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From: Knute Johnson <nospam@knutejohnson.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: Image Thinning using JAVA
Date: Tue, 26 Jun 2012 14:26:45 -0700
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On 6/26/2012 9:50 AM, sumera wrote:
> Hi!
> I have written some code in java to convert a colored image into black and white image and then tried to perform thinning on that gray-scale image. Black and white conversion is done successfully, but image thinning is still not giving correct output. Kindly help me in fixing my problem. My code is as follows:
>
> //colored image to black and white conversion; black and white image to thinned image.
>
> public static void main(String[] args)
> {
>      try
>      {
>          //colored image path
>          BufferedImage colored_image = ImageIO.read(new File("D:\\logo.jpg"));
>          //getting width and height of image
>          double image_width = colored_image.getWidth();
>          double image_height = colored_image.getHeight();
>          BufferedImage img = colored_image;
>
>          //drawing a new image
>          BufferedImage bimg = new BufferedImage((int)image_width, (int)image_height, BufferedImage.TYPE_BYTE_GRAY);
>          Graphics2D gg = bimg.createGraphics();
>          gg.drawImage(img, 0, 0, img.getWidth(null), img.getHeight(null), null);
>
>          //saving black and white image onto drive
>          String temp = "logo in blackAndwhite.jpeg";
>          File fi = new File("D:\\" + temp);
>          ImageIO.write(bimg, "jpg", fi);
>
>          //thinning by resizing gray scale image to desired eight and width
>          BufferedImage bimg2 = new BufferedImage((int)image_width, (int)image_height, BufferedImage.TYPE_INT_ARGB);
>          Graphics2D g2 = bimg2.createGraphics();
>
>          // Perform your drawing here
>          g2.setColor(Color.BLACK);
>          g2.drawLine(0, 0, 200, 200);
>
>         //saving thinned image onto drive
>         String temp2 = "logo thinned.jpeg";
>         File fi2 = new File("D:\\" + temp2);
>         ImageIO.write(bimg2, "jpg", fi2);
>         //g2.dispose();
>      }
>      catch (Exception e)
>      {
>          System.out.println(e);
>      }
>   }
>
>

     public static BufferedImage convertToGray(BufferedImage image) {
         BufferedImage gray = new BufferedImage(image.getWidth(),
          image.getHeight(),BufferedImage.TYPE_BYTE_GRAY);
         ColorConvertOp op = new ColorConvertOp(
          image.getColorModel().getColorSpace(),
          gray.getColorModel().getColorSpace(),null);
         op.filter(image,gray);
         return gray;
     }

You can use the same technique as above with an AffineTransformOp, as 
John Matthews mentioned, to scale an image.

-- 

Knute Johnson