objective-c - 如何计算RGB颜色的亮度？

Question

我有我的功能:

-(void)rgbToHSBWithR:(float)red G:(float)green B:(float)blue {

float brightness = red * 0.3 + green * 0.59 + blue * 0.11; // found in stackoverflow
NSLog(@"%f",brightness);
}

这对我不起作用。

例如:r:84 g:67 b:73。函数返回 72.760002。在 Photoshop 中，此颜色的亮度为 33%。怎么了？

谢谢。

Answer 1

使用UIColor 或NSColor:

-(void)rgbToHSBWithR:(float)red G:(float)green B:(float)blue {
    // assuming values are in 0 - 1 range, if they are byte representations, divide them by 255
    UIColor *color = [UIColor colorWithRed:red green:green blue:blue alpha:1];

    float h, s, b;
    if ([color getHue:&h saturation:&s brightness:&b alpha:NULL])
    {
        // h, s, & b now contain what you need
    }
}