Learning Java, 4th Edition

Filtering Image Data

An image filter is an object that performs transformations on image data. The Java 2D API supports image filtering through the BufferedImageOp interface. An image filter takes a BufferedImage as input (the source image) and performs some processing on the image data, producing another BufferedImage (the destination image).

The 2D API comes with a handy toolbox of BufferedImageOp implementations, as summarized in Table 21-1.

Table 21-1. Image operators in the 2D API

Name	Description
AffineTransformOp	Transforms an image geometrically
ColorConvertOp	Converts from one color space to another
ConvolveOp	Performs a convolution, a mathematical operation that can be used to blur, sharpen, or otherwise process an image
LookupOp	Uses one or more lookup tables to process image values
RescaleOp	Uses multiplication to process image values

Let’s take a look at two of the simpler image operators. First, try the following application. It loads an image (the first command-line argument is the filename) and processes it in different ways as you select items from the combo box. The application is shown in Figure 21-6.

Figure 21-6. The ImageProcessor application

Here’s the source code:

    //file: ImageProcessor.java
    import java.awt.*;
    import java.awt.event.*;
    import java.awt.geom.*;
    import java.awt.image.*;
    import javax.swing.*;

    public class ImageProcessor extends JComponent {
      private ...