获取UIImage像素数据

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typedef CF_ENUM(uint32_t, CGImageAlphaInfo) {
kCGImageAlphaNone, /* For example, RGB. */
kCGImageAlphaPremultipliedLast, /* For example, premultiplied RGBA */
kCGImageAlphaPremultipliedFirst, /* For example, premultiplied ARGB */
kCGImageAlphaLast, /* For example, non-premultiplied RGBA */
kCGImageAlphaFirst, /* For example, non-premultiplied ARGB */
kCGImageAlphaNoneSkipLast, /* For example, RBGX. */
kCGImageAlphaNoneSkipFirst, /* For example, XRGB. */
kCGImageAlphaOnly /* No color data, alpha data only */
};

//Create a bitmap context

CG_EXTERN CGContextRef CGBitmapContextCreate(

void *data,//如果data非空，指向一个内存区域，大小至少bytesPerRow *height的字节。如果data为空,data上下文自动分配和释放收回。

size_t width,//像素宽

size_t height,//像素高

size_t bitsPerComponent, //位的数量为每个组件的指定一个像素

size_t bytesPerRow,//每一行的位图的字节,至少要宽*每个像素的字节

CGColorSpaceRef space, //指定一个颜色空间

CGBitmapInfo bitmapInfo//指定位图是否应该包含一个alpha通道和它是如何产生的,以及是否组件是浮点或整数

)

//获取UIImage像素ARGB值

- (unsigned char *)getImageData:(UIImage*)image

{

CGImageRef imageref = [image CGImage];
CGColorSpaceRef colorspace=CGColorSpaceCreateDeviceRGB();

int width=CGImageGetWidth(imageref);
int height=CGImageGetHeight(imageref);
int bytesPerPixel=4;
int bytesPerRow=bytesPerPixel*width;
int bitsPerComponent = 8;

unsigned char * imagedata=malloc(width*height*bytesPerPixel);

CGContextRef cgcnt =CGBitmapContextCreate(imagedata,
width,
height,
bitsPerComponent,
bytesPerRow,
colorspace,
kCGImageAlphaPremultipliedFirst);
//将图像写入一个矩形
CGRect therect = CGRectMake(0, 0, width, height);
CGContextDrawImage(cgcnt, therect, imageref);

//释放资源
CGColorSpaceRelease(colorspace);

CGContextRelease(cgcnt);

for (int i = 0 ; i < 4*width*height; i++) {
NSLog(@"UIImage(%d,%d) == %d",(i/4)%width,(i/4)/width,imagedata[i]);
if (i%4==3) {
NSLog(@"=================");
}
}

return imagedata;
}

//获取UIImage像素Gray值

- (unsigned char *)getImageData:(UIImage*)image

{

CGImageRef imageref = [image CGImage];

CGColorSpaceRef colorspace=CGColorSpaceCreateDeviceGray();

   int width=CGImageGetWidth(imageref);
   int height=CGImageGetHeight(imageref);
   int bytesPerPixel=1;
   int bytesPerRow=bytesPerPixel*width;
   int bitsPerComponent = 8;

unsigned char * imagedata=malloc(width*height*bytesPerPixel);

CGContextRef cgcnt = CGBitmapContextCreate(imagedata,
width,
height,
bitsPerComponent,
bytesPerRow,
colorspace,
kCGImageAlphaNone);
   //将图像写入一个矩形
   CGRect therect = CGRectMake(0, 0, width, height);
   CGContextDrawImage(cgcnt, therect, imageref);

//释放资源
CGColorSpaceRelease(colorspace);

CGContextRelease(cgcnt);

   for (int i = 0 ; i < width*height; i++) {
   NSLog(@"UIImage(%d,%d) == %d", i%width, i/width, imagedata[i]);
}

return imagedata;
}

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