Overflow

[DR00ME]

Public Shared Sub HLSToRGB(ByVal inputH As Short, ByVal inputS As Single, ByVal inputL As Single)

           Dim rR As Single = 0
           Dim rG As Single = 0
           Dim rB As Single = 0
           Dim Min As Single, Max As Single
           inputH = inputH / 60

           If inputS = 0 Then
               ' Achromatic case:
               rR = inputL
               rG = inputL
               rB = inputL
           Else
               ' Chromatic case:
               If inputL <= 0.5 Then
                   ' Get Min value:
                   Min = inputL * (1 - inputS)
               Else
                   ' Get Min value:
                   Min = inputL - inputS * (1 - inputL)
               End If
               ' Get the Max value:
               Max = 2 * inputL - Min

               ' Now depending on sector we can evaluate the h,l,s:
               If (inputH < 1) Then
                   rR = Max
                   If (inputH < 0) Then
                       rG = Min
                       rB = rG - inputH * (Max - Min)
                   Else
                       rB = Min
                       rG = inputH * (Max - Min) + rB
                   End If
               ElseIf (inputH < 3) Then
                   rG = Max
                   If (inputH < 2) Then
                       rB = Min
                       rR = rB - (inputH - 2) * (Max - Min)
                   Else
                       rR = Min
                       rB = (inputH - 2) * (Max - Min) + rR
                   End If
               Else
                   rB = Max
                   If (inputH < 4) Then
                       rR = Min
                       rG = rR - (inputH - 4) * (Max - Min)
                   Else
                       rG = Min
                       rR = (inputH - 4) * (Max - Min) + rG
                   End If

               End If

           End If
           AIvision.cR = rR * 255
           AIvision.cG = rG * 255
           AIvision.cB = rB * 255

 

 

all right... AIvision.cR = rR * 255 is overflowing because rR is getting over 1 when inputH is over around 340 (also depends on the other input values)... does anyone know why ? btw. this code is HSL to RGB converter... lol hope you are good at math.

 

AIvision class output values (RGB) cR, cG and rB are type of Byte. And after doing a bit more of researching I found out that cR got 288 and it should be between 0-255.

 

 

Anyway the overflowing happened e.g. with these input values:

346,8 ; 0,4464286 ; 0,4392157

Edited February 29, 2004 by DR00ME

[PlausiblyDamp]

Bytes can only contain a value between 0 and 255, anything bigger will result in an overflow.

[DR00ME]

Exactly... but it is overflowing because there is something dodgy in the code... after chaging the inputH / 60 to inputH / 68 it works even with inputH value of 358 (notice the max value of hue is 360).... but then again now I can't know if the HSL to RGB conversion is accurate...

[PlausiblyDamp]

Is there a reason why inputH, inputS and inputL are declared single? I was always under the impression that these are integer values.

[DR00ME]

Yes, if you get .hue .saturation and .brightness(luminance) from some pixel using vb.net... you get .hue as 0-360 (short in code)(sometimes talked as degrees because the colors are in a colorcircle) .saturation = 0.0000000-1.0000000 and same with brightness....I think there is some bug in the code.... but after checking one professional material (?) this is the 'official' conversion formula (not in proper vb.net format)

 

 

 if ( S == 0 )                       //HSL values = From 0 to 1
{
  R = L * 255                      //RGB results = From 0 to 255
  G = L * 255
  B = L * 255
}
else
{
  if ( L < 0.5 ) var_2 = L * ( 1 + S )
  else           var_2 = ( L + S ) - ( S * L )

  var_1 = 2 * L - var_2

  R = 255 * Hue_2_RGB( var_1, var_2, H + ( 1 / 3 ) ) 
  G = 255 * Hue_2_RGB( var_1, var_2, H )
  B = 255 * Hue_2_RGB( var_1, var_2, H - ( 1 / 3 ) )
} 


--------------------------------------------------------------------------------

Hue_2_RGB( v1, v2, vH )             //Function Hue_2_RGB
{
  if ( vH < 0 ) vH += 1
  if ( vH > 1 ) vH -= 1
  if ( ( 6 * vH ) < 1 ) return ( v1 + ( v2 - v1 ) * 6 * vH )
  if ( ( 2 * vH ) < 1 ) return ( v2 )
  if ( ( 3 * vH ) < 2 ) return ( v1 + ( v2 - v1 ) * ( ( 2 / 3 ) - vH ) * 6 )
  return ( v1 )
}

 

 

I would be really glad if someone converted it to vb.net format :) sure I'm able to to it but function 2 concerns me.. there are 4 return cases .. but I just wonder why there is return v1 in the end... like if one of the if cases are true it returns a value and then in the end it returns a value AGAIN ? eh... confusing...

 

or how does return function work in c++ or whatever that language is (or just pseudo?)... if it has returned a value does it exit the function ?

