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Update to calculate chroma cycle values and adjust tint - to great ef…
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…fect!
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@dschmenk
dschmenk committed Dec 11, 2024
1 parent 318c893 commit 8f4b05e
Showing 1 changed file with 86 additions and 59 deletions.
145 changes: 86 additions & 59 deletions src/dhgr.tk/utils/dhgrrgb.pla
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Original file line number Diff line number Diff line change
Expand Up @@ -12,44 +12,28 @@ const GRN = 1
const BLU = 2
const MAX_RGB = 512
const MIN_RGB = -256
const CHROMA_RESET = $1010 // Magic value for neutral chroma
const CHROMA_RESET = $4040 // Magic value for neutral chroma

byte[] ntscChroma
// Emperical 0-255 R G B
byte[] = 64, 51, 125 // BLUE
byte[] = 0, 108, 64 // GREEN
byte[] = 64, 77, 3 // BROWN
byte[] = 128, 20, 64 // RED
// Calculated 0-255 R G B
byte[] = 32, 46, 120 // BLUE
byte[] = 8, 126, 32 // GREEN
byte[] = 96, 82, 8 // BROWN
byte[] = 120, 2, 96 // RED
// Averaged 0-255 R G B
byte[] = 64, 48, 128 // BLUE
byte[] = 16, 112, 64 // GREEN
byte[] = 64, 80, 0 // BROWN
byte[] = 112, 16, 64 // RED
// Idealized 0-255 R G B
byte[] = 64, 64, 128 // BLUE
byte[] = 0, 128, 64 // GREEN
byte[] = 64, 64, 0 // BROWN
byte[] = 128, 0, 64 // RED
byte[] grey2Chroma
// R G B
//byte[] = 0, 0, 0 // BLUE
//byte[] = 0, 108, 64 // GREEN
//byte[] = 0, 0, 0 // BROWN
//byte[] = 128, 20, 64 // RED
byte[] = 64, 51, 125 // BLUE
byte[] = 0, 0, 0 // GREEN
byte[] = 64, 77, 3 // BROWN
byte[] = 0, 0, 0 // RED
var sin90[] // first 90 degrees of sin in fixed s.15 format
var = 0, 571, 1143, 1714, 2285, 2855, 3425, 3993
var = 4560, 5126, 5690, 6252, 6812, 7371, 7927, 8480
var = 9032, 9580, 10125, 10668, 11207, 11743, 12275, 12803
var = 13327, 13848, 14364, 14876, 15383, 15886, 16383, 16876
var = 17364, 17846, 18323, 18794, 19260, 19720, 20173, 20621
var = 21062, 21497, 21926, 22347, 22762, 23170, 23571, 23964
var = 24351, 24730, 25101, 25465, 25821, 26169, 26509, 26841
var = 27165, 27481, 27788, 28087, 28377, 28659, 28932, 29196
var = 29451, 29697, 29935, 30163, 30381, 30591, 30791, 30982
var = 31164, 31336, 31498, 31651, 31794, 31928, 32051, 32165
var = 32270, 32364, 32449, 32523, 32588, 32643, 32688, 32723
var = 32748, 32763, 32767
byte[12] ntscChroma
byte[12] ntscCycle
byte[256] gamma = 0, 2 // Gamma correction
var brightness
var rgbErr // Running color error array
var tint = 103
byte errDiv = 3
var rgbErr // Running color error array
var arg

def min(a, b)
Expand All @@ -60,6 +44,57 @@ def max(a, b)
return a > b ?? a :: b
end

def sin(deg)#1
deg = deg % 360
if deg <= 90
return sin90[deg]
elsif deg <= 180
return sin90[180 - deg]
elsif deg <= 270
return -sin90[deg - 180]
fin
return -sin90[360 - deg]
end

def cos(deg)#1
return sin(deg + 90)
end

def luv2rgb(l, u, v)#3 // l = fix 1.7, u, v = fix s.15; return fix 0.8 * 3
var r, g, b

