在RGB和HSB颜色值之间切换的算法
我阅读了文章算法切换RGB和HSB颜色值
Type RGBColor Red As Byte Green As Byte Blue As Byte End Type Type HSBColor Hue As Double Saturation As Double Brightness As Double End Type Function RGBToHSB(rgb As RGBColor) As HSBColor Dim minRGB, maxRGB, Delta As Double Dim h, s, b As Double h = 0 minRGB = Min(Min(rgb.Red, rgb.Green), rgb.Blue) maxRGB = Max(Max(rgb.Red, rgb.Green), rgb.Blue) Delta = (maxRGB - minRGB) b = maxRGB If (maxRGB 0) Then s = 255 * Delta / maxRGB Else s = 0 End If If (s 0) Then If rgb.Red = maxRGB Then h = (CDbl(rgb.Green) - CDbl(rgb.Blue)) / Delta Else If rgb.Green = maxRGB Then h = 2 + (CDbl(rgb.Blue) - CDbl(rgb.Red)) / Delta Else If rgb.Blue = maxRGB Then h = 4 + (CDbl(rgb.Red) - CDbl(rgb.Green)) / Delta End If End If End If Else h = -1 End If h = h * 60 If h 3 Then HSBToRGB.Blue = CByte(Round(maxRGB)) If h > 4 Then HSBToRGB.Green = CByte(Round(maxRGB - Delta)) HSBToRGB.Red = CByte(Round((h - 4) * Delta)) + HSBToRGB.Green Else HSBToRGB.Red = CByte(Round(maxRGB - Delta)) HSBToRGB.Green = CByte(HSBToRGB.Red - Round((h - 4) * Delta)) End If Else If h > 1 Then HSBToRGB.Green = CByte(Round(maxRGB)) If h > 2 Then HSBToRGB.Red = CByte(Round(maxRGB - Delta)) HSBToRGB.Blue = CByte(Round((h - 2) * Delta)) + HSBToRGB.Red Else HSBToRGB.Blue = CByte(Round(maxRGB - Delta)) HSBToRGB.Red = CByte(HSBToRGB.Blue - Round((h - 2) * Delta)) End If Else If h > -1 Then HSBToRGB.Red = CByte(Round(maxRGB)) If h > 0 Then HSBToRGB.Blue = CByte(Round(maxRGB - Delta)) HSBToRGB.Green = CByte(Round(h * Delta)) + HSBToRGB.Blue Else HSBToRGB.Green = CByte(Round(maxRGB - Delta)) HSBToRGB.Blue = CByte(HSBToRGB.Green - Round(h * Delta)) End If End If End If End If End If End Function 然后有人发布了一个错误，但没有详细说明
但我认为当h大于5时需要管理，例如颜色R：130 G：65 B：111
If h > 5 Then HSBToRGB.Red = CByte(Round(maxRGB)) If h > 6 Then HSBToRGB.Blue= CByte(Round(maxRGB - Delta)) HSBToRGB.Green= CByte(Round((h - 6) * Delta)) HSBToRGB.Blue Else HSBToRGB.Green= CByte(Round(maxRGB - Delta)) HSBToRGB.Blue = CByte(HSBToRGB.Green- Round((h - 6) * Delta)) End If
我需要添加那段代码吗？ 我认为它应该进入HSB到RGB（在我的C＃转换中）
... if (s != 0) { delta = s * maxRGB / 255; if (h > 5) rgb.Red = Convert.ToByte(Math.Round(maxRGB)); if (h > 6) { rgb.Green = Convert.ToByte(Math.Round(maxRGB - delta)); rgb.Blue = Convert.ToByte(rgb.Green - Math.Round((h - 6) * delta)); } if (h > 3) { ...
