How to realize the gray function of QQ avatar?

Use Sdwebimage to load a picture, and then call the Gray method

[_iconimageview sd_setimagewithurl:[nsurl URLWithString:orderItems.iconUrl] Placeholderimage:[uiimage imagenamed:@ "Home_root_headimage"] completed:^ (UIImage *image, Nserror *error, Sdimagecachetype cachetype, Nsurl *imageURL) {

UIImage *grayimage = [self converttograyscalewith:image];

if (grayimage) {

_iconimageview.image = Grayimage;

} else {

_iconimageview.image = [UIImage imagenamed:@ "Home_root_headimage"];

}

}];

Methods of ash-induced function

-(UIImage *) Converttograyscalewith: (UIImage *) Scousimage {

Cgsize size = [scousimage size];

int width = size.width;

int height = size.height;

The pixels'll is painted to this array

uint32_t *pixels = (uint32_t *) malloc (width * height * sizeof (uint32_t));

Clear the pixels so any transparency is preserved

memset (pixels, 0, Width * height * sizeof (uint32_t));

Cgcolorspaceref colorspace = Cgcolorspacecreatedevicergb ();

Create a context with RGBA pixels

Cgcontextref context = cgbitmapcontextcreate (pixels, width, height, 8, Width * sizeof (uint32_t), ColorSpace,

Kcgbitmapbyteorder32little | Kcgimagealphapremultipliedlast);

Paint the bitmap to our context which would fill in the pixels array

Cgcontextdrawimage (context, CGRectMake (0, 0, width, height), [scousimage cgimage]);

for (int y = 0; y < height; y++) {

for (int x = 0; x < width; + +) {

uint8_t *rgbapixel = (uint8_t *) &pixels[y * width + x];

Convert to grayscale using recommended Method:http://en.wikipedia.org/wiki/grayscale#converting_color_to_grayscale

uint32_t Gray = 0.3 * rgbapixel[red] + 0.59 * Rgbapixel[green] + 0.11 * Rgbapixel[blue];

Set the pixels to gray

Rgbapixel[red] = Gray;

Rgbapixel[green] = Gray;

Rgbapixel[blue] = Gray;

}

}

Create a new cgimageref from our context with the modified pixels

Cgimageref image = Cgbitmapcontextcreateimage (context);

We ' re do with the context, color space, and pixels

Cgcontextrelease (context);

Cgcolorspacerelease (ColorSpace);

Free (pixels);

Make a new UIImage to return

UIImage *resultuiimage = [UIImage imagewithcgimage:image];

We ' re done with the image now too

Cgimagerelease (image);

return resultuiimage;

}

How to realize the gray function of QQ avatar?