    import java.awt.*;
    import ij.*;
    import ij.gui.*;
    import ij.process.*;
    import ij.plugin.PlugIn;

    /** This sample ImageJ plugin generates an RGB image. */
    public class RedAndBlue_ implements PlugIn {

        public void run(String arg) {
            int w = 400, h = 400;
            ImageProcessor ip = new ColorProcessor(w, h);
            int[] pixels = (int[])ip.getPixels();
            int i = 0;
            for (int y = 0; y < h; y++) {
                int red = (y * 255) / (h - 1);
                for (int x = 0; x < w; x++) {
                    int blue = (x * 255) / (w - 1);
                    pixels[i++] = (255 << 24) | (red << 16) | blue;
                }
            }
            new ImagePlus("Red and Blue", ip).show();
        }

    }