if R=Ma then begin H:=del_B-del_G; end
else if G=Ma then begin H:=(1.0/3.0)+del_R-del_B; end
else if B=Ma then begin H:=(2.0/3.0)+del_G-del_R; end
end;

就是这个！！就是这个！！！！我在这上面飚了半小时

if R=Ma then begin H:=del_B-del_G; end
else if G=Ma then begin H:=(1.0/3.0)+del_R-del_B; end
else if B=Ma then begin H:=(2.0/3.0)+del_G-del_R; end
end;

if == if

begin == {
end（没分号的）== }
end;（有分号）== }

但是
示例：

if(a==b){     //<-这个就是"begin"
b=a;
}      //<-这个就是"end",没分号
else
{                                //"begin"
....
}      //<-这个就是有分号的end

所以，翻译下来就是这样

if(R==Ma){
H=del_B-del_G;
}
elseif(G==Ma){
H=(1/3)+del_R-del_B;
}
else if(B==Ma){
H=(2.0/3.0)+del_G-del_R;
}

示例：

var
a:string;
begin
a:=floattostr(360*RGB2H(strtoint(edit1.Text),strtoint(edit2.Text),strtoint(edit3.Text)));
showmessage(a);

RGB=0,0,255 ，蓝色

色轮角度就是240°：

刚看你那第一张图，，晕乎乎，纠结，，然后，终于晓得了



PS：这有什么实用性= =

图像识别
仅仅靠RGB值很难判断颜色，但是用色轮角度就可以指定一个范围内的颜色

譬如，进行颜色检出的时候，RGB模式有3个分量，而hsv模式中颜色相关分量都在H变量中了

下面两张以前截的视频中对公交车进行跟踪时就使用了H分量，进行直方图变换，归一化和逆变换后进行追踪

虽然不是很明白你在说什么  但是知道用处了

刚才写验证码识别，用到了HSL。翻译成XXXXXT了

正好放上来

    Public Function Min(ByVal a As Double, ByVal b As Double) As Double
        If a < b Then
            Return a
        Else
            Return b
        End If
    End Function

    Public Function Max(ByVal a As Double, ByVal b As Double) As Double
        If a > b Then
            Return a
        Else
            Return b
        End If
    End Function

    Public Function RGB2H(ByVal r As Double, ByVal g As Double, ByVal b As Double) As Double
        Dim mi, ma As Double
        Dim del_r, del_g, del_b, del_max As Double
        Dim h As Double

        r = r / 255
        g = g / 255
        b = b / 255

        mi = Min(r, Min(g, b))
        ma = Max(r, Max(g, b))
        del_max = ma - mi

        If del_max = 0 Then
            h = 0
        Else
            del_r = ((ma - r / 6.0) + (del_max / 2.0)) / del_max
            del_g = ((ma - g / 6.0) + (del_max / 2.0)) / del_max
            del_b = ((ma - b / 6.0) + (del_max / 2.0)) / del_max



            If r = ma Then
                h = del_b - del_g
            Else
                If g = ma Then
                    h = (1.0 / 3.0) + del_r - del_b
                Else
                    If b = ma Then
                        h = (2.0 / 3.0) + del_g - del_r
                    End If
                End If
            End If

            If h < 0 Then h = h + 1
            If h > 1 Then h = h - 1

        End If
        Return h
    End Function