Parent Topic: <A href="http://www.pcigeomatics.com/cgi-bin/pcihlp/IHS|ALGORITHM">ALGORITHM</a><hr>
<H4>HEXCONE</H4>
The following algorithm is used to convert RGB to IHS values using
the single-hexcone colour model.
<P>
<PRE>
 R = Red, G = Green, B = Blue
 I = Intensity, H = Hue, S = Saturation

 Max = Maximum(R,G,B)
 Min = Minimum(R,G,B)
 Delta = Max - Min

 I = Max

 If (Max &lt;&gt; 0) S = Delta / Max
 If (Max = 0)  S = 0

 If (S = 0) H = 0                       (Hue is undefined)

 If (R = Max) H = (G - B) / Delta       (between yellow and magenta)
 If (G = Max) H = 2 + (B - R) / Delta   (between cyan and yellow)
 If (B = Max) H = 4 + (R - G) / Delta   (between magenta and cyan)
 H = H * 60                             (convert Hue to degrees)
 If (H &lt; 0) H = H + 360                 (Hue must be positive)
 If (H &gt;= 360) H = H - 360              (Hue must be less than 360)
</PRE>
If output channels are all 8-bit, then Hue and Saturation values are
scaled between 0 and 255:
<P>
<PRE>
 H = H * (255 / 360)
 S = S * 255
</PRE>
The above algorithm was obtained from page 592 of the following text
book:
<P>
<PRE>
 Foley, J.D., A. van Dam, S.K. Feiner and J.F. Hughes, 1990.
 Computer Graphics: Principles and Practice (second edition).
 Addison-Wesley Publishing Company.
</PRE>
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Parent Topic: <A href="http://www.pcigeomatics.com/cgi-bin/pcihlp/IHS|ALGORITHM">ALGORITHM</a><br>
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