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06-29-2022, 03:35 AM
(This post was last modified: 06-30-2022, 01:26 PM by James D Jarvis.)
CMYK or process color is the model used in print. I spent years doing print work and just find it easier to mix colors using that color model.
Each color is expressed as a % of Cyan C, Magenta M, Yellow Y, and Black K
White is 0,0,0,0
Red is 0,100,80,0 to 0,100,100,0
Greys are 0,0,0,1 to 99 or C,M & Y set to the same value from 1 to 99
Code: (Select All) Screen _NewImage(640, 480, 32)
Color _RGB32(0, 0, 0), _RGB32(255, 255, 255)
Cls
'a simple demo of the color values
Do
Print "Enter C,M,Y,K"
Input c, m, y, k
k& = cmyk~&(c, m, y, k)
Line (200, 200)-(400, 400), k&, BF
Loop Until c = -100
Function cmyk~& (c As Long, m As Long, y As Long, k As Long)
' CMYK process color Cyan, Magenta, Yellow, Black each expressed as a percent from 0 to 100
r = 255 * (100 - c)
r = (r / 100) * ((100 - k) / 100)
g = 255 * (100 - m)
g = (g / 100) * ((100 - k) / 100)
b = 255 * (100 - y)
b = (b / 100) * ((100 - k) / 100)
cmyk~& = _RGB32(r, g, b)
End Function
Posts: 671
Threads: 143
Joined: Apr 2022
Reputation:
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A few additional functions and subs for manipulating CMYK color.
Code: (Select All) Screen _NewImage(640, 480, 32)
Color _RGB32(0, 0, 0), _RGB32(255, 255, 255)
Cls
Print "Just a handful of examples, there are several functions and subs here to"
Print " manipulate and monitor CMYK colors"
Print "mixing colors CMYK(0,70,50,0) and CMYK(80,0,0,0)"
kl& = mix_cmyk~&(cmyk~&(0, 70, 50, 0), cmyk~&(80, 0, 0, 0))
Line (400, 50)-(450, 100), cmyk~&(0, 70, 50, 0), BF
Line (450, 50)-(500, 100), cmyk~&(80, 0, 0, 0), BF
Line (500, 50)-(600, 100), kl&, BF
Locate 10, 1: Print "Lighten and darken CMYK(50,50,0,0) by 25%"
kl& = cmyk~&(50, 50, 0, 0)
lk& = kl&: dk& = kl&
lighten_cmyk lk&, 25
darken_cmyk dk&, 25
Line (400, 150)-(600, 200), kl&, BF
Line (400, 200)-(500, 250), lk&, BF
Line (500, 200)-(600, 250), dk&, BF
Locate 18, 1: Print "Adding 60 to Yellow channel in each of those."
add_yellow kl&, 60
add_yellow lk&, 60
add_yellow dk&, 60
Line (400, 300)-(600, 350), kl&, BF
Line (400, 350)-(500, 400), lk&, BF
Line (500, 350)-(600, 400), dk&, BF
Function cmyk~& (c As Long, m As Long, y As Long, k As Long)
' CMYK process color Cyan, Magenta, Yellow, Black each expressed as a percent from 0 to 100
r = 255 * (100 - c)
r = (r / 100) * ((100 - k) / 100)
g = 255 * (100 - m)
g = (g / 100) * ((100 - k) / 100)
b = 255 * (100 - y)
b = (b / 100) * ((100 - k) / 100)
cmyk~& = _RGB32(r, g, b)
End Function
Function get_c (klr As _Unsigned Long)
r = _Red32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100)
get_c = c
End Function
Function get_m (klr As _Unsigned Long)
g = _Green32(klr)
m = Int((1 + 1 / 255 - (g / 255)) * 100)
get_m = m
End Function
Function get_y (klr As _Unsigned Long)
b = _Blue32(klr)
y = Int((1 + 1 / 255 - (b / 255)) * 100)
get_y = y
End Function
Function get_k (klr As _Unsigned Long)
r = _Red32(klr)
g = _Green32(klr)
b = _Blue32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100)
m = Int((1 + 1 / 255 - (g / 255)) * 100)
y = Int((1 + 1 / 255 - (b / 255)) * 100)
If c = m And m = y Then
k = m
Else
k = 0
End If
get_k = k
End Function
Sub get_cmyk (klr As _Unsigned Long, c, m, y, k)
r = _Red32(klr)
g = _Green32(klr)
b = _Blue32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100)
m = Int((1 + 1 / 255 - (g / 255)) * 100)
y = Int((1 + 1 / 255 - (b / 255)) * 100)
'the dirty little secret of CMYK in a additive light space is black disappears into CMY values
'theres always a CMY vlaue that replicates a CMYK color with no K required but...