r = l + (v >> 7)
g = l - u / 181 - v / 181 // l + 0.7071 * u / 128 - 0.7071 * v / 128
b = l + (u >> 7)
return r, g, b
end

def calcChroma(angle)#0
var r, g, b
byte i, j

for i = 0 to 3
// Calculate and NTSC RGB for this DHGR pixel
r, g, b = luv2rgb(256, cos(angle), sin(angle))
j = ((i - 1) & 3) * 3 // Match Apple II order
ntscChroma[j + RED] = min(255, (r + 2) >> 2)
ntscChroma[((i-2)&3)*3 + GRN] = min(255, (g + 2) >> 2) // ??? why ???
ntscChroma[j + BLU] = min(255, (b + 2) >> 2)
// Next NTSC chroma pixel
angle = angle - 90
if angle > 360
angle = angle - 360
elsif angle < 0
angle = angle + 360
fin
next
//for i = 0 to 3
// puti(ntscChroma[i*3 + RED]); putc(',')
// puti(ntscChroma[i*3 + GRN]); putc(',')
// puti(ntscChroma[i*3 + BLU]); putln
//next
end

def dist(x1, y1, z1, x2, y2, z2)#2
res[t_i32] xx, yy

Expand Down Expand Up @@ -226,6 +261,7 @@ def rgbInit#0
gamma[i] = max(0, min(255, gamma[i] + brightness))
next
fin
calcChroma(tint)
// Make up for additional 1/4 chroma cycle
for i = 0 to 11
ntscChroma[i] = (ntscChroma[i] * 4) / 3
Expand Down Expand Up @@ -270,12 +306,16 @@ def rgbImportExport(rgbfile, dhgrfile)#0
if rgbPix(rgbptr, errptr, i & 3)
dhgrSet(i, j)
fin
// Map GREY1 -> GREY2
if (i & 3) == 3 and dcgrGetPixel(i >> 2, j) == 5
dhgrOp(OP_SRC)
dcgrColor(10)
dcgrPixel(i >> 2, j)
memcpy(@ntscCycle, @grey2Chroma, 12) // GREY2 chroma cycle
// Map GREY1 -> GREY2 and reduce grey streaks
if (i & 3) == 3
when dcgrGetPixel(i >> 2, j)
is 5
dhgrOp(OP_SRC)
dcgrColor(10)
dcgrPixel(i >> 2, j)
is 10
memset(@ntscCycle, CHROMA_RESET, 12)
wend
fin
rgbptr = rgbptr + 3
errptr = errptr + 3 * 2
Expand Down Expand Up @@ -326,25 +366,6 @@ if ^arg
brightness = atoi(arg + 2)
fin
break
is 'C' // Set chroma values - Empirical is default
when toupper(^(arg + 3))
is 'C' // Calculated chroma cycle
for gamma = 0 to 11
ntscChroma[gamma] = ntscChroma[gamma + 12]
next
break
is 'A' // Averageded chroma values
for gamma = 0 to 11
ntscChroma[gamma] = ntscChroma[gamma + 24]
next
break
is 'I' // Idealized chroma values
for gamma = 0 to 11
ntscChroma[gamma] = ntscChroma[gamma + 36]
next
break
wend
break
is 'E' // Set error strength
if ^arg > 2
errDiv = ^(arg + 3) - '0'
Expand All @@ -359,6 +380,12 @@ if ^arg
gamma[1] = atoi(arg + 2)
fin
break
is 'T' // Adjust chroma tint
if ^arg > 2
^(arg + 2) = ^arg - 2
tint = tint + atoi(arg + 2)
fin
break
wend
arg = argNext(arg)
loop
Expand All @@ -367,5 +394,5 @@ if ^arg
fin
return 0
fin
puts("Usage: DHGRRGB [-G#] [-B#] [-A#] [-T#] [-E#] [-C<C,I>] RGBFILE [DHGRFILE]\n")
puts("Usage: DHGRRGB [-B#] [-E#] [-G#] [-T#] RGBFILE [DHGRFILE]\n")
done

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