BB bugged or just the command ?

the following code check all the tiles in one picture and make a new tileset with the uniques tiles only

hope you like

Graphics 800,600,32,02
Global mytileset=CreateImage(640,480,1,2); or loadimage the tileset
;------------------------------------------
; this part create a 'tileset' remove it if you load one
SetBuffer ImageBuffer(mytileset)
For blah=1 To 150
	Color 255,2552,55
	Text Rand(640),Rand(480),"O"
Next
;-------------------------------------------
SetBuffer FrontBuffer()
comp$=comparetileset(mytileset,32,32)
maxtile_x=ImageWidth(mytileset)/32
maxtile_y=ImageHeight(mytileset)/32
maxtiles=maxtile_x*maxtile_y-1
Text 0,10,"found "+Len(comp$)/4+"of"+maxtiles+" tiles matching ("+(maxtiles-Len(comp$)/4)+")unique tiles)
Text 0,20,"press a key to compute new tileset"
Flip
WaitKey
newtileset=compute(mytileset,32,32,comp$)
Flip
WaitKey
End
Function comparetileset$(image,width,height)
DrawBlock mytileset,0,0
Flip
maxtile_x=ImageWidth(image)/width
maxtile_y=ImageHeight(image)/height
maxtiles=maxtile_x*maxtile_y-1
For tile=0 To maxtiles
	find=False
	For a=1 To Len(comp$)/4
		If tile=unformat(comp$,a)
			find=True
		EndIf
	Next
	If find=False
	yt=Int(tile/maxtile_x)	
	xt=tile-(yt*maxtile_x)

	LockBuffer BackBuffer() ;ImageBuffer(image)
	For tile2=0 To maxtiles
		If tile2>=tile
		find=False
		For a=1 To Len(comp$)/4
			If tile2=unformat(comp$,a)
				find=True
			EndIf
		Next
		If find=False
		yt2=Int(tile2/maxtile_x)	
		xt2=tile2-(yt2*maxtile_x)
		xc=0
		yc=0
		If tile<>tile2
		Repeat			
			c1=ReadPixelFast(xt*width+xc,yt*height+yc,BackBuffer());,ImageBuffer(image))
			c2=ReadPixelFast(xt2*width+xc,yt2*height+yc,BackBuffer());,ImageBuffer(image))
			xc=xc+1
			If xc>width-1
				xc=0
				yc=yc+1
			EndIf
		Until c1<>c2 Or yc>height-1
		If yc>height-1
			comp$=comp$+format$(tile2)
		EndIf
		EndIf
		EndIf
		EndIf
	Next
	UnlockBuffer BackBuffer() ;ImageBuffer(image)
	EndIf

Next 
Return comp$
End Function
Function format$(value) 
	Return String$("0",4-Len(Str(value)))+Str(value)
End Function
Function unformat(strin$,pos)
	Return Mid(strin$,((pos-1)*4)+1,4)
End Function
Function compute(image,width,height,comp$)
	maxtile_x=ImageWidth(image)/width
	maxtile_y=ImageHeight(image)/height
	temp=CreateImage(ImageWidth(image),ImageHeight(image),1,2)
	maxtiles=(maxtile_x*maxtile_y)-1
	Newpos=0
	Color 255,255,255
	Rect 0,0,800,600,1
	For tile=0 To maxtiles
		matching=False
		For search=1 To Len(comp$)/4
			If tile=unformat(comp$,search)
				matching=True
			EndIf
		Next 
		If matching=False
			yt=Int(tile/maxtile_x)	
			xt=tile-(yt*maxtile_x)
			yt2=Int(Newpos/maxtile_x)	
			xt2=Newpos-(yt2*maxtile_x)
			CopyRect xt*width,yt*height,width,height,xt2*width,yt2*height,ImageBuffer(image),BackBuffer();ImageBuffer(temp)
			newpos=newpos+1
		EndIf
	Next
End Function