[Android]-图片JNI（C++\Java）高斯模糊的实现与比较
浏览数：24 /
时间：2015年06月11日
前几天一直在弄android上的图片模糊效果的实现！
一直找不到方法，看别人说都是调用JNI，但是JNI这个东西我还真不熟悉啊！
只好从零开始了！这里不讲JNI的平台搭建，只讲JNI的关键代码，具体的项目我会共享出来给大家！
对于JNI下使用C++来模糊图片这个我真的没找到，只好自己写C++的来实现了。
在国外的一个项目中找到了一个”堆栈模糊效果“，原型如下：
// Stack Blur v1.0 // // Author: Mario Klingemann <[email protected]> // http://incubator.quasimondo.com // created Feburary 29, 2004 // 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 <[email protected]> PImage a; PImage b; void setup() { a=loadImage("dog.jpg"); size(a.width, a.height); b=new PImage(a.width, a.height); fill(255); noStroke(); frameRate(25); } void draw() { System.arraycopy(a.pixels,0,b.pixels,0,a.pixels.length); fastblur(b,mouseY/4); image(b, 0, 0); } void fastblur(PImage img,int radius){ if (radius<1){ return; } int[] pix=img.pixels; int w=img.width; int h=img.height; 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[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; 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+min(wm,max(i,0))]; sir=stack[i+radius]; sir[0]=(p & 0xff0000)>>16; sir[1]=(p & 0x00ff00)>>8; sir[2]=(p & 0x0000ff); rbs=r1-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]=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; } 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=max(0,yp)+x; sir=stack[i+radius]; sir[0]=r[yi]; sir[1]=g[yi]; sir[2]=b[yi]; rbs=r1-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]=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; } } img.updatePixels(); }
同时找到一个借鉴这个所改进后成为Java的代码，具体如下：
public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {
// 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 <[email protected]>
Bitmap bitmap;
if (canReuseInBitmap) {
bitmap = sentBitmap;
} else {
bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
}
if (radius < 1) {
return (null);
}
int w = bitmap.getWidth();
int h = bitmap.getHeight();
int[] pix = new int[w * h];
bitmap.getPixels(pix, 0, w, 0, 0, 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;
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;
}
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++) {
// Preserve alpha channel: ( 0xff000000 & pix[yi] )
pix[yi] = (0xff000000 & pix[yi]) | (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, 0, 0, w, h);
return (bitmap);
}
借鉴于此我弄了一个C的代码，基本上的整体过程都没有变化，只是改变成了C（C++也可已）的而已：
文件名：ImageBlur.c
/*************************************************
Copyright: Copyright QIUJUER 2013.
Author: Qiujuer
Date: 2014-04-18
Description:实现图片模糊处理
**************************************************/
#include<malloc.h>
#define ABS(a) ((a)<(0)?(-a):(a))
#define MAX(a,b) ((a)>(b)?(a):(b))
#define MIN(a,b) ((a)<(b)?(a):(b))
/*************************************************
Function: StackBlur(堆栈模糊)
Description: 使用堆栈方式进行图片像素模糊处理
Calls: malloc
Table Accessed: NULL
Table Updated: NULL
Input: 像素点集合，图片宽，图片高，模糊半径
Output: 返回模糊后的像素点集合
Return: 返回模糊后的像素点集合
Others: NULL
*************************************************/
static int* StackBlur(int* pix, int w, int h, int radius) {
