java - 如何锐化android中的图像？

Question

我想锐化图像，我的代码如下:

 public Bitmap RuiHuaBitmap(Bitmap bitmap) {
    int width, height;
    height = bitmap.getHeight();
    width = bitmap.getWidth();
    int red, green, blue;
    int a1, a2, a3, a4, a5, a6, a7, a8, a9;
    Bitmap bmpBlurred = Bitmap.createBitmap(width, height,bitmap.getConfig());

    Canvas canvas = new Canvas(bmpBlurred);

    canvas.drawBitmap(bitmap, 0, 0, null);
    for (int i = 1; i < width - 1; i++) {
        for (int j = 1; j < height - 1; j++) {

            a1 = bitmap.getPixel(i - 1, j - 1);
            a2 = bitmap.getPixel(i - 1, j);
            a3 = bitmap.getPixel(i - 1, j + 1);
            a4 = bitmap.getPixel(i, j - 1);
            a5 = bitmap.getPixel(i, j);
            a6 = bitmap.getPixel(i, j + 1);
            a7 = bitmap.getPixel(i + 1, j - 1);
            a8 = bitmap.getPixel(i + 1, j);
            a9 = bitmap.getPixel(i + 1, j + 1);

            red = (Color.red(a1) + Color.red(a2) + Color.red(a3) + Color.red(a4) + Color.red(a6) + Color.red(a7) + Color.red(a8) + Color.red(a9)) *(-1)   + Color.red(a5)*9 ;
            green = (Color.green(a1) + Color.green(a2) + Color.green(a3) + Color.green(a4) + Color.green(a6) + Color.green(a7) + Color.green(a8) + Color.green(a9)) *(-1)  + Color.green(a5)*9 ;
            blue = (Color.blue(a1) + Color.blue(a2) + Color.blue(a3) + Color.blue(a4) + Color.blue(a6) + Color.blue(a7) + Color.blue(a8) + Color.blue(a9)) *(-1)   + Color.blue(a5)*9 ;

            bmpBlurred.setPixel(i, j, Color.rgb(red, green, blue));
        }
    }
    return bmpBlurred;
}

但我无法获得理想的效果。有人可以提供更多线索，或者告诉我我的代码中有什么错误吗？

谢谢。

Answer 1

您缺少对传递给 Color.rgb() 的 rgb 值的范围检查；在调用 Color.rgb() 方法之前，您需要规范化 [0..255] 范围内的 rgb 值:

public static int rgb (int red, int green, int blue) Since: API Level 1

Return a color-int from red, green, blue components. The alpha component is implicity 255 (fully opaque). These component values should be [0..255], but there is no range check performed, so if they are out of range, the returned color is undefined. Parameters red Red component [0..255] of the color green Green component [0..255] of the color blue Blue component [0..255] of the color

您的卷积矩阵似乎适合形状变换:

 0  0  0  0  0  
 0 -1 -1 -1  0
 0 -1  9 -1  0
 0 -1 -1 -1  0 
 0  0  0  0  0

如果你觉得你的效果太强了，你也可以试试:

 0  0  0  0  0  
 0  0 -1  0  0
 0 -1  5 -1  0
 0  0 -1  0  0 
 0  0  0  0  0

作为替代