如果它像上面那样，或者
if (h > 6) { } else if (h > 3) { }
使用.NET的Color对象中内置的方法是不可能的，因为正如几个答案所指出的那样，它们不支持反向（将HSB颜色转换为RGB）。 此外， Color.GetBrightness实际上返回亮度 ，而不是亮度/值。 由于HSB / HSV和HSL颜色空间的相似性（ 维基百科 ），因此存在很多混淆。 我看到很多颜色选择器最终使用了错误的算法和/或模型。
在给出RGB颜色的情况下，原始代码在我计算色调值时错过了一些可能的场景。 对我来说，按照你正在考虑的代码来添加它有点困难，但是第一件事就是跳出来（并且你似乎没有暗示修正）是当饱和度= 0时，你设置色调为-1。 当您稍后将色调乘以60时，最终得到-60，然后将其添加到360（ If h < 0 Then h = h + 360 ），产生300的结果，这是不正确的。
我使用以下代码（在VB.NET中）在RGB和HSB（我称之为HSV）之间进行转换。 结果已经过非常广泛的测试，结果几乎与Photoshop的颜色选择器相同（除了它对颜色配置文件的补偿）。 发布代码和我的代码之间的主要区别（除了计算色调的重要部分之外）是我更喜欢将RGB值归一化到0到1之间来进行计算，而不是使用0到255之间的原始值。这消除了您发布的原始代码中的一些低效率和多次转换。
Public Function RGBtoHSV(ByVal R As Integer, ByVal G As Integer, ByVal B As Integer) As HSV ''# Normalize the RGB values by scaling them to be between 0 and 1 Dim red As Decimal = R / 255D Dim green As Decimal = G / 255D Dim blue As Decimal = B / 255D Dim minValue As Decimal = Math.Min(red, Math.Min(green, blue)) Dim maxValue As Decimal = Math.Max(red, Math.Max(green, blue)) Dim delta As Decimal = maxValue - minValue Dim h As Decimal Dim s As Decimal Dim v As Decimal = maxValue ''# Calculate the hue (in degrees of a circle, between 0 and 360) Select Case maxValue Case red If green >= blue Then If delta = 0 Then h = 0 Else h = 60 * (green - blue) / delta End If ElseIf green < blue Then h = 60 * (green - blue) / delta + 360 End If Case green h = 60 * (blue - red) / delta + 120 Case blue h = 60 * (red - green) / delta + 240 End Select ''# Calculate the saturation (between 0 and 1) If maxValue = 0 Then s = 0 Else s = 1D - (minValue / maxValue) End If ''# Scale the saturation and value to a percentage between 0 and 100 s *= 100 v *= 100 ''# Return a color in the new color space Return New HSV(CInt(Math.Round(h, MidpointRounding.AwayFromZero)), _ CInt(Math.Round(s, MidpointRounding.AwayFromZero)), _ CInt(Math.Round(v, MidpointRounding.AwayFromZero))) End Function
您没有发布用于从HSB（我称之为HSV）颜色转换为RGB的代码，但这是我使用的代码，再次使用介于0和1之间的临时值：
Public Function HSVtoRGB(ByVal H As Integer, ByVal S As Integer, ByVal V As Integer) As RGB ''# Scale the Saturation and Value components to be between 0 and 1 Dim hue As Decimal = H Dim sat As Decimal = S / 100D Dim val As Decimal = V / 100D Dim r As Decimal Dim g As Decimal Dim b As Decimal If sat = 0 Then ''# If the saturation is 0, then all colors are the same. ''# (This is some flavor of gray.) r = val g = val b = val Else ''# Calculate the appropriate sector of a 6-part color wheel Dim sectorPos As Decimal = hue / 60D Dim sectorNumber As Integer = CInt(Math.Floor(sectorPos)) ''# Get the fractional part of the sector ''# (that is, how many degrees into the sector you are) Dim fractionalSector As Decimal = sectorPos - sectorNumber ''# Calculate values for the three axes of the color Dim p As Decimal = val * (1 - sat) Dim q As Decimal = val * (1 - (sat * fractionalSector)) Dim t As Decimal = val * (1 - (sat * (1 - fractionalSector))) ''# Assign the fractional colors to red, green, and blue ''# components based on the sector the angle is in Select Case sectorNumber Case 0, 6 r = val g = t b = p Case 1 r = q g = val b = p Case 2 r = p g = val b = t Case 3 r = p g = q b = val Case 4 r = t g = p b = val Case 5 r = val g = p b = q End Select End If ''# Scale the red, green, and blue values to be between 0 and 255 r *= 255 g *= 255 b *= 255 ''# Return a color in the new color space Return New RGB(CInt(Math.Round(r, MidpointRounding.AwayFromZero)), _ CInt(Math.Round(g, MidpointRounding.AwayFromZero)), _ CInt(Math.Round(b, MidpointRounding.AwayFromZero))) End Function
