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Preston_5564C06.fm Page 189 Friday, September 23, 2005 5:13 AM

CHAPTER 6 ■ VISION 189

return new Color(gray, gray, gray);
}

//return greyscale equivalent of pixel as int
public int getGrey(int colorInt) {
return getGrey(new Color(colorInt)).getRed();
}

Figure 6-9. A color image converted to GreyScale

One of the things you might notice from the last example is that iterating through 320×240
pixels might be really fast for converting to grey, but not if you’re using a few different filters
and hope to maintain your desired frame rate. Currently, it takes about 63 milliseconds from
the start of this method to the end. Since the frame rate is 15 frames per second, the maximum
processing time per frame is 67 milliseconds. We’re getting close. If I add a 10-millisecond
pause in the middle, I’d notice the frame-rate decrease. We can get around this by resizing the
image. By resizing the image from 320×240 to 160×120, the time to process the image is reduced
by four to about 15 milliseconds.

Code Objective

The objective in this example is to resize an image.

Code Discussion
This uses the java.awt.Graphics2D class. First, we create a destination image. Second, we give
the class rendering hints on how to render the new image. Third, we draw the new, scaled
version of the image using the AffineTransformation class. Finally, we return the new image.
You can see the results of Example 6-13 in Figure 6-10.

■Note You’ll see in later sections that if we iterate through all the pixels of an image, resizing them by
one-half, it will improve the performance of our algorithm by a minimum of 400 percent.