Question

在Picture类的主体中创建一个名为“specialEffect”的新公共方法，该方法的返回类型为void，并且不带参数。该方法应包含四个循环，每个循环遍历图像的像素，使得每个循环遍历总像素数的1/4并执行不同的效果，如下所示：第一个循环是应用一种效果，该效果从每个像素中移除蓝色和绿色分量，使红色分量保持不变。从最后一个离开的位置继续的下一个循环是从每个像素中移除蓝色和红色分量，使绿色分量保持不变。下一个循环从最后一个离开它的位置继续，以从每个像素中移除绿色和红色分量，使蓝色分量保持不变。最后一个循环从最后一个关闭的位置开始，将每个像素转换为灰度。

我该怎么做呢？我只知道如何将它分成两半并改变顶部..不知道如何去做部分。

谢谢！

Answer 1

下面的代码生成了这张图片：

screenshot

private static BufferedImage specialEffect(BufferedImage in) {

    BufferedImage out = new BufferedImage(in.getWidth(), in.getHeight(), 
            BufferedImage.TYPE_INT_ARGB);

    for (int x = 0; x < out.getWidth() / 2; x++) {
        for (int y = 0; y < out.getHeight() / 2; y++) {
            Color c = new Color(in.getRGB(x, y));
            out.setRGB(x, y, new Color(c.getRed(), 0, 0).getRGB());
        }
    }
    for (int x = out.getWidth() / 2; x < out.getWidth(); x++) {
        for (int y = 0; y < out.getHeight() / 2; y++) {
            Color c = new Color(in.getRGB(x, y));
            out.setRGB(x, y, new Color(0, c.getGreen(), 0).getRGB());
        }
    }
    for (int x = 0; x < out.getWidth() / 2; x++) {
        for (int y = out.getHeight() / 2; y < out.getHeight(); y++) {
            Color c = new Color(in.getRGB(x, y));
            out.setRGB(x, y, new Color(0, 0, c.getBlue()).getRGB());
        }
    }
    for (int x = out.getWidth() / 2; x < out.getWidth(); x++) {
        for (int y = out.getHeight() / 2; y < out.getHeight(); y++) {
            Color c = new Color(in.getRGB(x, y));
            int m = Math.max(c.getRed(),Math.max(c.getGreen(),c.getBlue()));
            out.setRGB(x, y, new Color(m, m, m).getRGB());
        }
    }

    return out;
}

public static void main(String[] args) throws IOException {
    JFrame frame = new JFrame("Test");

    frame.add(new JComponent() {

         BufferedImage image = specialEffect(ImageIO.read(new URL("http://upload.wikimedia.org/wikipedia/en/2/24/Lenna.png")));

         @Override
         protected void paintComponent(Graphics g) {
              super.paintComponent(g);
              g.drawImage(image, 0, 0, this);
         }
    });

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 400);
    frame.setVisible(true);
}

Answer 2

我假设你的Picture类有以下方法：

int getNumberOfPixels()
float getRValueOfNthPixel(int n)
float getGValueOfNthPixel(int n)
float getBValueOfNthPixel(int n)
void setRValueOfNthPixel(int n, float r)
void setGValueOfNthPixel(int n, float g)
void setBValueOfNthPixel(int n, float b)

如果像素数总是4的倍数，那么“specialEffect”方法的一种可能实现方式是：

public void specialEffect() {
    int n = getNumberOfPixels();
    int limit1 = 1 * n / 4;
    int limit2 = 2 * n / 4;
    int limit3 = 3 * n / 4;
    int limit4 = 4 * n / 4;

    /*
     * The first loop is to apply an effect that removes the both the blue
     * and green component from each pixel leaving the red component
     * unchanged.
     */
    for (int i = 0; i < limit1; i++) {
        setBValueOfNthPixel(i, 0);
        setGValueOfNthPixel(i, 0);
    }

    /*
     * The next loop continuing from where the last left off is to remove
     * the blue and red component from each pixel leaving the green
     * component unchanged.
     */
    for (int i = limit1; i < limit2; i++) {
        setBValueOfNthPixel(i, 0);
        setRValueOfNthPixel(i, 0);
    }

    /*
     * The next loop continuing from where the last left off it to remove
     * the green and red component from each pixel leaving the blue 
     * component unchanged.
     */
    for (int i = limit2; i < limit3; i++) {
        setGValueOfNthPixel(i, 0);
        setRValueOfNthPixel(i, 0);
    }

    /*
     * The final loop continuing from where the last off is to convert each
     * pixel to greyscale.
     */
    for (int i = limit3; i < limit4; i++) {
        float grayValue = (getRValueOfNthPixel(i)
                + getGValueOfNthPixel(i)
                + getBValueOfNthPixel(i)) / 3;
        setRValueOfNthPixel(i, grayValue);
        setGValueOfNthPixel(i, grayValue);
        setBValueOfNthPixel(i, grayValue);
    }
}

如何将图片分成4个部分并更改每个部分？

2 个答案: