UIImage获取灰度图像

#import <UIKit/UIKit.h>

@interface UIImage(grayImage)

-(UIImage*)getGrayImage;

@end

#import "UIImage+grayImage.h"

@implementation UIImage(grayImage)

-(UIImage*)getGrayImage{

    int width =self.size.width;

    int height =self.size.height;

    CGColorSpaceRef colorSpace =CGColorSpaceCreateDeviceGray();

    CGContextRef context =CGBitmapContextCreate (nil,width,height,8,0,colorSpace,kCGImageAlphaNone);

    CGColorSpaceRelease(colorSpace);

    if (context ==NULL) {

        returnnil;

    }

    CGContextDrawImage(context,CGRectMake(0,0, width, height), self.CGImage);

    UIImage *grayImage = [UIImageimageWithCGImage:CGBitmapContextCreateImage(context)];

    CGContextRelease(context);

    return grayImage;

}

@end