We make a version of the artist's color wheel which shows how any known color and shade of color can be obtained by judicious mixing of the three primary colors of red, green and blue.
We have made a set of twelve color lists. Each list represents the color that results when you mix colors on either side of it, except for the primary colors of red, green, and blue. The other critical addition to the code is the function rotate(xya, xyb, theta_deg_incr) that is used to rotate the color wedge pattern to a new chosen position around a central point. As some trigonometry is used to do the rotation, the math module needs to be imported at the top of the code. Each segment forms part of the complete circle of color variations. The following screenshot shows a version of Isaac Newton's Color Wheel.
# primary_color_wheel_1.py
#>>>>>>>>>>>>>>>>>>>>>
from Tkinter import *
import math
root = Tk()
root.title("Color wheel segments")
cw = 400 # canvas width
ch = 400 # canvas height
chart_1 = Canvas(root, width=cw, height=ch, background="black")
chart_1.grid(row=0, column=0)
theta_deg = 0.0
color mixingx_orig = 200
y_orig = 200
x_width = 40
y_hite = 160
xy0 = [x_orig, y_orig]
xy1 = [x_orig - x_width, y_orig - y_hite]
xy2 = [x_orig + x_width, y_orig - y_hite ]
wedge =[ xy0, xy1 , xy2 ]
width= 40 #standard disk diameter
hite = 80 # median wedge height.
hFac = [0.25, 0.45, 0.75, 1.2, 1.63, 1.87, 2.05] # Radial # factors
wFac = [ 0.2, 0.36, 0.6, 1.0, 0.5, 0.3, 0.25] # disk # diameter factors
x_DiskRot = [1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0] # rotational coordinates
y_DiskRot = [1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0]
#RED
kulaRed = ["#000000", "#6e0000", "#a00000", "#ff0000",
"#ff5050", "#ff8c8c", "#ffc8c8", "#440000" ]
# Khaki
kulaRRedGreen = ["#000000", "#606000", "#8f9f00", "#b3b300",
"#d6d600", "#dbdb30", "#dbdb77", "#3e2700" ]
# Yellow
kulaRedGreen = ["#000000", "#6e6e00", "#a0a000", "#ffff00",
"#ffff50", "#ffff8c", "#ffffc8", "#444400" ]
# Orange
kulaRedGGreen = ["#000000", "#493100", "#692f00", "#a25d00",
"#ff8300", "#ffa55a", "#ffb681", "#303030" ]
# Green
kulaGreen = ["#000000", "#006e00", "#00a000", "#00ff00",
"#50ff50", "#8cff8c", "#c8ffc8", "#004400" ]
# Dark green
kulaGGreenBlue = ["#000000", "#003227", "#009358", "#00a141",
"#00ff76", "#72ff99", "#acffbf", "#003a1d" ]
# Cyan
kulaGreenBlue = ["#000000", "#006e6e", "#00a0a0", "#00ffff",
"#50ffff", "#8cffff", "#c8ffff", "#004444" ]
# Steel Blue
kulaGreenBBlue = ["#000000", "#002c46", "#00639c", "#008cc8",
"#00b6ff", "#7bb6ff", "#addfff", "#001a27" ]
# Blue
kulaBlue = ["#000000", "#00006e", "#0000a0", "#0000ff",
"#5050ff", "#8c8cff", "#c8c8ff", "#000044" ]
# Purple
kulaBBlueRed = ["#000000", "#470047", "#6c00a2", "#8f00ff",
"#b380ff", "#d8b3ff", "#f1deff", "#200031" ]
# Crimson
kulaBlueRed = ["#000000", "#6e006e", "#a000a0", "#ff00ff",
"#ff50ff", "#ff8cff", "#ffc8ff", "#440044" ]
# Magenta
kulaBlueRRed = ["#000000", "#380023", "#80005a", "#b8007b",
"#ff00a1", "#ff64c5", "#ff89ea", "#2e0018" ]
# ROTATE
def rotate(xya, xyb, theta_deg_incr): #xya, xyb are 2 component # points
# General purpose point rotation function
theta_rad = math.radians(theta_deg_incr)
a_radian = math.atan2( (xyb[1] - xya[1]) , (xyb[0] - xya[0]) )
