converting colours... - BlitzCoder.net

-=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- (c) WidthPadding Industries 1987 0\|288\|0 -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=- -=+=-
Socoder -> Blitz -> converting colours...
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Wed, 10 Aug 2011, 06:43
spinal	Update! removed the forced palette entries added max_colours variable to set the number of colours you want added a fifth dither option, a simple pattern dither, looks terrible, but it's there for completeness. ; Colour reduction by Spinal Graphics 800,600,0,2 Global max_colours = 1023 ; can be anything, although more than 32768 will increase the number of colours! Style = 4 ; 0 = nearest colour ; 1 = floyd stienberg ; 2 = stucki ; 3 = burkes ; 4 = sierra lite ; 5 = pattern picture = LoadImage("c:\test.bmp") Global pwidth = ImageWidth(picture) Global pheight = ImageHeight(picture) Dim pal(max_colours,2) Dim bitmap(pwidth,pheight,2) ;R,G,B for each pixel in the image Dim colorList(32768) ; for counting colours Dim colorValue(32768) ; for the actual colours ; set up dithering pattern Dim matrix2(7,7) For y=0 To 7 For x=0 To 7 Read matrix2(x,y) Next Next ; dithering threashold (pattern) Data 1,49,13,61,4,52,16,64 Data 33,17,45,29,36,20,48,32 Data 9,57,5,53,12,60,8,56 Data 41,25,37,21,44,28,40,24 Data 3,51,15,63,2,50,14,62 Data 35,16,47,31,34,18,46,30 Data 11,59,7,55,10,58,6,54 Data 43,27,39,23,42,26,38,22 For t = 0 To 32768 colorValue(t) =t Next DrawBlock picture,0,0 SetBuffer ImageBuffer(picture) For x=0 To pwidth For y=0 To pheight GetColor x,y r=ColorRed() g=ColorGreen() b=ColorBlue() bitmap(x,y,0)=r bitmap(x,y,1)=g bitmap(x,y,2)=b r=r/8 g=g/8 b=b/8 colorList( (r Shl 10)+ (g Shl 5)+ b) = colorList( (r Shl 10)+ (g Shl 5)+ b) + 1 Next Next quicksort(0,32768) ; sort the colour data into assending order p=0 offset = -1 For t = 1 To 32768 If colorList(t) >0 Then If offset=-1 Then offset = t p=p+1 End If Next ; I forced some colours here, I want to make sure there are some greys ; in each palette, it helps the output, also, magenta because I need it sometimes. ; pal(0,0) = 0 : pal(0,1) = 0 : pal(0,2) = 0 ; pal(1,0) = 42 : pal(1,1) = 42 : pal(1,2) = 42 ; pal(2,0) = 85 : pal(2,1) = 85 : pal(2,2) = 85 ; pal(3,0) = 127 : pal(3,1) = 127 : pal(3,2) = 127 ; pal(4,0) = 170 : pal(4,1) = 170 : pal(4,2) = 170 ; pal(5,0) = 213 : pal(5,1) = 213 : pal(5,2) = 213 ; pal(6,0) = 255 : pal(6,1) = 255 : pal(6,2) = 255 ; pal(7,0) = 255 : pal(7,1) = 0 : pal(7,2) = 255 ; p>248 If p > max_colours Then useDither = 1 x = p/max_colours For t = 0 To max_colours s = offset + (xt) pal(t,0) = ((colorValue(s) Shr 10) And 31)8 pal(t,1) = ((colorValue(s) Shr 5) And 31)8 pal(t,2) = (ColorValue(s) And 31)8 Next Else useDither = 0 For t = 0 To p s = offset +t pal(t,0) = ((colorValue(s) Shr 10) And 31)8 pal(t,1) = ((colorValue(s) Shr 5) And 31)8 pal(t,2) = (ColorValue(s) And 31)8 Next End If ; sort the palette a little, make it look nice, not actually needed though ; simple bubble sort will do Repeat x=0 For y=0 To max_colours-1 br = (pal(y,0)+ pal(y,0)+ pal(y,1)+ pal(y,1)+ pal(y,1)+ pal(y,2))/6 br1 = (pal(y+1,0)+pal(y+1,0)+pal(y+1,1)+pal(y+1,1)+pal(y+1,1)+pal(y+1,2))/6 