Python PIL - Finding Nearest Color (Rounding Colors)
Solution 1
Create a list of colors in your table (I call it colors). Sort the list by the distance to the r, g, b point you are questioning The first element in the list is the closest color
def distance(c1, c2):
(r1,g1,b1) = c1
(r2,g2,b2) = c2
return math.sqrt((r1 - r2)**2 + (g1 - g2) ** 2 + (b1 - b2) **2)
colors = list(rgb_code_dictionary.keys())
closest_colors = sorted(colors, key=lambda color: distance(color, point))
closest_color = closest_colors[0]
code = rgb_code_dictionary[closest_color]
Solution 2
Expanding on mattsap's answer:
We don't need to sort all the colours, since we're only looking for the closest. i.e. We can avoid the computationally expensive sort
and use min
instead.
We also don't need to calculate the absolute distance between the colours, since we're only interested in relative distance. i.e. We can also avoid the "square root" part of Pythagoras.
This gives:
colours = ( (255, 255, 255, "white"),
(255, 0, 0, "red"),
(128, 0, 0, "dark red"),
(0, 255, 0, "green") )
def nearest_colour( subjects, query ):
return min( subjects, key = lambda subject: sum( (s - q) ** 2 for s, q in zip( subject, query ) ) )
print( nearest_colour( colours, (64, 0, 0) ) ) # dark red
print( nearest_colour( colours, (0, 192, 0) ) ) # green
print( nearest_colour( colours, (255, 255, 64) ) ) # white
Of course, once you consider different colour spaces and the contributions of each colour component to its perception of the human eye, there's a whole rabbit hole to go down, as per this question, but that's probably overly overkill for most cases.
Rontron
Updated on June 04, 2022Comments
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Rontron about 2 years
There is a game called Roblox, in which the player makes the game, usually of lego-looking bricks.
In Roblox, for the Brick colors, you can use typical RGB values, but that'd require an additional element that is not very efficient when it comes to file size. Instead of using RGB values, BrickColor is much more economic in file size. It uses an integer to be interpreted as a certain color. Here is what I mean:
Here is a snippet of my code:
import Image f = raw_input('Image:\n') im = Image.open(f) rgb_im = im.convert('RGB') r, g, b = rgb_im.getpixel((x, y))
In my program, I need to find the color code closest to an RGB value.
How might this be accomplished?
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Rontron over 8 yearsI got it so it finds the nearest RGB value in a table of RGB values, but how would I translate that into finding the color integer (as in the color codes I linked in my question)?
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mattsap over 8 yearsEach RGB value should be mapped to an integer as their color code. You can create a dictionary where the key is the RGB value and the value is the integer. I'll note that the RGB value must be a tuple, not a list in order for it to be a key in the dictionary. See stackoverflow.com/questions/1938614/…
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Rontron over 8 yearsThanks, I got it to work by formatting the colors table like so:
{(27,42,53):26, (242,243,243):1, (163,162,165):194, etc.}
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horcrux about 3 yearsThis is not a very good function for color similarity, see also stackoverflow.com/questions/5392061