'in print getting rid of K would be a disaster but on a monitor it makes no difference
If c = m And m = y Then
k = m
m = 0
y = 0
c = 0
Else
k = 0
End If
End Sub
Sub lighten_cmyk (klr As _Unsigned Long, pp)
'lightens all four CMYK color channels by the same relative %
r = _Red32(klr)
g = _Green32(klr)
b = _Blue32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100)
m = Int((1 + 1 / 255 - (g / 255)) * 100)
y = Int((1 + 1 / 255 - (b / 255)) * 100)
If c = m And m = y Then
k = m
m = 0
y = 0
c = 0
Else
k = 0
End If
c = c * ((100 - pp) / 100)
m = m * ((100 - pp) / 100)
y = y * ((100 - pp) / 100)
k = k * ((100 - pp) / 100)
klr = cmyk~&(c, m, y, k)
End Sub
Sub darken_cmyk (klr As _Unsigned Long, pp)
'lightens all four CMYK color channels by the same relative %
r = _Red32(klr)
g = _Green32(klr)
b = _Blue32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100)
m = Int((1 + 1 / 255 - (g / 255)) * 100)
y = Int((1 + 1 / 255 - (b / 255)) * 100)
If c = m And m = y Then
k = m
m = 0
y = 0
c = 0
Else
k = 0
End If
c = c * ((100 + pp) / 100): If c > 100 Then c = 100
m = m * ((100 + pp) / 100): If m > 100 Then m = 100
y = y * ((100 + pp) / 100): If y > 100 Then y = 100
k = k * ((100 + pp) / 100): If k > 100 Then k = 100
klr = cmyk~&(c, m, y, k)
End Sub
Sub add_cyan (klr As _Unsigned Long, cc)
r = _Red32(klr)
g = _Green32(klr)
b = _Blue32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100) + cc
m = Int((1 + 1 / 255 - (g / 255)) * 100)
y = Int((1 + 1 / 255 - (b / 255)) * 100)
If c = m And m = y Then
k = m
m = 0
y = 0
c = 0
Else
k = 0
End If
If c > 100 Then c = 100
If c < 0 Then c = 0
klr = cmyk~&(c, m, y, k)
End Sub
Sub add_magenta (klr As _Unsigned Long, mm)
r = _Red32(klr)
g = _Green32(klr)
b = _Blue32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100)
m = Int((1 + 1 / 255 - (g / 255)) * 100) + mm
y = Int((1 + 1 / 255 - (b / 255)) * 100)
If c = m And m = y Then
k = m
m = 0
y = 0
c = 0
Else
k = 0
End If
If m > 100 Then m = 100
If m < 0 Then m = 0
klr = cmyk~&(c, m, y, k)
End Sub
Sub add_yellow (klr As _Unsigned Long, yy)
r = _Red32(klr)
g = _Green32(klr)
b = _Blue32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100)
m = Int((1 + 1 / 255 - (g / 255)) * 100)
y = Int((1 + 1 / 255 - (b / 255)) * 100) + yy
If c = m And m = y Then
k = m
m = 0
y = 0
c = 0
Else
k = 0
End If
If y > 100 Then y = 100
If y < 0 Then y = 0
klr = cmyk~&(c, m, y, k)
End Sub
Sub add_black (klr As _Unsigned Long, kk)
r = _Red32(klr)
g = _Green32(klr)
b = _Blue32(klr)
c = Int((1 + 1 / 255 - (r / 255)) * 100)
m = Int((1 + 1 / 255 - (g / 255)) * 100)
y = Int((1 + 1 / 255 - (b / 255)) * 100) + yy
If c = m And m = y Then
k = m + kk
m = 0
y = 0
c = 0
Else
k = 0 + kk
End If
If k > 100 Then k = 100
If k < 0 Then k = 0
klr = cmyk~&(c, m, y, k)
End Sub
Function mix_cmyk~& (klr1 As _Unsigned Long, klr2 As _Unsigned Long)
'evenly mix two colors by averaging each channel
r1 = _Red32(klr1)
g1 = _Green32(klr1)
b1 = _Blue32(klr1)
c1 = Int((1 + 1 / 255 - (r1 / 255)) * 100)
m1 = Int((1 + 1 / 255 - (g1 / 255)) * 100)
y1 = Int((1 + 1 / 255 - (b1 / 255)) * 100)
If c1 = m1 And m1 = y1 Then
k1 = m1
m1 = 0
y1 = 0
c1 = 0
Else
k1 = 0
End If
r2 = _Red32(klr2)
g2 = _Green32(klr2)
b2 = _Blue32(klr2)
c2 = Int((1 + 1 / 255 - (r2 / 255)) * 100)
m2 = Int((1 + 1 / 255 - (g2 / 255)) * 100)
y2 = Int((1 + 1 / 255 - (b2 / 255)) * 100)
If c2 = m2 And m2 = y2 Then
k2 = m2
m2 = 0
y2 = 0
c2 = 0
Else
k2 = 0
End If
c = Int((c1 + c2) / 2)
m = Int((m1 + m2) / 2)
y = Int((y1 + y2) / 2)
k = Int((k1 + k2) / 2)
mix_cmyk~& = cmyk~&(c, m, y, k)
End Function
Function add_cmyk~& (klr1 As _Unsigned Long, klr2 As _Unsigned Long)
'add all the channels in both colors max value wil be 100 per channel
r1 = _Red32(klr1)
g1 = _Green32(klr1)
b1 = _Blue32(klr1)
c1 = Int((1 + 1 / 255 - (r1 / 255)) * 100)
m1 = Int((1 + 1 / 255 - (g1 / 255)) * 100)
y1 = Int((1 + 1 / 255 - (b1 / 255)) * 100)
If c1 = m1 And m1 = y1 Then
k1 = m1
m1 = 0
y1 = 0
c1 = 0
Else
k1 = 0
End If
r2 = _Red32(klr2)
g2 = _Green32(klr2)
b2 = _Blue32(klr2)
c2 = Int((1 + 1 / 255 - (r2 / 255)) * 100)
m2 = Int((1 + 1 / 255 - (g2 / 255)) * 100)
y2 = Int((1 + 1 / 255 - (b2 / 255)) * 100)
If c2 = m2 And m2 = y2 Then
k2 = m2
m2 = 0
y2 = 0
c2 = 0
Else
k2 = 0
End If
c = c1 + c2: If c > 100 Then c = 100
m = m1 + m2: If m > 100 Then m = 100
y = y1 + y2: If y > 100 Then y = 100
k = k1 + k2: If k > 100 Then k = 100
add_cmyk~& = cmyk~&(c, m, y, k)
End Function
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