ios获得UIImage的主色调方法

来源：互联网发布：05~06赛季科比数据编辑：程序博客网时间：2024/05/24 06:49

网络上有一个算法，但是经过测试误差比较，经过我的完善和修改，误差比较小了，消耗时间差不多，网上的算法的地址：

http://www.cocoachina.com/bbs/read.php?tid=181490 点击打开链接

我自己的修改算法如下：

static void RGBtoHSV( float r, float g, float b, float *h, float *s, float *v ){    float min, max, delta;    min = MIN( r, MIN( g, b ));    max = MAX( r, MAX( g, b ));    *v = max;               // v    delta = max - min;    if( max != 0 )        *s = delta / max;       // s    else {        // r = g = b = 0        // s = 0, v is undefined        *s = 0;        *h = -1;        return;    }    if( r == max )        *h = ( g - b ) / delta;     // between yellow & magenta    else if( g == max )        *h = 2 + ( b - r ) / delta; // between cyan & yellow    else        *h = 4 + ( r - g ) / delta; // between magenta & cyan    *h *= 60;               // degrees    if( *h < 0 )        *h += 360;}@implementation CMUIImageManager-(UIColor*)mostColor:(UIImage*)image{        #if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_6_1    int bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;#else    int bitmapInfo = kCGImageAlphaPremultipliedLast;#endif        //第一步 先把图片缩小 加快计算速度. 但越小结果误差可能越大    CGSize thumbSize=CGSizeMake(40, 40);        CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    CGContextRef context = CGBitmapContextCreate(NULL,                                                 thumbSize.width,                                                 thumbSize.height,                                                 8,//bits per component                                                 thumbSize.width*4,                                                 colorSpace,                                                 bitmapInfo);        CGRect drawRect = CGRectMake(0, 0, thumbSize.width, thumbSize.height);    CGContextDrawImage(context, drawRect, image.CGImage);    CGColorSpaceRelease(colorSpace);                //第二步 取每个点的像素值    unsigned char* data = CGBitmapContextGetData (context);        if (data == NULL) return nil;    NSArray *MaxColor=nil;   // NSCountedSet *cls=[NSCountedSet setWithCapacity:thumbSize.width*thumbSize.height];    float maxScore=0;    for (int x=0; x<thumbSize.width*thumbSize.height; x++) {                             int offset = 4*x;                        int red = data[offset];            int green = data[offset+1];            int blue = data[offset+2];            int alpha =  data[offset+3];                        if (alpha<25)continue;                        float h,s,v;            RGBtoHSV(red, green, blue, &h, &s, &v);                        float y = MIN(abs(red*2104+green*4130+blue*802+4096+131072)>>13, 235);            y= (y-16)/(235-16);            if (y>0.9) continue;                    float score = (s+0.1)*x;            if (score>maxScore) {                maxScore = score;            }           MaxColor=@[@(red),@(green),@(blue),@(alpha)];            //[cls addObject:clr];                                   }    CGContextRelease(context);        return [UIColor colorWithRed:([MaxColor[0] intValue]/255.0f) green:([MaxColor[1] intValue]/255.0f) blue:([MaxColor[2] intValue]/255.0f) alpha:([MaxColor[3] intValue]/255.0f)];}

是按照饱和度来计算的，误差要小些

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