图片滤镜 之 CoreGraphics

一、将UIImage转化为像素数据

#pragma mark - 将UIImage转化为像素数据
- (unsigned char *)convertUIImageToData:(UIImage *)image{
    CGSize size = image.size;
    
    void *data = malloc(size.width * size.height * 4);
    
    CGImageRef imageRef = [image CGImage];
    CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();//RGBA
    CGContextRef contextRef = CGBitmapContextCreate(data, size.width, size.height, 8, 4 * size.width, colorSpaceRef, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    CGContextDrawImage(contextRef, CGRectMake(0, 0, size.width, size.height), imageRef);
    
    //mrc
    CGColorSpaceRelease(colorSpaceRef);
    CGContextRelease(contextRef);
    
    return (unsigned char *)data;
}

二、对像素进行灰度处理

#pragma mark - 对像素进行灰度处理
- (unsigned char *)grayImageWithData:(unsigned char *)imageData originalImage:(UIImage *)originalImage{
    CGFloat width = originalImage.size.width;
    CGFloat height = originalImage.size.height;
    unsigned char *resultData = malloc(width * height * sizeof(unsigned char) * 4);
    
    memset(resultData, 0, sizeof(unsigned char) * 4);
    
    for (int h = 0; h < height; h++) {
        for (int w = 0; w < width; w++) {
            unsigned int imageIndex = h*width + w;
            
            unsigned char bitMapRed = *(imageData + imageIndex*4);
            unsigned char bitMapGreen = *(imageData + imageIndex*4 + 1);
            unsigned char bitMapBlue = *(imageData + imageIndex*4 + 2);
            
            int bitMap = bitMapRed * 77 / 255 + bitMapGreen * 151 / 255 + bitMapBlue * 88 / 255;
            unsigned char newBitMap = (bitMap > 255) ? 255 : bitMap;
            memset(resultData + imageIndex*4, newBitMap, 1);
            memset(resultData + imageIndex*4 + 1, newBitMap, 1);
            memset(resultData + imageIndex*4 + 2, newBitMap, 1);
            
        }
    }
    
    return resultData;
}

三、对像素进行颜色反转处理

#pragma mark - 对像素进行颜色反转处理
- (unsigned char *)reColorImageWithData:(unsigned char *)imageData originalImage:(UIImage *)originalImage{
    CGFloat width = originalImage.size.width;
    CGFloat height = originalImage.size.height;
    unsigned char *resultData = malloc(width * height * sizeof(unsigned char) * 4);
    
    memset(resultData, 0, sizeof(unsigned char) * 4);
    
    for (int h = 0; h < height; h++) {
        for (int w = 0; w < width; w++) {
            unsigned int imageIndex = h*width + w;
            
            unsigned char bitMapRed = *(imageData + imageIndex*4);
            unsigned char bitMapGreen = *(imageData + imageIndex*4 + 1);
            unsigned char bitMapBlue = *(imageData + imageIndex*4 + 2);
            unsigned char bitMapRedRe = 255 - bitMapRed;
            unsigned char bitMapGreenRe = 255 - bitMapGreen;
            unsigned char bitMapBlueRe = 255 - bitMapBlue;
            
            memset(resultData + imageIndex*4, bitMapRedRe, 1);
            memset(resultData + imageIndex*4 + 1, bitMapGreenRe, 1);
            memset(resultData + imageIndex*4 + 2, bitMapBlueRe, 1);
            
        }
    }
    
    return resultData;
}

四、将像素数据转化为UIImage

#pragma mark - 将像素数据转化为UIImage
- (UIImage *)convertDataToUIImage:(unsigned char *)imageData image:(UIImage *)imageSource{
    CGFloat width = imageSource.size.width;
    CGFloat height = imageSource.size.height;
    CGFloat dataLength = width * height * 4;
    
    CGDataProviderRef dataProviderRef = CGDataProviderCreateWithData(NULL, imageData, dataLength, NULL);
    CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
    
    CGImageRef imageRef = CGImageCreate(width, height, 8, 32, 4*width, colorSpaceRef, kCGBitmapByteOrderDefault, dataProviderRef, NULL, NO, kCGRenderingIntentDefault);
    UIImage *image = [UIImage imageWithCGImage:imageRef];
    
    //mrc
    CGImageRelease(imageRef);
    CGDataProviderRelease(dataProviderRef);
    CGColorSpaceRelease(colorSpaceRef);
    
    return image;
}

-(UIImage *)filterImage:(UIImage *)CGImage{
    
    CGImageRef imageRef = CGImage.CGImage;
    // 1 个字节 = 8bit  每行有 17152 每行有17152*8 位
    size_t width   = CGImageGetWidth(imageRef);
    size_t height  = CGImageGetHeight(imageRef);
    size_t bits    = CGImageGetBitsPerComponent(imageRef); // 8
    size_t bitsPerrow = CGImageGetBytesPerRow(imageRef); // width * bits
    
    // 颜色空间
    CGColorSpaceRef colorSpace = CGImageGetColorSpace(imageRef);
    // AlphaInfo: RGBA  AGBR  RGB  :AlphaInfo 信息
    CGImageAlphaInfo alpInfo =  CGImageGetAlphaInfo(imageRef);
    
    // bitmap的数据
    CGDataProviderRef providerRef = CGImageGetDataProvider(imageRef);
    CFDataRef bitmapData = CGDataProviderCopyData(providerRef);
    
    NSInteger pixLength = CFDataGetLength(bitmapData);
    // 像素byte数组
    Byte *pixbuf = CFDataGetMutableBytePtr((CFMutableDataRef)bitmapData);
    
    // RGBA 为一个单元
    for (int i = 0; i < pixLength; i+=4) {
        
        [self eocImageFiletPixBuf:pixbuf offset:i];
    }
    
    // 准备绘制图片了
    // bitmap 生成一个上下文  再通过上下文生成图片
    CGContextRef contextR = CGBitmapContextCreate(pixbuf, width, height, bits, bitsPerrow, colorSpace, alpInfo);
    
    CGImageRef filterImageRef = CGBitmapContextCreateImage(contextR);
    
    UIImage *filterImage =  [UIImage imageWithCGImage:filterImageRef];
    
    return filterImage;
}

// RGBA 为一个单元  彩色照变黑白照
- (void)eocImageFiletPixBuf:(Byte*)pixBuf offset:(int)offset{
    
    int offsetR = offset;
    int offsetG = offset + 1;
    int offsetB = offset + 2;
    // int offsetA = offset + 3;
    
    int red = pixBuf[offsetR];
    int gre = pixBuf[offsetG];
    int blu = pixBuf[offsetB];
    // int alp = pixBuf[offsetA];
    
    int gray = (red + gre + blu)/3;
    
    pixBuf[offsetR] = gray;
    pixBuf[offsetG] = gray;
    pixBuf[offsetB] = gray;
    
}