Class Pict

  • public class Pict
extends java.lang.Object
    This utility class contains static methods to translate between images and 2-D arrays.

    To convert a image's filename or URL to an array of int:

         int[][] myPixels;
     myPixels =  Pict.fileToPixelsBW( "https://www.radford.edu/~itec120/2012fall-ibarland/Lectures/lect01-ufo/muse.jpeg" );
     Pict.displayPixels( myPixels );   // Bring up a window with the image.
     myPixels[13][23] = 255;           // Set location (13,23) to white.
     myPixels[14][23] =   0;           // Set location (14,23) to black.
     Pict.displayPixels( myPixels );   // Look for the modified pixel.

    Note that once you have displayed an image, modifying the array won't retroactively change that image; you'll have to call displayPixels again after making any modifications to see a new image.

    Optional/Challenge:

    If you want to deal with color images, you can use imageToPixelsColor, which will return an array of java.awt.Color objects. See the Java API for details, but the most useful color methods are getRed(), setRed(int), and similarly for green and blue. To display a color image (if you have a 2-D array of Colors), call displayPixels( Color[][] ).

    • Constructor Summary

      Constructors 
      Constructor Description
      Pict()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static void displayPixels​(int[][] pixels)
      Given an array of grayscale values in [0,256), draw it as a black-and-white image.
      static void displayPixels​(java.awt.Color[][] pixels)
      Given an array of Colors, draw it as a Color image.
      static int[][] fileToPixelsBW​(java.lang.String filenameOrURL)
      Given a filename or URL, return a 2-D array of grayscale values in [0,256).
      static java.awt.Color[][] fileToPixelsColor​(java.lang.String filenameOrURL)
      Given a filename or URL, return a 2-D array of java.awt.Colors.
      static void main​(java.lang.String[] args)
      A test method, which just displays three images: A color version, a black-and-white version, and a tiny 4x3 image.

      • Methods inherited from class java.lang.Object

        clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • Pict

        public Pict()

    • Method Detail

      • displayPixels

        public static void displayPixels​(int[][] pixels)
        Given an array of grayscale values in [0,256), draw it as a black-and-white image. (Of course, subsequent changes to the array won't retroactively change this image.)
        Parameters:
        pixels - A 2-D array of grayscale values in [0,256).

      • displayPixels

        public static void displayPixels​(java.awt.Color[][] pixels)
        Given an array of Colors, draw it as a Color image. (Of course, subsequent changes to the array won't retroactively change this image.)
        Parameters:
        pixels - A 2-D array of java.awt.Colors.

      • fileToPixelsBW

        public static int[][] fileToPixelsBW​(java.lang.String filenameOrURL)
        Given a filename or URL, return a 2-D array of grayscale values in [0,256).
        Parameters:
        filenameOrURL - A string like "H:\MyFile.jpeg" or "https://www.radford.edu/someUser/somePict.jpg"
        Returns:
        The 2-D array of grayscale values representing the indicated picture. Will cause a run-time exception if the file/URL can't be opened.

      • fileToPixelsColor

        public static java.awt.Color[][] fileToPixelsColor​(java.lang.String filenameOrURL)
        Given a filename or URL, return a 2-D array of java.awt.Colors.
        Parameters:
        filenameOrURL - A string like "H:\MyFile.jpeg" or "https://www.radford.edu/someUser/somePict.jpg"
        Returns:
        The 2-D array of grayscale values representing the indicated picture. Will cause a run-time exception if the file/URL can't be opened.

      • main

        public static void main​(java.lang.String[] args)
        A test method, which just displays three images: A color version, a black-and-white version, and a tiny 4x3 image.