如下方法:
(下面内容要全复制)
#pragma mark - 马赛克处理
static CGContextRef CreateRGBABitmapContext (CGImageRef inImage)
{
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
void *bitmapData; //内存空间的指针，该内存空间的大小等于图像使用RGB通道所占用的字节数。
int bitmapByteCount;
int bitmapBytesPerRow;
size_t pixelsWide = CGImageGetWidth(inImage); //获取横向的像素点的个数
size_t pixelsHigh = CGImageGetHeight(inImage);
bitmapBytesPerRow = (pixelsWide * 4); //每一行的像素点占用的字节数，每个像素点的ARGB四个通道各占8个bit(0-255)的空间
bitmapByteCount = (bitmapBytesPerRow * pixelsHigh); //计算整张图占用的字节数
colorSpace = CGColorSpaceCreateDeviceRGB();//创建依赖于设备的RGB通道
//分配足够容纳图片字节数的内存空间
bitmapData = malloc( bitmapByteCount );
//创建CoreGraphic的图形上下文，该上下文描述了bitmaData指向的内存空间需要绘制的图像的一些绘制参数
context = CGBitmapContextCreate (bitmapData,pixelsWide,pixelsHigh,8,bitmapBytesPerRow,colorSpace,kCGImageAlphaPremultipliedLast);
//Core Foundation中通过含有Create、Alloc的方法名字创建的指针，需要使用CFRelease()函数释放
CGColorSpaceRelease( colorSpace );
return context;
}
static unsigned char *RequestImagePixelData(UIImage *inImage)
{
CGImageRef img = [inImage CGImage];
CGSize size = [inImage size];
//使用上面的函数创建上下文
CGContextRef cgctx = CreateRGBABitmapContext(img);
CGRect rect = {{0,0},{size.width, size.height}};
//将目标图像绘制到指定的上下文，实际为上下文内的bitmapData。
CGContextDrawImage(cgctx, rect, img);
unsigned char *data = CGBitmapContextGetData (cgctx);
//释放上面的函数创建的上下文
CGContextRelease(cgctx);
return data;
}
/*
*转换成马赛克,level代表一个点转为多少level*level的正方形
*/
+ (UIImage *)transToMosaicImage:(UIImage*)orginImage blockLevel:(NSUInteger)level
{
//获取BitmapData
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGImageRef imgRef = orginImage.CGImage;
CGFloat width = CGImageGetWidth(imgRef);
CGFloat height = CGImageGetHeight(imgRef);
CGContextRef context = CGBitmapContextCreate (nil,
width,
height,
kBitsPerComponent, //每个颜色值8bit
width*kPixelChannelCount, //每一行的像素点占用的字节数，每个像素点的ARGB四个通道各占8个bit
colorSpace,
kCGImageAlphaPremultipliedLast);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imgRef);
unsigned char *bitmapData = CGBitmapContextGetData (context);
//这里把BitmapData进行马赛克转换,就是用一个点的颜色填充一个level*level的正方形
unsigned char pixel[kPixelChannelCount] = {0};
NSUInteger index,preIndex;
for (NSUInteger i = 0; i < height - 1 ; i++) {
for (NSUInteger j = 0; j < width - 1; j++) {
index = i * width + j;
if (i % level == 0) {
if (j % level == 0) {
memcpy(pixel, bitmapData + kPixelChannelCount*index, kPixelChannelCount);
}else{
memcpy(bitmapData + kPixelChannelCount*index, pixel, kPixelChannelCount);
}
} else {
preIndex = (i-1)*width +j;
memcpy(bitmapData + kPixelChannelCount*index, bitmapData + kPixelChannelCount*preIndex, kPixelChannelCount);
}
}
}
NSInteger dataLength = width*height* kPixelChannelCount;
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, bitmapData, dataLength, NULL);
//创建要输出的图像
CGImageRef mosaicImageRef = CGImageCreate(width, height,
kBitsPerComponent,
kBitsPerPixel,
width*kPixelChannelCount ,
colorSpace,
kCGImageAlphaPremultipliedLast,
provider,
NULL, NO,
kCGRenderingIntentDefault);
CGContextRef outputContext = CGBitmapContextCreate(nil,
width,
height,
kBitsPerComponent,
width*kPixelChannelCount,
colorSpace,
kCGImageAlphaPremultipliedLast);
CGContextDrawImage(outputContext, CGRectMake(0.0f, 0.0f, width, height), mosaicImageRef);
CGImageRef resultImageRef = CGBitmapContextCreateImage(outputContext);
UIImage *resultImage = nil;
if([UIImage respondsToSelector:@selector(imageWithCGImage:scale:orientation:)]) {
// float scale = [[UIScreen mainScreen] scale];
// resultImage = [UIImage imageWithCGImage:resultImageRef scale:scale orientation:UIImageOrientationUp];
resultImage = [UIImage imageWithCGImage:resultImageRef scale:orginImage.scale orientation:orginImage.imageOrientation];
} else {
resultImage = [UIImage imageWithCGImage:resultImageRef];
}
//释放
if(resultImageRef){
CFRelease(resultImageRef);
}
if(mosaicImageRef){
CFRelease(mosaicImageRef);
}
if(colorSpace){
CGColorSpaceRelease(colorSpace);
}
if(provider){
CGDataProviderRelease(provider);
}
if(context){
CGContextRelease(context);
}
if(outputContext){
CGContextRelease(outputContext);
}
// return [[resultImage retain] autorelease];
return resultImage;
}