编辑：此代码与Richard J. Ross III在C中提供的代码非常相似。 我在网上找到了尽可能多的不同算法，重写了大量代码，从每个代码中借用了最好的代码，并进行了大量测试以validation结果的准确性。 我忽略了我从谁借来的代码，因为这只是一个私人图书馆。 也许VB版本会帮助那些不希望从C转换的人。:-)
这是我的版本如何做到这一点（在C中，对不起，但不应该很难转换，只需用out或ref int替换int *和double * ，不要使用指针语法）
void colorlib_hsbtorgb(double hue, double saturation, double brightness, int *red, int *green, int *blue) { if (saturation == 0) { *red = *green = *blue = brightness; } else { // the color wheel consists of 6 sectors. Figure out which sector you're in. double sectorPos = hue / 60.0; int sectorNumber = (int)(floor(sectorPos)); // get the fractional part of the sector double fractionalSector = sectorPos - sectorNumber; // calculate values for the three axes of the color. double p = brightness * (1.0 - saturation); double q = brightness * (1.0 - (saturation * fractionalSector)); double t = brightness * (1.0 - (saturation * (1 - fractionalSector))); // assign the fractional colors to r, g, and b based on the sector the angle is in. switch (sectorNumber) { case 0: *red = brightness; *green = t; *blue = p; break; case 1: *red = q; *green = brightness; *blue = p; break; case 2: *red = p; *green = brightness; *blue = t; break; case 3: *red = p; *green = q; *blue = brightness; break; case 4: *red = t; *green = p; *blue = brightness; break; case 5: *red = brightness; *green = p; *blue = q; break; } } }
RGB到hsb：
void colorlib_rgbtohsb(int red, int green, int blue, double *hue, double *saturation, double *brightness) { double dRed = red / 255; double dGreen = green / 255; double dBlue = blue / 255; double max = fmax(dRed, fmax(dGreen, dBlue)); double min = fmin(dRed, fmin(dGreen, dBlue)); double h = 0; if (max == dRed && dGreen >= dBlue) { h = 60 * (dGreen - dBlue) / (max - min); } else if (max == dRed && dGreen < dBlue) { h = 60 * (dGreen - dBlue) / (max - min) + 360; } else if (max == dGreen) { h = 60 * (dBlue - dRed) / (max - min) + 120; } else if (max == dBlue) { h = 60 * (dRed - dGreen) / (max - min) + 240; } double s = (max == 0) ? 0.0 : (1.0 - (min / max)); *hue = h; *saturation = s; *brightness = max; }
如果我在C＃中找到我的代码，我将编辑这个答案....
那么使用Color GetBrightness，GetHue和GetSaturation方法呢？
如果您使用.net，为什么要重新发明轮子？
Dim c = Color.FromArgb(myRed, myGreen, myBlue) Dim h = c.GetHue() Dim s = c.GetSaturation() Dim b = c.GetBrightness()
使用Color结构，从RGB到HSB的转换应该相当容易：
Function RGBToHSB(rgb As RGBColor) As HSBColor Dim c As Color = Color.FromArgb(rgb.Red, rgb.Green, rgb.Blue) RGBToHSB.Hue = c.GetHue() RGBToHSB.Saturation = c.GetSaturation() RGBToHSB.Brightness = c.GetBrightness() End Function
但是，它不支持相反的情况。
解
您可以非常简单地计算亮度分量，因为它是R，G和B的最大值（参考： 罗彻斯特理工学院的RGB到HSV的公式）。 您可以通过除以255并乘以比例来缩放它。 这与现有代码中的操作相同：
maxRGB = Max(Max(rgb.Red, rgb.Green), rgb.Blue) b = maxRGB ... RGBToHSB.Brightness = b * 100 / 255
因此，最后您可以使用内置的.Netfunction，只计算亮度。 完整代码（不包括您的类型）：
Function RGBToHSB(rgb As RGBColor) As HSBColor Dim maxRGB As Double maxRGB = Max(Max(rgb.Red, rgb.Green), rgb.Blue) Dim c As Color = Color.FromArgb(rgb.Red, rgb.Green, rgb.Blue) RGBToHSB.Hue = c.GetHue() RGBToHSB.Saturation = c.GetSaturation() * 100 RGBToHSB.Brightness = maxRGB * 100 / 255 End Function
关于HSB（与HSV相同）
来自Darel Rex Finley ：
在HSV（也称为HSB）系统中，颜色的亮度是其V分量。 该组件被简单地定义为颜色的三个RGB分量中的任何一个的最大值 – 在确定V时忽略另外两个RGB分量。
根据Microsoft的Color.GetBrightness 文档 ：
获取此Color结构的色调饱和度 – 亮度（ HSB ）亮度值。
我发现一些引用说MSDN使用HSB，这意味着HSL就像来自MSDN博客的 HSL（参见评论）。 快速测试certificate这是真的（在C＃中）：
// Define a color which gives different HSL and HSB value Color c = Color.FromArgb(255, 0, 0); // Get the brightness, scale it from 0.0 - 1.0 up to 0 - 255 int bright = (int)(c.GetBrightness() * 255.00); // Output it Console.WriteLine(bright.ToString());
这导致值127 ，这显然是HSL。 如果是HSB，则该值应为RG和B的最大值（即255 ）。