a_length = math.sqrt( (xyb[1] - xya[1])**2 + (xyb[0] - xya[0])**2)
theta_rad += a_radian
theta_deg = math.degrees(theta_rad)
new_x = a_length * math.cos(theta_rad)
new_y = a_length * math.sin(theta_rad)
return new_x, new_y, theta_deg # theta_deg = post # rotation angle
# GENL. SEGMENT BACKGROUND FUNCTION
defsegmentBackground(kula, angle, xy1, xy2):
xy_new1 = rotate(xy0, xy1, angle) # rotate xy1
xy1 =[ xy_new1[0] + xy0[0], xy_new1[1] + xy0[1] ]
xy_new2 = rotate(xy0, xy2, angle) # rotate xy2
xy2 =[ xy_new2[0] + xy0[0], xy_new2[1] + xy0[1] ]
wedge =[ xy0, xy1 , xy2 ]
chart_1.create_polygon(wedge,fill=kula[7])
# GENL. COLOR DISKS FUNCTION
defcolorDisks( kula, angle):
global hite, width, hFac, wFac
for i in range(0, 7): # green segment disks
xya = [xy0[0], xy0[1] - hite * hFac[i] ] # position of point for # rotation
xy_new1 = rotate(xy0, xya, angle) # rotate xya
# NEW CIRCLE CENTERS AFTER ROTATION OF CENTERLINE
x0_disk = xy_new1[0] + xy0[0] - width*wFac[i]/2
y0_disk = xy_new1[1] + xy0[1] + width * wFac[i]/2
xya = [x0_disk, y0_disk] # BOTTOM LEFT
x1_disk = xy_new1[0] + xy0[0] + width*wFac[i]/2
y1_disk = xy_new1[1] + xy0[1] - width * wFac[i]/2
xyb = [x1_disk, y1_disk] #TOP RIGHT
chart_1.create_oval(xya ,xyb , fill=kula[i], outline=kula[i])
for i in range(0,12):
if i==0:
angle = 0.0
kula = kulaRed
if i==1:
angle = 30.0
kula = kulaRRedGreen
if i==2:
angle = 60.0
kula = kulaRedGreen
if i==3:
angle = 90.0
kula = kulaRedGGreen
if i==4:
angle = 120.0
kula = kulaGreen
if i==5:
angle = 150.0
kula = kulaGGreenBlue
if i==6:
angle = 180.0
kula = kulaGreenBlue
if i==7:
angle = 210.0
kula = kulaGreenBBlue
if i==8:
angle = 240.0
kula = kulaBlue
if i==9:
angle = 270.0
kula = kulaBBlueRed
if i==10:
angle = 300.0
kula = kulaBlueRed
if i==11:
angle = 330.0
kula = kulaBlueRRed
if i==12:
angle = 360.0
kula = kulaBlueRRed
segmentBackground( kula, angle, xy1, xy2)
colorDisks( kula, angle)
root.mainloop()
For each color segment of the wheel a list of shaded hex color values was included in the list. The exact amounts of red, green, and blue to add together for colors that require portions of all three primary colors is not a simple matter. In general, to lighten a color we need to add extra amounts of the color that doesn't even belong to the target color. For example, if we want a pale yellow we need equal amounts of red and green together. But to make the yellow paler we need to add some blue. To darken the yellow we make sure there is no blue at all and we combine smaller but equal proportions of red and blue.
Mixing colors is an art as much as a science. Astute color mixing demands practice and experimentation. Mixing colors numerically does not come naturally to the human brain. We need some visual-numerical-computational tools to help us mix colors. But the math must be invisible. It must not hamper the artist. We want the equivalent of tubes of primary colors and a palette to mix them on. Our palette must automatically display the numerical values that represent the colors we have mixed so that we can record and incorporate them into Python code. It would be cool if our palette could be placed on top of or next to portions of existing pictures so that we could match existing colors in the picture. Would that be a nice thing to have? Well, the next recipe tries to grant that wish.