Usage:

1. Write at prompt 'input-filename' (single quotes included)
2. MATLAB: Drag from top-left to bottom-right corner and double click the rectangle. Octave: Click top-left and bottom-right corner
3. Write 'output-filename' (between single quotes too)

Answer 2

Java (580 560 559)

import java.awt.*;import javax.imageio.*;public class R extends
Frame{static java.awt.image.BufferedImage i;int
x,y,w,h;{setSize(i.getWidth(),i.getHeight());setUndecorated(0<1);show();}public static void
main(String[]a)throws Exception{i=ImageIO.read(System.in);new R();}public boolean handleEvent(Event
e){if(e.id==501){x=e.x;y=e.y;}if(e.id==502){w=e.x-x;if(w<0)x-=w=-w;h=e.y-y;if(h<0)y-=h=-h;try{ImageIO.write(i.getSubimage(x,y,w,h),"png",System.out);System.exit(0);}catch(Exception
E){}}return 0<1;}
public void paint(Graphics g){g.drawImage(i,0,0,this);}}

Takes input image from stdin and writes cropped image to stdout. You can drag in whichever direction you choose and it will automatically flip the coordinates as required. Input in GIF, PNG, JPEG, TIFF, probably one or two others; output in PNG.

With whitespace and a couple of comments:

import java.awt.*;
import javax.imageio.*;

// Extending Frame is the simplest and ugliest way of showing a GUI.
public class R extends Frame {

    // static so that we can read it in main() and save a try/catch block
    static java.awt.image.BufferedImage i;
    int x,y,w,h;

    // Instance initialiser ~= constructor without the signature
    {
        setSize(i.getWidth(),i.getHeight());
        // Don't show frames. This saves handling inset dimensions everywhere
        setUndecorated(0<1);
        show();
    }

    public static void main(String[]a) throws Exception
    {
        i=ImageIO.read(System.in);
        new R();
    }

    // This is deprecated, but it's the shortest way of handling events.
    // I learnt this trick from the Java4k Game Competition
    public boolean handleEvent(Event e) {
        if (e.id == 501) { // MOUSE_DOWN
            x=e.x;
            y=e.y;
        }
        if (e.id == 502) { // MOUSE_UP
            w = e.x - x;
            // If the second click was to the left of the first one, flip them.
            if (w < 0) x -= w = -w;
            h = e.y - y;
            // Similarly.
            if (h < 0) y -= h = -h;

            try {
                ImageIO.write(i.getSubimage(x,y,w,h), "png", System.out);
                System.exit(0);
            } catch(Exception E){
            }
        }
        return 0<1;
    }

    public void paint(Graphics g) {
        g.drawImage(i,0,0,this);
    }
}

Answer 3

R - 325 305 characters

f=scan(,"");l=locator;r=round;i=as.raster(png::readPNG(f));n=nrow(i);m=ncol(i);x11(h=7,w=7*m/n);p=function(X){par(mar=rep(0,4));m=ncol(X);n=nrow(X);plot(c(1,m),c(1,n),xaxs="i",yaxs="i");rasterImage(X,1,1,m,n)};p(i);a=l(1);b=l(1);j=i[r(n-a$y):r(n-b$y),r(a$x):r(b$x)];png(w=ncol(j),h=nrow(j));p(j);dev.off()

Or fully developed:

f=scan(,"")
l=locator
r=round
i=as.raster(png::readPNG(f))
n=nrow(i)
m=ncol(i)
x11(h=7,w=7*m/n)
p=function(X){
par(mar=rep(0,4))
m=ncol(X)
n=nrow(X)
plot(c(1,m),c(1,n),xaxs="i",yaxs="i")
rasterImage(X,1,1,m,n)
}
p(i)
a=l(1)
b=l(1)
j=i[r(n-a$y):r(n-b$y),r(a$x):r(b$x)]
png(w=ncol(j),h=nrow(j))
p(j)
dev.off()

Tested on a Mac, untested on Linux but should work.
Package png needs to be installed.
At prompt, should be provided with path to png file to crop. Then when the picture appears, click twice: once for the left upper corner of selection rectangle and a second time for the right lower corner.
Create a cropped png file in working directory with default name ("Rplot001.png").

Answer 4

Java (Applet), 706 698 590

By no means is Java ever considered terse, and it certainly doesn't have the most elegant handling of image display or mouse interaction, but this really isn't that bad. I'm wondering if a solution using Swing or some other library might be shorter.

import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.imageio.*;


public class R extends java.applet.Applet{
    Scanner s=new java.util.Scanner(System.in);
    java.awt.image.BufferedImage i;
    int x,y;
    {
        try{
            i=ImageIO.read(new File(s.nextLine()));
        }catch(Exception e){}
        addMouseListener(new MouseAdapter(){
            public void mousePressed(MouseEvent e){
                x=e.getX();y=e.getY();
            }
            public void mouseReleased(MouseEvent e){
                try{
                    ImageIO.write(i.getSubimage(x,y,e.getX()-x,e.getY()-y),"png",new File(s.nextLine()));
                }catch(Exception z){}
            }
        });
    }
    public void paint(java.awt.Graphics g){
        g.drawImage(i,0,0,this);
    }
}

Answer 5

Python/PyGame (343C)

Usage:

python this.py image.png result.png

which read from image.png and write to result.png.

import pygame as P
import sys
D=P.display
I=P.image
D.init()
f,g=sys.argv[1:3]
m=I.load(f)
s=D.set_mode(m.get_size())
r=k=0
c=1
while c:
 for e in P.event.get():
  t=e.type
  if t==5:x,y=e.pos;k=1
  if t==4 and k:i,j=e.pos;r=(x,y,i-x,j-y)
  if t==6:c=0
 s.blit(m,(0,0))
 if r and c:P.draw.rect(s,0,r,1)
 D.flip()
q=s.subsurface(r)
I.save(q,g)

Answer 6

I know the time limit is up, but here's how to do it in 34 characters using Bash:

display $1&K=$!;import $2;kill $K

Call it like this: 'script.sh input.png output.png'.

This uses the ImageMagick tools/library to first display the image. Then it lets you select an area to take a screenshot of using the mouse. This screenshot is effectively a crop of the image. Finally, the display is closed.