If br < br1 Then temp0 = pal(y+1,0) temp1 = pal(y+1,1) temp2 = pal(y+1,2) pal(y+1,0) = pal(y,0) pal(y+1,1) = pal(y,1) pal(y+1,2) = pal(y,2) pal(y,0) = temp0 pal(y,1) = temp1 pal(y,2) = temp2 x=1 End If Next Until x=0 SetBuffer FrontBuffer() t=0:x=0:y=0 For t = 0 To max_colours Color 128,128,128 Rect pwidth + 7 + (x8), 7 + (y8),9,9,1 Color pal(t,0), pal(t,1), pal(t,2) Rect pwidth + 8 + (x8), 8 + (y8),7,7,1 x=x+1 If x=16 Then x=0 y=y+1 End If Next For x=0 To pwidth For y=0 To pheight If style < 5 Then col = FindNearestColour(bitmap(x,y,0),bitmap(x,y,1),bitmap(x,y,2)) Else r=bitmap(x,y,0)+(matrix2(x Mod 8, y Mod 8)-32) g=bitmap(x,y,1)+(matrix2(x Mod 8, y Mod 8)-32) b=bitmap(x,y,2)+(matrix2(x Mod 8, y Mod 8)-32) If r>255 Then r=255 If g>255 Then g=255 If b>255 Then b=255 If r<0 Then r=0 If g<0 Then g=0 If b<0 Then b=0 col = FindNearestColour(r,g,b) End If Color pal(col,0),pal(col,1),pal(col,2) Plot x,y + pheight + 8 If useDither = 1 Then Select style Case 1 compute_disperse(x, y, 0, col) compute_disperse(x, y, 1, col) compute_disperse(x, y, 2, col) Case 2 compute_disperse2(x, y, 0, col) compute_disperse2(x, y, 1, col) compute_disperse2(x, y, 2, col) Case 3 compute_disperse3(x, y, 0, col) compute_disperse3(x, y, 1, col) compute_disperse3(x, y, 2, col) Case 4 compute_disperse4(x, y, 0, col) compute_disperse4(x, y, 1, col) compute_disperse4(x, y, 2, col) End Select End If Next Next While Not KeyHit(1) Delay 2 Wend End Function FindNearestColour(r,g,b) minDistanceSquared = 255255 + 255255 + 255255 + 1 ; furthes possible colour difference For i = 0 To max_colours rdiff = r - pal(i,0) gdiff = g - pal(i,1) bdiff = b - pal(i,2) DistanceSquared = rdiffrdiff + gdiffgdiff + bdiffbdiff If DistanceSquared < minDistanceSquared Then minDistanceSquared = DistanceSquared bestIndex = i End If Next Return bestIndex End Function Function quicksort(l,r) Local p,q,h p=l q=r x=colorList((l+r)/2) Repeat While colorList(p)<x p=p+1 Wend While x<colorList(q) q=q-1 Wend If p>q Then Exit ;SWAP------------------ h=colorList(q) colorList(q)=colorList(p) colorList(p)=h h=colorValue(q) colorValue(q)=colorValue(p) colorValue(p)=h ;---------------------- p=p+1 q=q-1 If q<0 Then Exit Forever If l<q Then a=quicksort(l,q) If p<r Then a=quicksort(p,r) Return True End Function Function plus_truncate(a, b) number = a+b If number >255 Then number = 255 Return number End Function Function minus_truncate(a, b) number = a-b If number <0 Then number = 0 Return number End Function Function compute_disperse(x, y, channel, index) ;Floyd Steinberg ; 7 ; 3 5 1 (1/16) err = bitmap(x, y, channel) - pal(index, channel) If x+1 < pwidth Then bitmap(x+1, y, channel) = plus_truncate(bitmap(x+1, y, channel), (err7)/16) End If If y+1 < pheight Then If x-1 > 0 Then bitmap(x-1, y+1, channel) = plus_truncate(bitmap(x-1, y+1, channel), (err3)/16) End If bitmap(x, y+1, channel) = plus_truncate(bitmap(x, y+1, channel), (err5)/16) If x+1 < pwidth Then bitmap(x+1, y+1, channel) = plus_truncate(bitmap(x+1, y+1, channel), err/16) End If End If End Function Function compute_disperse2(x, y, channel, index) ;Stucki ; 8 4 ; 2 4 8 4 2 ; 1 2 4 2 1 (1/42) err = bitmap(x, y, channel) - pal(index, channel) If