在 RGB 和 HSB 颜色值之间切换的算法 [英] Algorithm to Switch Between RGB and HSB Color Values
问题描述
我阅读了文章在 RGB 和 HSB 颜色值之间切换的算法
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 < 0 Then h = h + 360
RGBToHSB.Hue = h
RGBToHSB.Saturation = s * 100 / 255
RGBToHSB.Brightness = b * 100 / 255
End Function
Function HSBToRGB(hsb As HSBColor) As RGBColor
Dim maxRGB, Delta As Double
Dim h, s, b As Double
h = hsb.Hue / 60
s = hsb.Saturation * 255 / 100
b = hsb.Brightness * 255 / 100
maxRGB = b
If s = 0 Then
HSBToRGB.Red = 0
HSBToRGB.Green = 0
HSBToRGB.Blue = 0
Else
Delta = s * maxRGB / 255
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
然后有人发帖说有错误但没有详细说明
Then there was someone who posted that there was a mistake but didn't elaborate much
但我认为h大于5时需要管理，例如颜色R:130 G:65 B:111
But I think it need to manage when h is more than 5, for example for the color 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)
Do I need to add in that piece of code? And I presume it should go into HSB to RGB (in my C# conversion)
...
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)
{
...
还有，应该像上面那样，还是
also, should it be like above, or
if (h > 6) { }
else if (h > 3) { }
推荐答案
使用内置于 .NET 的 Color 对象中的方法是不切实际的，因为正如一些答案指出的那样，它们不支持反向(转换HSB 颜色到 RGB).此外，Color.GetBrightness 实际上返回的是 lightness，而不是亮度/值.由于 HSB/HSV 和 HSL 颜色空间的相似性，它们之间的差异存在很多混淆(维基百科).我看到很多颜色选择器最终使用了错误的算法和/或模型.
Using the methods built into .NET's Color object is a non-starter because, as several of the answers point out, they don't support the reverse (converting an HSB color to RGB). Additionally, Color.GetBrightness actually returns lightness, rather than brightness/value. There is a lot of confusion over the differences between the HSB/HSV and HSL color spaces because of their similarities (Wikipedia). I see lots of color pickers that end up using the wrong algorithm and/or model.
在我看来，原始代码在计算色调值时遗漏了一些可能的情况，给定 RGB 颜色.我有点难以理解您正在考虑添加到代码中的内容，但是让我想到的第一件事(并且您似乎没有建议更正)是，当饱和度 = 0 时，您设置色调为-1.当您稍后将色调乘以 60 时，最终得到 -60，然后将其与 360 相加(If h <0 Then h = h + 360)，结果为 300，即不正确.
The original code looks to me like it misses a few possible scenarios when it calculates the value for hue, given an RGB color. It's a little difficult for me to follow the additions that you're contemplating to the code, but the first thing that jumps out at me (and that you don't appear to suggest correcting) is that when the saturation = 0, you set hue to -1. When you later multiply the hue by 60, you end up with -60, then you add that to 360 (If h < 0 Then h = h + 360), producing a result of 300, which is not correct.
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.结果已经过广泛的测试，结果几乎与 Photoshop 的颜色选择器给出的结果相同(除了它对颜色配置文件所做的补偿).发布的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)是我更喜欢将 RGB 值标准化为 0 到 1 之间来进行计算，而不是使用 0 到 255 之间的原始值. 这也消除了您发布的原始代码中的一些低效和多次转换的问题.
I use the following code (in VB.NET) to convert between RGB and HSB (which I call HSV). The results have been tested very extensively, and the results are virtually identical to those given by Photoshop's color picker (aside from the compensation it does for color profiles). The major difference between the posted code and mine (aside from the important portion that calculates the hue) is that I prefer normalizing the RGB values to be between 0 and 1 to do the calculations, rather than working with the original values between 0 and 255. This eliminates some of the inefficiencies and multiple conversions in the original code that you posted, as well.
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，再次使用介于 0 和 1 之间的中间值:
You didn't post the code you use to convert from an HSB (which I call HSV) color to RGB, but here's what I use, again working with interim values that are between 0 and 1:
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
此代码看起来与 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，重新编写了大量代码，借鉴了每个算法的优点，并进行了大量测试以验证结果的准确性.我忽略了我从谁那里借来的代码，因为这只是一个私人图书馆.也许 VB 版本会帮助那些不想从 C 进行转换的人.:-)
This code looks very similar to that provided in C by Richard J. Ross III. I hunted down as many different algorithms as I could find online, rewrote a lot of code borrowing the best from each of them, and did extensive testing to verify the accuracy of the results. I neglected to note who I borrowed code from, as this was just for a private library. Maybe the VB version will help someone who doesn't want to do a conversion from C. :-)
这篇关于在 RGB 和 HSB 颜色值之间切换的算法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