int wm = w - 1;
int hm = h - 1;
int wh = w * h;
int div = radius + radius + 1;
int *r = (int *)malloc(wh * sizeof(int));
int *g = (int *)malloc(wh * sizeof(int));
int *b = (int *)malloc(wh * sizeof(int));
int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
int *vmin = (int *)malloc(MAX(w,h) * sizeof(int));
int divsum = (div + 1) >> 1;
divsum *= divsum;
int *dv = (int *)malloc(256 * divsum * sizeof(int));
for (i = 0; i < 256 * divsum; i++) {
dv[i] = (i / divsum);
}
yw = yi = 0;
int(*stack)[3] = (int(*)[3])malloc(div * 3 * sizeof(int));
int stackpointer;
int stackstart;
int *sir;
int rbs;
int r1 = radius + 1;
int routsum, goutsum, boutsum;
int rinsum, ginsum, binsum;
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 + (MIN(wm, MAX(i, 0)))];
sir = stack[i + radius];
sir[0] = (p & 0xff0000) >> 16;
sir[1] = (p & 0x00ff00) >> 8;
sir[2] = (p & 0x0000ff);
rbs = r1 - 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] = 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;
}
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 = MAX(0, yp) + x;
sir = stack[i + radius];
sir[0] = r[yi];
sir[1] = g[yi];
sir[2] = b[yi];
rbs = r1 - 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++) {
// Preserve alpha channel: ( 0xff000000 & pix[yi] )
pix[yi] = (0xff000000 & pix[yi]) | (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] = 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;
}
}
free(r);
free(g);
free(b);
free(vmin);
free(dv);
free(stack);
return(pix);
}在改为这个的过程中还遇到 了一个很喜剧的问题，我发现我使用这个来进行调用后结果程序内存一直增大，直到500多M，直接卡死。我知道是我写的有内存泄漏了！
然后找了一下，发现果然是。只好进行free了。然后一下就好了，发现内存占用的确比Java的要少，速度也是要快一些！
在JNI中的实现我使用了两种方案，一种是直接传递文件，一直是传递像素点集合进行模糊！分别如下：
/* * Class: com_accumulation_imageblurring_app_jni_ImageBlur * Method: blurIntArray * Signature: ([IIII)V */ JNIEXPORT void JNICALL Java_com_accumulation_imageblurring_app_jni_ImageBlur_blurIntArray (JNIEnv *, jclass, jintArray, jint, jint, jint); /* * Class: com_accumulation_imageblurring_app_jni_ImageBlur * Method: blurBitMap * Signature: (Landroid/graphics/Bitmap;I)V */ JNIEXPORT void JNICALL Java_com_accumulation_imageblurring_app_jni_ImageBlur_blurBitMap (JNIEnv *, jclass, jobject, jint);
对应的Java调用：
public class ImageBlur {
public static native void blurIntArray(int[] pImg, int w, int h, int r);
public static native void blurBitMap(Bitmap bitmap, int r);
static {
System.loadLibrary("JNI_ImageBlur");
}
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
此时我做了3种测试，一种是直接在Java层实现，一种是传递像素点集合模糊，还有就是直接传递图片进行模糊，结果如下：
通过上面的比较我们可以得出这样的结论：
1.Java的确最慢，但是其实也慢不了多少，虚拟机优化好了一样猛。
2.C中直接传递像素集合的速度最快（第一次启动）
3.在我多次切换界面后发现，直接传递像素点集合的耗时会增加，从60多到120多。
4.多次切换后发现，其实直接传递像素点的速度与传递图片过去的速度几乎一样。
5.多次操作后发现传递文件的波动较小，在100~138之间，其次是传递像素点集合的波动较大，java的波动最大！
以上就是我的结论，可能有些不正确，但是在我的机器上的确是这样！
注：勾选选择框“Downscale before blur”会先压缩图片后模糊然后放大图片，这样的情况下，模糊效果会稍微损失一些效果，但是其速度确实无法比拟的。
其耗时在：1~10ms内可运算完成。当然与你要模糊的大小有关系！
最后：项目地址：GitHub
原创作品，转载请注明出处！
QIUJUER([email protected])
郑重声明：本站内容如果来自互联网及其他传播媒体，其版权均属原媒体及文章作者所有。转载目的在于传递更多信息及用于网络分享，并不代表本站赞同其观点和对其真实性负责，也不构成任何其他建议。
