一、两个三维坐标的距离

r3 =( r1 - r2) / 256
g3 = (g1 - g2) / 256
b3 = (b1 - b2) / 256

diff = sqrt(r3 r3 + g3 g3 + b3 * b3)
值越大，相似度越小；值越小，相似度越大！也可以把上面用1减去，保持值和相似度一致

百分比就是上面得到的值除以那个值的极限最大值。sqrt(r3 r3 + g3 g3 + b3 b3)/sqrt(255255+255255+255255)

二、VB参考代码

Private Function Minimum(ParamArray Vals())Dim n As Integer, MinValOn Error Resume Next MinVal = Vals(0) For n = 1 To UBound(Vals) If Vals(n) < MinVal Then MinVal = Vals(n) Next n Minimum = MinValEnd FunctionPrivate Function Maximum(ParamArray Vals())Dim n As Integer, MaxValOn Error Resume Next MaxVal = Vals(0) For n = 1 To UBound(Vals) If Vals(n) > MaxVal Then MaxVal = Vals(n) Next n Maximum = MaxValEnd FunctionPrivate Sub c2hsb(ByVal clr As Long)Dim MyR As Single, MyG As Single, MyB As SingleDim Max As Single, Min As SingleDim MyS As SingleDim Delta As Single, MyVal As SingleDim cc As String * 6Dim r1, g1, b1 As ByteOn Error Resume Next cc = Right("000000" + Hex$(clr), 6) b1 = Val("&H" + Left(cc, 2)) g1 = Val("&H" + Mid(cc, 3, 2)) r1 = Val("&H" + Right(cc, 2)) MyR = r1 / 255: MyG = g1 / 255: MyB = b1 / 255 Max = Maximum(MyR, MyG, MyB) Min = Minimum(MyR, MyG, MyB) hsbB = Int(Max * 100) If Max <> 0 Then MyS = (Max - Min) / Max * 100 Else MyS = 0 End If hsbS = MyS If hsbS = 0 Then hsbH = 0 Else Delta = Max - Min Select Case Max Case MyR MyVal = (MyG - MyB) / Delta Case MyG MyVal = 2 + (MyB - MyR) / Delta Case MyB MyVal = 4 + (MyR - MyG) / Delta End Select MyVal = MyVal * 60 If MyVal < 0 Then MyVal = MyVal + 360 hsbH = MyVal End If' Debug.Print "hsb="; hsbH; " "; hsbS; " "; hsbBEnd SubPrivate Function ColorDistance(ByVal c1 As Long, ByVal c2 As Long) As LongDim cd As LongDim h2, s1, b1, h3, s2, b2 As SingleOn Error Resume Next If c1 = -1 Or c2 = -1 Then ColorDistance = 1000000 Exit Function End If c2hsb (c1) h2 = hsbH / 360 s1 = hsbS b1 = hsbB c2hsb (c2) h3 = hsbH / 360 s2 = hsbS b2 = hsbB cd = Abs(h2 - h3) cd = cd + Abs(s1 - s2) cd = cd + Abs(b1 - b2) ColorDistance = cdEnd Function