Edited February 29, 2004 by DR00ME

[DR00ME]

Now I made the conversion to vb.net... im getting wrong colors :)

 

[Vb] Public Shared Sub HLSToRGB(ByVal inputH As Short, ByVal inputS As Single, ByVal inputL As Single)

 

 

Dim rR As Single = 0

Dim rG As Single = 0

Dim rB As Single = 0

Dim Min As Single, Max As Single

 

 

If inputS = 0 Then

rR = inputL * 255

rG = inputL * 255

rB = inputL * 255

Else

If inputL < 0.5 Then

Min = inputL * (1 + inputS)

Else

Min = (inputL + inputS) - (inputS * inputL)

End If

 

Max = 2 * inputL - Min

 

rR = 255 * Hue_To_RGB(Max, Min, (inputH + (1 / 3)))

rG = 255 * Hue_To_RGB(Max, Min, inputH)

rB = 255 * Hue_To_RGB(Max, Min, (inputH - (1 / 3)))

 

End If

 

AIvision.cR = rR

AIvision.cG = rG

AIvision.cB = rB

End Sub

 

Private Shared Function Hue_To_RGB(ByVal inputMax As Single, ByVal inputMin As Single, ByVal inputHue As Single) As Single

 

If inputHue < 0 Then

inputHue += 1

End If

 

If (inputHue > 1) Then

inputHue -= 1

End If

 

If ((6 * inputHue) < 1) Then

Return (inputMax + (inputMin - inputMax) * 6 * inputHue)

End If

 

If ((2 * inputHue) < 1) Then

Return (inputMin)

End If

 

If ((3 * inputHue) < 2) Then

Return (inputMax + (inputMin - inputMax) * ((2 / 3) - inputHue) * 6)

End If

 

Return (inputMax)

 

End Function[/code]

Edited February 29, 2004 by DR00ME

[PlausiblyDamp]

A return statements exits the function and passes the value back to the calling routine in one statement.

 

you may fine these handy though link 1 and link 2

[DR00ME]

cheers, I'll check em out...

[DR00ME]

I red them both but nothing useful there....2nd was one kind of conversion which is non-standard = you cant use it to reverse the vb.net RGB to HSL because it is using integer values for HSL. damn I don't know what im doing wrong.... It is still showing wrong colors :(

 

this is what I got so far:

 

    Public Class HSL_To_RGB

       Public Shared Sub HLSToRGB(ByVal inputH As Short, ByVal inputS As Single, ByVal inputL As Single)


           Dim rR As Single = 0
           Dim rG As Single = 0
           Dim rB As Single = 0
           Dim Min As Single, Max As Single

           If inputL = 0 Then 'luminance = 0, means basically that brightness is 0.
               rR = 0
               rG = 0
               rB = 0
           Else
               If inputS = 0 Then 'When saturation is 0, color is undefined (gray,black,white)
                   rR = CByte(inputL * 255)
                   rG = CByte(inputL * 255)
                   rB = CByte(inputL * 255)
               Else
                   If inputL <= 0.5 Then
                       Min = inputL * (1 + inputS)
                   Else
                       Min = inputL + inputS - (inputS * inputL)
                   End If

                   Max = 2 * inputL - Min

                   rR = 255 * Hue_To_RGB(Max, Min, (inputH + (1 / 3)))
                   rG = 255 * Hue_To_RGB(Max, Min, inputH)
                   rB = 255 * Hue_To_RGB(Max, Min, (inputH - (1 / 3)))

               End If
           End If

           AIvision.cR = CByte(rR)
           AIvision.cG = CByte(rG)
           AIvision.cB = CByte(rB)

       End Sub

       Private Shared Function Hue_To_RGB(ByVal inputMax As Single, ByVal inputMin As Single, ByVal inputHue As Single) As Single

           If inputHue < 0 Then
               inputHue += 1
           End If

           If (inputHue > 1) Then
               inputHue -= 1
           End If

           If ((6 * inputHue) < 1) Then
               Return (inputMax + (inputMin - inputMax) * 6 * inputHue)
           End If

           If ((2 * inputHue) < 1) Then
               Return (inputMin)
           End If

           If ((3 * inputHue) < 2) Then
               Return (inputMax + (inputMin - inputMax) * ((2 / 3) - inputHue) * 6)
           End If

           Return (inputMax)

       End Function

Edited February 29, 2004 by DR00ME

[DR00ME]

Another version of it I made:

 

        Public Shared Sub HLSToRGB(ByVal inputH As Short, ByVal inputS As Single, ByVal inputL As Single)

           Dim rR As Single = 0
           Dim rG As Single = 0
           Dim rB As Single = 0
           Dim Min As Single, Max As Single
           inputH = inputH / 360.0

