Code archives/Graphics/Simple Contour
This code has been declared by its author to be Public Domain code.
Download source code
| |||||
| Relies on the mean RGB values of surrounding pixels to determine if a contour is to be drawn. Has a tolerance parameter which determines baseline ratio for difference of mean RGB values. Suprisingly fast, but possibly not ideal for realtime application. | |||||
Global Path$=GetEnv("PROGRAMFILES")+"\Blitz3D\samples\birdie\thunder\hmap.bmp"
Graphics 800,600,32,6
SetBuffer BackBuffer()
Image=LoadImage(Path$)
ccc=ContourMap(Image)
While Not KeyDown(1)
If KeyDown(57) And (MilliSecs()-lastkey>250)
FlushKeys
lastkey=MilliSecs()
display=Not(display)
End If
Cls
DrawImage (ccc*display)+(Image*(1-display)),0,0
Color 0,255,0
Text 0,0,"Press Space to switch image / contour map"
Flip
Wend
Function ContourMap%(Image%,Tolerance#=0.5)
If (Not(Image)) Then Return 0
Local Contour%=CreateImage(ImageWidth(Image),ImageHeight(Image))
Local X1=0
Local Y1=0
Local X2=ImageWidth(Image)-1
Local Y2=ImageHeight(Image)-1
Buffer=(ImageBuffer(Image))
CBuffer=(ImageBuffer(Contour))
LockBuffer Buffer
LockBuffer CBuffer
For x=X1 To X2
For y=Y1 To Y2
Pixel=ReadPixelFast(x,y,Buffer)
If (AdjacentDifference(Pixel,x,y,Image,Tolerance#)) Then WritePixelFast x,y,RGBa(255,255,255),CBuffer
Next
Next
UnlockBuffer ImageBuffer(Image)
UnlockBuffer ImageBuffer(Contour)
Return Contour
End Function
Function PixelTopLeft%(Image%,x%,y%)
If (Not(Image)) Then Return -1
Local X1=1
Local Y1=1
Local X2=ImageWidth(Image)-2
Local Y2=ImageHeight(Image)-2
If (Not(x>=X1 And y>=Y1)) Then Return -1
x=x-1
y=y-1
Local Buffer%=ImageBuffer(Image)
;LockBuffer Buffer
Local nReturn%=ReadPixelFast(x,y,Buffer)
;UnlockBuffer Buffer
Return nReturn
End Function
Function PixelTopMid%(Image,x,y)
If (Not(Image)) Then Return -1
Local X1=1
Local Y1=1
Local X2=ImageWidth(Image)-2
Local Y2=ImageHeight(Image)-2
If (Not(y>=Y1)) Then Return -1
y=y-1
Local Buffer%=ImageBuffer(Image)
;LockBuffer Buffer
Local nReturn%=ReadPixelFast(x,y,Buffer)
;UnlockBuffer Buffer
Return nReturn
End Function
Function PixelTopRight%(Image,x,y)
If (Not(Image)) Then Return -1
Local X1=1
Local Y1=1
Local X2=ImageWidth(Image)-2
Local Y2=ImageHeight(Image)-2
If (Not(x<=X2 And y>=Y1)) Then Return -1
x=x+1
y=y-1
Local Buffer%=ImageBuffer(Image)
;LockBuffer Buffer
Local nReturn%=ReadPixelFast(x,y,Buffer)
;UnlockBuffer Buffer
Return nReturn
End Function
Function PixelMidLeft%(Image,x,y)
If (Not(Image)) Then Return -1
Local X1=1
Local Y1=1
Local X2=ImageWidth(Image)-2
Local Y2=ImageHeight(Image)-2
If (Not(x>=X1)) Then Return -1
x=x-1
Local Buffer%=ImageBuffer(Image)
;LockBuffer Buffer
Local nReturn%=ReadPixelFast(x,y,Buffer)
;UnlockBuffer Buffer
Return nReturn
End Function
Function PixelMidRight%(Image,x,y)
If (Not(Image)) Then Return -1
Local X1=1
Local Y1=1
Local X2=ImageWidth(Image)-2
Local Y2=ImageHeight(Image)-2
If (Not(x<=X2)) Then Return -1
x=x+1
Local Buffer%=ImageBuffer(Image)
;LockBuffer Buffer
Local nReturn%=ReadPixelFast(x,y,Buffer)
;UnlockBuffer Buffer
Return nReturn
End Function
Function PixelBotLeft%(Image,x,y)
If (Not(Image)) Then Return -1
Local X1=1
Local Y1=1
Local X2=ImageWidth(Image)-2
Local Y2=ImageHeight(Image)-2
If (Not(x>=X1 And y<=Y2)) Then Return -1
x=x-1
y=y+1
Local Buffer%=ImageBuffer(Image)
;LockBuffer Buffer
Local nReturn%=ReadPixelFast(x,y,Buffer)
;UnlockBuffer Buffer
Return nReturn
End Function
Function PixelBotMid%(Image,x,y)
If (Not(Image)) Then Return -1
Local X1=1
Local Y1=1
Local X2=ImageWidth(Image)-2
Local Y2=ImageHeight(Image)-2
If (Not(y<=Y2)) Then Return -1
y=y+1
Local Buffer%=ImageBuffer(Image)
;LockBuffer Buffer
Local nReturn%=ReadPixelFast(x,y,Buffer)
;UnlockBuffer Buffer
Return nReturn
End Function
Function PixelBotRight%(Image,x,y)
If (Not(Image)) Then Return -1
Local X1=1
Local Y1=1
Local X2=ImageWidth(Image)-2
Local Y2=ImageHeight(Image)-2
If (Not(x<=X2 And y<=Y2)) Then Return -1
x=x+1
y=y+1
