Hi everyone!
This program will nicely dither your images, for mobile apps. Enjoy!
It works in the free demo version of pure basic, a nice IDE though not suited for mobile devices.
Please read and season to taste.
; Dither to RGB565 by Artist F.P.Brixey
;Please note: source file must be 32bit PNG with alpha.
;No alpha chanel produces a black image.
;If so, please process your source image:
;GIMP->Layer->transparency->add alpha chanel
InitSprite() : InitKeyboard()
Procedure.c rand_()
;write here your favorite hand-crafted chaos generator
a.c= Random(1)
a= Random(787) ; (let's shuffle!)
a=(Random(9955) & $00ff)
ProcedureReturn a ; type is char, unsigned byte please.
EndProcedure
Procedure.c from8to6(n.c) ; c is char, unsigned byte.
; We want to chop and dither the 2 LSB
;ProcedureReturn (n & $00fc) ; for special effects?
n2.c= n & ($00ff-$0003)
If n2 <$00fc And n & $0003 > rand_() & $0003
n2=n2+$0004
EndIf
ProcedureReturn n2
EndProcedure
Procedure.c from8to5(n.c)
; We want to chop and dither the 3 LSB
; You get the traditional careless banding by adding here:
;ProcedureReturn (n & $00f8) ; for special effects?
n2.c= n & ($00ff-$0007)
If n2 <$00f8 And n & $0007 > rand_() & $0007
n2=n2+$0008
EndIf
ProcedureReturn n2
EndProcedure
Procedure show(ima)
scrnum=OpenScreen(1024,768,32,"")
StartDrawing(ScreenOutput())
DrawAlphaImage(ImageID(ima),0,0)
;Box(20,20,40,20,RGB(122,122,255))
StopDrawing()
FlipBuffers()
Repeat
Delay(80) : ExamineKeyboard()
Until KeyboardPushed(#PB_Key_Escape)
CloseScreen() ; was a quick check
EndProcedure
sourcename$=OpenFileRequester("Open a source image (PNG format)","","*.*", 0)
UsePNGImageDecoder()
imnum_src=LoadImage(#PB_Any,sourcename$)
; BMP is default (leave the last argument empty). for other formats, use
;UseJPEGImageDecoder() UseJPEG2000ImageDecoder() UsePNGImageDecoder()
;UseTIFFImageDecoder() UseTGAImageDecoder()
imW=ImageWidth(imnum_src)
imH=ImageHeight(imnum_src)
If imnum_src =0 : MessageRequester ("Problem","Image is not loaded.") : End
EndIf
;show(imnum_src) ; Press escape
imnum_target = CreateImage(#PB_Any,imW,imH,32)
For j=0 To imH-1
For i=0 To imW-1
StartDrawing(ImageOutput(imnum_src))
DrawingMode(#PB_2DDrawing_AllChannels)
Rp=Red(Point(i,j))
Gp=Green(Point(i,j))
Bp=Blue(Point(i,j))
Ap=Alpha(Point(i,j))
; alpha remains unchanged. Up to you.
StopDrawing()
rr=from8to5(Rp)
gg=from8to6(Gp)
bb=from8to5(Bp)
StartDrawing(ImageOutput(imnum_target))
DrawingMode(#PB_2DDrawing_AllChannels)
Plot(i,j,RGBA(rr,gg,bb,Ap)) ; with undithered alpha.
StopDrawing()
Next
Next
target$=sourcename$+"_dith565.png" ; change it freely.
; possibly: saveimagerequester(...
UsePNGImageEncoder()
s_i=SaveImage(imnum_target,target$, #PB_ImagePlugin_PNG,0,32) ;
;file format is still 32 bits RGBA.
If s_i <>0
i=MessageRequester("Right", "Image was saved o.k.",#PB_MessageRequester_Ok )
Else
i=MessageRequester("Sorry", "Image is not saved.",#PB_MessageRequester_Ok )
End
EndIf
;show(imnum_target) ;now check the result. Reclaim your freedom by pressing 'escape'.
End
Oh well, I haven´t tried, but a little while tried dither fade things...similar to Card Clash SNKvsCAP.
This is the patterns I made, I hope it has anything to do with the post and helps. :-[