Question

我正在尝试申请

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3 * 3拉普拉斯滤镜用于此处著名照片的灰度版本（png扩展名）。

我主要是使用BufferedImage类来处理图像。这是拉普拉斯滤波法。

private BufferedImage measureContrast(BufferedImage image) {
        BufferedImage grayScale = createGrayscaleImage(image);
        BufferedImage copy = copyImage(grayScale);

        int width = image.getWidth();
        int height = image.getHeight();
        int sum=0;
        int a;
         //3*3 Laplacian filter (-1,-1,-1), (-1,8,-1), (-1,-1,-1)
        for(int y=1;y<height-1;y++)
            for(int x=1;x<width-1;x++) {
                sum = (-1*(grayScale.getRGB(x-1, y-1)&0xff)) + (-1*(grayScale.getRGB(x, y-1)&0xff)) + (-1*(grayScale.getRGB(x+1, y-1)&0xff))
                        + (-1*(grayScale.getRGB(x-1, y)&0xff)) + (8*(grayScale.getRGB(x,y)&0xff)) + (-1*(grayScale.getRGB(x+1, y)&0xff)) +
                        (-1*(grayScale.getRGB(x-1, y+1)&0xff)) + (-1*(grayScale.getRGB(x, y+1)&0xff)) + (-1*(grayScale.getRGB(x+1, y+1)&0xff));             
                a = ((grayScale.getRGB(x, y)>>24)&0xff);
                copy.setRGB(x, y, ((a<<24)|(sum<<16)|(sum<<8)|(sum)));
            }
return copy;

如果我运行该代码，结果就是这样

这显然是错误的。图像中突然出现粗线。

我可以确保灰度版本是正确的，因为当我在应用滤镜之前仅运行以下代码时，输出将提供完美的灰度图像。

private BufferedImage measureContrast(BufferedImage image) {
        BufferedImage grayScale = createGrayscaleImage(image);
        BufferedImage copy = copyImage(grayScale); /*rest of the code is commented*/
return copy;

我已经尝试寻找问题了几个小时，但我认为代码没有任何问题……任何见解将不胜感激。预先感谢！

为了复制图像，我使用了以下代码。我从堆栈溢出的选定答案中借用了它，因此我认为这不会错。

BufferedImage copyImage(BufferedImage bi) {
         ColorModel cm = bi.getColorModel();
         boolean isAlphaPremultiplied = cm.isAlphaPremultiplied();
         WritableRaster raster = bi.copyData(null);
         return new BufferedImage(cm, raster, isAlphaPremultiplied, null);
    }

此外，结果图像也这样打印

BufferedImage Contrast = measureContrast(image);
//write image
try {
    ImageIO.write(Contrast, "png", new File(outputPath));
    System.out.println("Printing complete");
}catch(IOException e) {
    System.out.println("File Printing Error: "+e);
}

以防万一，这是灰度图像生成方法。

private BufferedImage createGrayscaleImage(BufferedImage image) {
        int width = image.getWidth();
        int height = image.getHeight();
        BufferedImage copy = copyImage(image);

        int p=0, a=0, r=0, g=0, b=0, avg=0;
        for(int y=0;y<height;y++)
            for(int x=0;x<width;x++) {
                p=image.getRGB(x, y);
                a=(p>>24)&0xff;
                r=(p>>16)&0xff;
                g=(p>>8)&0xff;
                b=p&0xff;
                avg = (r+g+b)/3;
                p = (a<<24) | (avg<<16) | (avg<<8) | avg;
                copy.setRGB(x, y, p);
            }
        return copy;
    }

Answer 1

with open(filename,'r') as csvfile:
    csvFileReader = csv.reader(csvfile)
    for row in csvFileReader:
        dates.append(int(row[0]))
        prices.append(float(row[1]))

此方法是错误的。我应该考虑总和为负值的时间。因此，我在嵌套的for循环中添加了private BufferedImage measureContrast(BufferedImage image) { BufferedImage grayScale = createGrayscaleImage(image); BufferedImage copy = copyImage(grayScale); int width = image.getWidth(); int height = image.getHeight(); int sum=0; int a; //3*3 Laplacian filter (-1,-1,-1), (-1,8,-1), (-1,-1,-1) for(int y=1;y<height-1;y++) for(int x=1;x<width-1;x++) { sum = (-1*(grayScale.getRGB(x-1, y-1)&0xff)) + (-1*(grayScale.getRGB(x, y-1)&0xff)) + (-1*(grayScale.getRGB(x+1, y-1)&0xff)) + (-1*(grayScale.getRGB(x-1, y)&0xff)) + (8*(grayScale.getRGB(x,y)&0xff)) + (-1*(grayScale.getRGB(x+1, y)&0xff)) + (-1*(grayScale.getRGB(x-1, y+1)&0xff)) + (-1*(grayScale.getRGB(x, y+1)&0xff)) + (-1*(grayScale.getRGB(x+1, y+1)&0xff)); a = ((grayScale.getRGB(x, y)>>24)&0xff); copy.setRGB(x, y, ((a<<24)|(sum<<16)|(sum<<8)|(sum))); } return copy;，以确保在这种情况下像素值为0。

拉普拉斯过滤器产生奇怪的结果（Java）

1 个答案: