快速在android中可变模糊或模糊库

Question

最近，我尝试blur图像，半径是可变的。我试图实现它myseft，但它看起来很慢。在这个网站上，我得到了一个名为stack blur的快速模糊方法：

  static Bitmap fastblur(Bitmap sentBitmap, int radius, int fromX, int fromY,
        int width, int height) {

    // Stack Blur v1.0 from
    // http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
    //
    // Java Author: Mario Klingemann <mario at quasimondo.com>
    // http://incubator.quasimondo.com
    // created Feburary 29, 2004
    // Android port : Yahel Bouaziz <yahel at kayenko.com>
    // http://www.kayenko.com
    // ported april 5th, 2012

    // This is a compromise between Gaussian Blur and Box blur
    // It creates much better looking blurs than Box Blur, but is
    // 7x faster than my Gaussian Blur implementation.
    //
    // I called it Stack Blur because this describes best how this
    // filter works internally: it creates a kind of moving stack
    // of colors whilst scanning through the image. Thereby it
    // just has to add one new block of color to the right side
    // of the stack and remove the leftmost color. The remaining
    // colors on the topmost layer of the stack are either added on
    // or reduced by one, depending on if they are on the right or
    // on the left side of the stack.
    //
    // If you are using this algorithm in your code please add
    // the following line:
    //
    // Stack Blur Algorithm by Mario Klingemann <mario@quasimondo.com>

    Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);

    if (radius < 1) {
        return (null);
    }

    int w = width;
    int h = height;

    int[] pix = new int[w * h];

    bitmap.getPixels(pix, 0, w, fromX, fromY, w, h);

    int wm = w - 1;
    int hm = h - 1;
    int wh = w * h;
    int div = radius + radius + 1;

    int r[] = new int[wh];
    int g[] = new int[wh];
    int b[] = new int[wh];
    int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
    int vmin[] = new int[Math.max(w, h)];

    int divsum = (div + 1) >> 1;
    divsum *= divsum;
    int dv[] = new int[256 * divsum];
    for (i = 0; i < 256 * divsum; i++) {
        dv[i] = (i / divsum);
    }

    yw = yi = 0;

    int[][] stack = new int[div][3];
    int stackpointer;
    int stackstart;
    int[] sir;
    int rbs;
    int r1 = radius + 1;
    int routsum, goutsum, boutsum;
    int rinsum, ginsum, binsum;

    int originRadius = radius;
    for (y = 0; y < h; y++) {
        rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
        for (i = -radius; i <= radius; i++) {
            p = pix[yi + Math.min(wm, Math.max(i, 0))];
            sir = stack[i + radius];
            sir[0] = (p & 0xff0000) >> 16;
            sir[1] = (p & 0x00ff00) >> 8;
            sir[2] = (p & 0x0000ff);
            rbs = r1 - Math.abs(i);
            rsum += sir[0] * rbs;
            gsum += sir[1] * rbs;
            bsum += sir[2] * rbs;
            if (i > 0) {
                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];
            } else {
                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];
            }
        }
        stackpointer = radius;

        for (x = 0; x < w; x++) {

            r[yi] = dv[rsum];
            g[yi] = dv[gsum];
            b[yi] = dv[bsum];

            rsum -= routsum;
            gsum -= goutsum;
            bsum -= boutsum;

            stackstart = stackpointer - radius + div;
            sir = stack[stackstart % div];

            routsum -= sir[0];
            goutsum -= sir[1];
            boutsum -= sir[2];

            if (y == 0) {
                vmin[x] = Math.min(x + radius + 1, wm);
            }
            p = pix[yw + vmin[x]];

            sir[0] = (p & 0xff0000) >> 16;
            sir[1] = (p & 0x00ff00) >> 8;
            sir[2] = (p & 0x0000ff);

            rinsum += sir[0];
            ginsum += sir[1];
            binsum += sir[2];

            rsum += rinsum;
            gsum += ginsum;
            bsum += binsum;

            stackpointer = (stackpointer + 1) % div;
            sir = stack[(stackpointer) % div];

            routsum += sir[0];
            goutsum += sir[1];
            boutsum += sir[2];

            rinsum -= sir[0];
            ginsum -= sir[1];
            binsum -= sir[2];

            yi++;
        }
        yw += w;
    }

    radius = originRadius;

    for (x = 0; x < w; x++) {
        rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
        yp = -radius * w;
        for (i = -radius; i <= radius; i++) {
            yi = Math.max(0, yp) + x;

            sir = stack[i + radius];

            sir[0] = r[yi];
            sir[1] = g[yi];
            sir[2] = b[yi];