x+1 < pwidth Then bitmap(x+1, y, channel) = plus_truncate(bitmap(x+1, y, channel), (err8)/42) If x+2 < pwidth Then bitmap(x+2, y, channel) = plus_truncate(bitmap(x+2, y, channel), (err4)/42) If y+1 < pheight Then If x-2 > 0 Then bitmap(x-2, y+1, channel) = plus_truncate(bitmap(x-2, y+1, channel), (err2)/42) If x-1 > 0 Then bitmap(x-1, y+1, channel) = plus_truncate(bitmap(x-1, y+1, channel), (err4)/42) bitmap(x, y+1, channel) = plus_truncate(bitmap(x, y+1, channel), (err8)/42) If x+1 < pwidth Then bitmap(x+1, y+1, channel) = plus_truncate(bitmap(x+1, y+1, channel), (err4)/42) If x+2 < pwidth Then bitmap(x+2, y+1, channel) = plus_truncate(bitmap(x+2, y+1, channel), (err2)/42) End If If y+2 < pheight Then If x-2 > 0 Then bitmap(x-2, y+2, channel) = plus_truncate(bitmap(x-2, y+2, channel), (err1)/42) If x-1 > 0 Then bitmap(x-1, y+2, channel) = plus_truncate(bitmap(x-1, y+2, channel), (err2)/42) bitmap(x, y+2, channel) = plus_truncate(bitmap(x, y+2, channel), (err4)/42) If x+1 < pwidth Then bitmap(x+1, y+2, channel) = plus_truncate(bitmap(x+1, y+2, channel), (err2)/42) If x+2 < pwidth Then bitmap(x+2, y+2, channel) = plus_truncate(bitmap(x+2, y+2, channel), (err1)/42) End If End Function Function compute_disperse3(x, y, channel, index) ;Burkes ; * 8 4 ; 2 4 8 4 2 (1/32) err = bitmap(x, y, channel) - pal(index, channel) If x+1 < pwidth Then bitmap(x+1, y, channel) = plus_truncate(bitmap(x+1, y, channel), (err8)/32) If x+2 < pwidth Then bitmap(x+2, y, channel) = plus_truncate(bitmap(x+2, y, channel), (err4)/32) If y+1 < pheight Then If x-2 > 0 Then bitmap(x-2, y+1, channel) = plus_truncate(bitmap(x-2, y+1, channel), (err2)/32) If x-1 > 0 Then bitmap(x-1, y+1, channel) = plus_truncate(bitmap(x-1, y+1, channel), (err4)/32) bitmap(x, y+1, channel) = plus_truncate(bitmap(x, y+1, channel), (err8)/32) If x+1 < pwidth Then bitmap(x+1, y+1, channel) = plus_truncate(bitmap(x+1, y+1, channel), (err4)/32) If x+2 < pwidth Then bitmap(x+2, y+1, channel) = plus_truncate(bitmap(x+2, y+1, channel), (err2)/32) End If End Function Function compute_disperse4(x, y, channel, index) ;Sierra - Filter Lite ; 2 ; 1 1 (1/4) err = bitmap(x, y, channel) - pal(index, channel) If x+1 < pwidth Then bitmap(x+1, y, channel) = plus_truncate(bitmap(x+1, y, channel), (err*2)/4) If y+1 < pheight Then If x-1 > 0 Then bitmap(x-1, y+1, channel) = plus_truncate(bitmap(x-1, y+1, channel), err/4) bitmap(x, y+1, channel) = plus_truncate(bitmap(x, y+1, channel), err/4) End If End Function --v -=-=- Check out my excellent homepage!
Wed, 10 Aug 2011, 08:58
CodersRule	What I was curious about... do most systems that limit you to a specific amount of colours (256) allow you to set your own colours? I had assumed you'd be stuck to a preset safe palette.
Wed, 10 Aug 2011, 09:04
Jayenkai	8-bits had specified palettes, but I'm pretty sure that most/if not all 16-bit and above systems allowed you to define your own colours.. -=-=- ''Load, Next List!''
Wed, 10 Aug 2011, 09:13
spinal	DS, GBA and SNES let you choose your own, don't know about any others but I assume most would. -=-=- Check out my excellent homepage!
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