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POAlgorithm to Switch Between RGB and HSB Color Values
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  1. POAlgorithm to Switch Between RGB and HSB Color Values
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    copied!<p>I read the article <a href="http://www.devx.com/tips/Tip/41581" rel="noreferrer">Algorithm to Switch Between RGB and HSB Color Values</a></p> <pre><code>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 &lt;&gt; 0) Then s = 255 * Delta / maxRGB Else s = 0 End If If (s &lt;&gt; 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 &lt; 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 &gt; 3 Then HSBToRGB.Blue = CByte(Round(maxRGB)) If h &gt; 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 &gt; 1 Then HSBToRGB.Green = CByte(Round(maxRGB)) If h &gt; 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 &gt; -1 Then HSBToRGB.Red = CByte(Round(maxRGB)) If h &gt; 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 </code></pre> <p>Then there was someone who posted that there was a mistake but didn't elaborate much</p> <blockquote> <p>But I think it need to manage when h is more than 5, for example for the color R:130 G:65 B:111</p> </blockquote> <pre><code>If h &gt; 5 Then HSBToRGB.Red = CByte(Round(maxRGB)) If h &gt; 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 </code></pre> <p>Do I need to add in that piece of code? And I presume it should go into HSB to RGB (in my C# conversion)</p> <pre><code>... if (s != 0) { delta = s * maxRGB / 255; if (h &gt; 5) rgb.Red = Convert.ToByte(Math.Round(maxRGB)); if (h &gt; 6) { rgb.Green = Convert.ToByte(Math.Round(maxRGB - delta)); rgb.Blue = Convert.ToByte(rgb.Green - Math.Round((h - 6) * delta)); } if (h &gt; 3) { ... </code></pre> <p>also, should it be like above, or</p> <pre><code>if (h &gt; 6) { } else if (h &gt; 3) { } </code></pre>
 

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