            rbs = r1 - Math.abs(i);

            rsum += r[yi] * rbs;
            gsum += g[yi] * rbs;
            bsum += b[yi] * rbs;

            if (i > 0) {
                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];
            } else {
                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];
            }

            if (i < hm) {
                yp += w;
            }
        }
        yi = x;
        stackpointer = radius;
        for (y = 0; y < h; y++) {
            pix[yi] = 0xff000000 | (dv[rsum] << 16) | (dv[gsum] << 8)
                    | dv[bsum];

            rsum -= routsum;
            gsum -= goutsum;
            bsum -= boutsum;

            stackstart = stackpointer - radius + div;
            sir = stack[stackstart % div];

            routsum -= sir[0];
            goutsum -= sir[1];
            boutsum -= sir[2];

            if (x == 0) {
                vmin[y] = Math.min(y + r1, hm) * w;
            }
            p = x + vmin[y];

            sir[0] = r[p];
            sir[1] = g[p];
            sir[2] = b[p];

            rinsum += sir[0];
            ginsum += sir[1];
            binsum += sir[2];

            rsum += rinsum;
            gsum += ginsum;
            bsum += binsum;

            stackpointer = (stackpointer + 1) % div;
            sir = stack[stackpointer];

            routsum += sir[0];
            goutsum += sir[1];
            boutsum += sir[2];

            rinsum -= sir[0];
            ginsum -= sir[1];
            binsum -= sir[2];

            yi += w;
        }
    }

    bitmap.setPixels(pix, 0, w, fromX, fromY, w, h);

    return (bitmap);
}

实际上，我希望这种模糊方法可以变化模糊（例如：当图像中心的距离减小时，半径也会减小）。但是，我不擅长移位，我修改这些代码太难了！ 所以，我想问一种方法来实现像径向模糊这样的代码！我想知道是否有任何模糊库包含径向模糊，灰度，....在Android！如果有人能帮助我，真的很感激！谢谢你！

Answer 1

由于其对速度的优化，该算法不适合适应变化的半径。如果你采取不同的方法，你仍然可以使用它：

原则是您创建多个临时地图，每个临时地图具有增加的（均匀）模糊半径，然后根据该点的半径应该将它们中的两个混合在一起。假设您准备3个临时地图，一个半径为4，一个为8，另一个为16.现在您希望一个像素的模糊半径为12。你做的是将地图2和3混合约50％。您使用的临时地图越多，质量越好，但3（加上原始的不模糊地图）通常就足够了。

我在我的复合模糊画布中使用这种技术：http://www.quasimondo.com/CompoundBlurForCanvas/CompoundBlurDemo.html - 这可以让你做倾斜移位效果或晕影。

如果您正在寻找看起来更像是相机缩放效果的径向模糊，则必须使用不同的方法。在这种情况下，您首先将位图从笛卡尔映射转换为极坐标映射，然后进行水平模糊，最后将地图转换回笛卡尔空间 - 我的网站上有一个Flash演示和一些源代码，也有更详细的解释：http://www.quasimondo.com/archives/000697.php

Answer 2

如何使用滑块实现复合模糊：

/// HTML ///

//使用：CompoundBlur.js //

<DIV CLASS="specimenWindow">

    <DIV CLASS="specimenImage">

        <IMG ID="specImg" WIDTH="150" HEIGHT="150" />
        <CANVAS ID="specCanvas" WIDTH="150" HEIGHT="150"></CANVAS>

    </DIV>

</DIV>

<SCRIPT TYPE="text/javascript" SRC="js/CompoundBlur.js"></SCRIPT>

/// CSS ///

.specimenWindow {
    position: absolute;
    width: 150px;
    height: 150px;
    left: 37px;
    top: 96px;
}

.specimenImage {
    height: 150px;
    width: 150px;
}

#specCanvas {
    position: absolute;
    top: 27px;
    left: 2px;
}

/// JS ///

var specImg = document.getElementById("specImg");

_slider.ontouchend = function() {
    compoundBlur();
} 

function compoundBlur() {
    var lensRead = _slider.getPosition(0, 80);
    var rData = getRadialGradientMap( 150, 150, 75, 75, 25, 60 ); 
    compoundBlurImage( "specImg", "specCanvas", rData, lensRead, 1.5, 2, true );
}

所以，只需调整数值即可获得更流畅的模糊效果，当我的滑块完成触摸时，我会让它变得模糊，这在移动设备上更有效，而滑块更改时会不断模糊，否则iPad会获得温暖并开始迅速耗尽电池电量

所以希望能帮助任何人尝试实现快速复合模糊。