           If inputL = 0 Then
               rR = 0
               rG = 0
               rB = 0
           Else
               If inputS = 0 Then
                   rR = CByte(inputL * 255)
                   rG = CByte(inputL * 255)
                   rB = CByte(inputL * 255)
               Else
                   If inputL <= 0.5 Then
                       Min = inputL * (1.0 + inputS)
                   Else
                       Min = inputL + inputS - (inputS * inputL)
                   End If

                   Max = 2 * inputL - Min

                   Dim t3() As Single = {(inputH + 1.0 / 3.0), inputH, (inputH - 1.0 / 3.0)}
                   Dim clr() As Single = {0, 0, 0}
                   Dim i As Integer

                   For i = 0 To 2

                       If (t3(i) < 0) Then
                           t3(i) += 1.0
                       End If

                       If (t3(i) > 1) Then
                           t3(i) -= 1.0
                       End If

                       If ((6.0 * t3(i)) < 1.0) Then
                           clr(i) = Max + (Min - Max) * t3(i) * 6.0
                       ElseIf (2.0 * t3(i) < 1.0) Then
                           clr(i) = Min
                       ElseIf ((3.0 * t3(i)) < 2.0) Then
                           clr(i) = (Max + (Min - Max) * ((2.0 / 3.0) - t3(i)) * 6.0)
                       Else
                           clr(i) = Max
                       End If
                   Next i

                   rR = clr(0) * 255
                   rG = clr(1) * 255
                   rB = clr(2) * 255

               End If
           End If

           AIvision.cR = CByte(rR)
           AIvision.cG = CByte(rG)
           AIvision.cB = CByte(rB)

       End Sub

 

im getting gray colors... what in earth is wrong with it...

[DR00ME]

lol now I found a new kind of conversion method:

 

HSL to RGB : 

First of all normalise H in the range of 0-360. Here there are 3 cases to be considered. 

0<H<120 : 

r = i*{1+[(s*CosH)/Cos(60-H)]} 

b = i*(1 - s) 

g = 3i*{i-[(r+b)/3*i]} 

120<H<240 : 

g = i*{1+[(s*Cos(H-120))/Cos(180-H)]} 

r = i*(1 - s) 

b = 3i*{i-[(r+g)/3*i]} 

240<H<360 : 

b = i*{1+[(s*Cos(H-240))/Cos(300-H)]} 

g = i*(1 - s) 

r = 3i*{i-[(g+b)/3*i]}

[Iceplug]

In the second one, I noticed this line:

Dim t3() As Single = {(inputH + 1.0 / 3.0), inputH, (inputH - 1.0 / 3.0)}

I don't know if you are aware but division is handled before the addition, which means you are adding 0.3 to inputH, an Integer, and the 0.3 will be rounded to a 0 for integer addition. :)

Well, a short is a short integer, so it is still an Integer.

[DR00ME]

What would I do without you iceplug!!!!!!!!!!!!!!!!!!!!?!?!?!?

 

you just saved my day, now im able to go to sleep it is 3:15am and I got school at 7am lol... it got so stressing man, I mean ffs I searched google and clicked every HSL to RGB link ...just saw same old bull there...made 3-4 diff version of the code until now... YES the input value is short 0 - 360 but in the sub proggy it doesnt work as you stated! so I had to change the input type to single...and WOOOHOO no more overflowing or other problems... I was so frustrated I even tried the bloody ColoHSLtoRGB API function....

 

Public Declare Function ColorHLSToRGB Lib "SHLWAPI.DLL" (ByVal wHue As Integer, ByVal wLuminance As Integer, ByVal wSaturation As Integer) As Long

 

that bloody function is using HUE, SATURATION and LUMINANCE values of 0-240 ...and as you can see those are damn integers..... so if i get pixelvalues with vb.net .gethue .getsaturation .getbrightness i get values 0-360, 0.0000000 - 1.0000000, 0.0000000 - 1.0000000 now to insert them to that bloody function you have to multiply sat and brightness with 240..... and convert them to int... and after that you get bloody LONG value out of the Api-funciton.... and to get r ,g and b out of it you have to do this bloody operation:

 

dim blaa as long

 

blaa = ColorHLSToRGB(240,240,240)

 

nRed = blaa And 255

nGreen = (blaa / 256) And 255

nBlue = (blaa / 65536) And 255

 

hooray now you got inaccurate R,G,B values and they correspond hue sat bri of 0-240 0-240 0-240 and you cant compare them with vb.net .gethue .getsaturation getbrightness just because you had to convert the values to non-standard BS 0-240 which is btw used in bloody ms-paint! one other funny thing in vb.net is that you can e.g. lblColor.backcolor = Color.FromArgb(cR, cG, cB) but not from hue sat bri.

 

P.S. ICEPLUG rox! :D

Edited March 1, 2004 by DR00ME