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Preston_5564C06.fm Page 193 Friday, September 23, 2005 5:13 AM

CHAPTER 6 ■ VISION 193

// calculate difference
int diff = Math.abs(srcPixel - diffPixel);
// make difference color
Color diffColor = new Color(diff, diff, diff);
// set into image
dstImg.setRGB(x, y, diffColor.getRGB());
}
}
}
// set last frame
lastImage = srcImg;
return dstImg;
}

Figure 6-12. Motion detect

Section Summary

In this section, we performed some processing and provided a mechanism to add multiple
processing operations together. The classes created in this section were

• FilterParameters: Creates a parameter object that can be passed to the ImageProcessor
• DoubleWebCamViewer: Creates a dual-view webcam that shows the original image on
one side and the processed image on the other
• ImageProcessor: The class containing all image processing code. We looked at the
following methods:
• ImageProcessor.rgbToGrey(): Converts an image to greyscale
• ImageProcessor.resize(): Resizes an image

• ImageProcessor.threshold(): Gets a greyscale color range from a minimum and
maximum value

• ImageProcessor.backgroundSubtract(): Detects motion
Next, it’s time to look at some techniques for processing color images.