UIImage+CNGray.m
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//
// UIImage+CNGray.m
// CNLiveScioLive
//
// Created by CNLive on 2021/4/27.
// Copyright © 2021 CNLive. All rights reserved.
//
#import "UIImage+CNGray.h"
@implementation UIImage (CNGray)
+ ( UIImage *)grayImage:( UIImage *)sourceImage {
const int RED = 1;
const int GREEN = 2;
const int BLUE = 3;
CGRect imageRect = CGRectMake(0, 0, sourceImage.size.width *sourceImage.scale, sourceImage.size.height *sourceImage.scale);
int width = imageRect.size.width;
int height = imageRect.size.height;
uint32_t *pisels = (uint32_t *)malloc(width*height *sizeof(uint32_t));
memset(pisels, 0, width *height *sizeof(uint32_t));
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pisels, width, height, 8, width *sizeof(uint32_t), colorSpace, kCGBitmapByteOrder32Little|kCGImageAlphaPremultipliedLast);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), [sourceImage CGImage]);
for (int y = 0; y < height; y ++) {
for (int x = 0; x<width; x++) {
uint8_t *rgbaPixel = (uint8_t *)&pisels[y*width +x];
uint32_t gray = 0.3 *rgbaPixel[RED] + 0.59 *rgbaPixel[GREEN] + 0.11 *rgbaPixel[BLUE];
rgbaPixel[RED] = gray;
rgbaPixel[GREEN] = gray;
rgbaPixel[BLUE] = gray;
}
}
CGImageRef imageRef = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
free(pisels);
UIImage *resultImage = [UIImage imageWithCGImage:imageRef scale:sourceImage.scale orientation:UIImageOrientationUp];
CGImageRelease(imageRef);
return resultImage;
}
@end