Local Buffer%=ImageBuffer(Image)
;LockBuffer Buffer
Local nReturn%=ReadPixelFast(x,y,Buffer)
;UnlockBuffer Buffer
Return nReturn
End Function
Function AdjacentDifference%(Test_aRGB%,x%,y%,Image%,Tolerance#)
Local Mean_aRGB%=DeSaturatePixel(Test_aRGB%)
Local Valid%=False
Local Adjacent%
Adjacent%=DeSaturatePixel(PixelTopLeft(Image,x,y))
Valid=(Float(Float(Red(Test_aRGB))/Float(Red(Adjacent)))<Tolerance#)
If (Adjacent=-1) Then Valid=False
If (Valid) Return True
Adjacent%=DeSaturatePixel%(PixelTopMid(Image,x,y))
Valid=(Float(Float(Red(Test_aRGB))/Float(Red(Adjacent)))<Tolerance#)
If (Adjacent=-1) Then Valid=False
If (Valid) Return True
Adjacent%=DeSaturatePixel%(PixelTopRight(Image,x,y))
Valid=(Float(Float(Red(Test_aRGB))/Float(Red(Adjacent)))<Tolerance#)
If (Adjacent=-1) Then Valid=False
If (Valid) Return True
Adjacent%=DeSaturatePixel%(PixelMidLeft(Image,x,y))
Valid=(Float(Float(Red(Test_aRGB))/Float(Red(Adjacent)))<Tolerance#)
If (Adjacent=-1) Then Valid=False
If (Valid) Return True
Adjacent%=DeSaturatePixel%(PixelMidRight(Image,x,y))
Valid=(Float(Float(Red(Test_aRGB))/Float(Red(Adjacent)))<Tolerance#)
If (Adjacent=-1) Then Valid=False
If (Valid) Return True
Adjacent%=DeSaturatePixel%(PixelBotLeft(Image,x,y))
Valid=(Float(Float(Red(Test_aRGB))/Float(Red(Adjacent)))<Tolerance#)
If (Adjacent=-1) Then Valid=False
If (Valid) Return True
Adjacent%=DeSaturatePixel%(PixelBotMid(Image,x,y))
Valid=(Float(Float(Red(Test_aRGB))/Float(Red(Adjacent)))<Tolerance#)
If (Adjacent=-1) Then Valid=False
If (Valid) Return True
Adjacent%=DeSaturatePixel%(PixelBotRight(Image,x,y))
Valid=(Float(Float(Red(Test_aRGB))/Float(Red(Adjacent)))<Tolerance#)
If (Adjacent=-1) Then Valid=False
Return Valid
End Function
Function RGBa%(R%,G%,B%,a%=0)
; Returns aRGB Value from components.
Return ((a% Shl 24) Or (R% Shl 16) Or (G% Shl 8) Or B%)
End Function
;_______________________________________________________________________________________________________________________
;_______________________________________________________________________________________________________________________
Function Red(RGBa_Value%)
; Returns Red component.
Return (RGBa_Value% Shr 16 And 255)
End Function
;_______________________________________________________________________________________________________________________
;_______________________________________________________________________________________________________________________
Function Green(RGBa_Value%)
; Returns Green component.
Return (RGBa_Value% Shr 8 And 255)
End Function
;_______________________________________________________________________________________________________________________
;_______________________________________________________________________________________________________________________
Function Blue(RGBa_Value%)
; Returns Blue component.
Return (RGBa_Value% And 255)
End Function
;_______________________________________________________________________________________________________________________
;_______________________________________________________________________________________________________________________
Function Alpha%(RGBa_Value%)
; Returns Alpha component.
Return (RGBa_Value% Shr 24 And 255)
End Function
;_______________________________________________________________________________________________________________________
;_______________________________________________________________________________________________________________________
Function DeSaturatePixel(Colour%)
; Returns the DeSaturated (Mean intensity) RGBa value of a particular pixel
a%=Alpha%(Colour%)
R%=Red%(Colour%)
G%=Green%(Colour%)
B%=Blue%(Colour%)
Colour%=((R%-(R%*0.333)*0.5)+(G%-(G%*0.333)*0.5)+(B%-(B%*0.333)*0.5))
Return RGBa%(Colour%,Colour%,Colour%,a%)
End Function |
Comments
| ||
| Deprecated. Now obsolete due to the ContourImage function here: http://blitzbasic.com/codearcs/codearcs.php?code=2847 |
Code Archives Forum
   |