Color Space Transform
This sample source code illustrates the use of the
transformation between different image color spaces. The
sample code is based on Microsoft Visual Basic. The
Ilixis Developer's Corner does not warrant that the
sample source code. This sample source code is for
guidance and illustration purposes only.
' HSL values used are between 0 and 1
' RGB values used are between 0 and 255
' All variables used are of data type DOUBLE
RGB to HSL
TmpR = ( R / 255 )
TmpG = ( G / 255 )
TmpB = ( B / 255 )
' fnMin gives the minimum of the 3 parameters.
' In this case, its the minimum RGB value
TmpMin = fnMin( TmpR, TmpG, TmpB )
' fnMin gives the maximum of the 3 parameters.
' In this case, its the maximum RGB value
TmpMax = fnMax( TmpR, TmpG, TmpB )
' DelMax will be the delta between the Maximum and Minimum values
DelMax = TmpMax - TmpMin
L = ( TmpMax + TmpMin ) / 2
If ( DelMax == 0 ) Then
' This is a gray
H = 0
S = 0
Else
If ( L < 0.5 ) Then
S = DelMax / ( TmpMax + TmpMin )
Else
S = DelMax / ( 2 - DelMax )
End If
DelR = ( ( ( TmpMax - TmpR ) / 6 ) + ( DelMax / 2 ) ) / DelMax
DelG = ( ( ( TmpMax - TmpG ) / 6 ) + ( DelMax / 2 ) ) / DelMax
DelB = ( ( ( TmpMax - TmpB ) / 6 ) + ( DelMax / 2 ) ) / DelMax
If ( TmpR == TmpMax ) Then
H = DelB - DelG
ElseIf ( TmpG == TmpMax ) Then
H = ( 1 / 3 ) + DelR - DelB
ElseIf ( TmpB == TmpMax ) Then
H = ( 2 / 3 ) + DelG - DelR
End If
If ( H < 0 ) Then
H = H + 1
End If
If ( H > 1 ) Then
H = H - 1
End If
End If
HSL to RGB
If ( S = 0 ) Then
R = L * 255
G = L * 255
B = L * 255
Else
If ( L < 0.5 ) Then
Tmp2 = L * ( 1 + S )
Else
Tmp2 = ( L + S ) - ( S * L )
End If
Tmp1 = 2 * L - Tmp2
R = 255 * fnHtoRGB( Tmp1, Tmp2, H + ( 1 / 3 ) )
G = 255 * fnHtoRGB( Tmp1, Tmp2, H )
B = 255 * fnHtoRGB( Tmp1, Tmp2, H - ( 1 / 3 ) )
End If
Private Function fnHtoRGB( v1, v2, v3 )
If ( v3 < 0 ) Then
v3 = v3 + 1
End If
If ( v3 > 1 ) Then
v3 = v3 - 1
End If
If ( ( 6 * v3 ) < 1 ) Then
fnHtoRGB = ( v1 + ( v2 - v1 ) * 6 * v3 )
ElseIf ( ( 2 * v3 ) < 1 ) Then
fnHtoRGB = v2
ElseIf ( ( 3 * v3 ) < 2 ) Then
fnHtoRGB = ( v1 + ( v2 - v1 ) * ( ( 2 / 3 ) - v3 ) * 6 )
Else
fnHtoRGB = v1
End If
End Function
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