Convert HSV to RGB

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1

Hello developers,

I have an HSV value (according to docs) which is [8.67, 0.98, 0.63] and I cant convert it to RGB which should be [208, 89, 24]

import colorsys

value_hsv =  [8.67, 0.98, 0.63]
value_rgb = colorsys.hsv_to_rgb(value_hsv[0], value_hsv[1], value_hsv[2])

print value_rgb[0]*255, value_rgb[1]*255, value_rgb[2]*255

Any ideas?

2

I don’t know, but the examples in the docs suggest that the HSV values should be in the range of 0 to 1. You have H = 8.67.

Edit this SO comment would agree, 0-1 ranges: python - RGB to HSV wrong in colorsys? - Stack Overflow

3

Yeah colorsys wants everything in 0-1 range. We wrote a bunch of wrapper functions to deal with different systems preferring different ranges to get stuff in and out properly.
Was a bit of a pain.

4

value_hsv = [8.67/360, 0.98, 0.63] gives [160, 25, 3] which is also far from RGB!

5

This looks to be the correct code for the conversion - im trying to understand what YIQ space is seeing as some of the values can be negative…

Based on this site:

Tested against this site:

import math

def hsv2rgb(h, s, v):
    
    """HSV to RGB
    
    :param float h: 0.0 - 360.0
    :param float s: 0.0 - 1.0
    :param float v: 0.0 - 1.0
    :return: rgb 
    :rtype: list
    
    """
    
    c = v * s
    x = c * (1 - abs(((h/60.0) % 2) - 1))
    m = v - c
    
    if 0.0 <= h < 60:
        rgb = (c, x, 0)
    elif 0.0 <= h < 120:
        rgb = (x, c, 0)
    elif 0.0 <= h < 180:
        rgb = (0, c, x)
    elif 0.0 <= h < 240:
        rgb = (0, x, c)
    elif 0.0 <= h < 300:
        rgb = (x, 0, c)
    elif 0.0 <= h < 360:
        rgb = (c, 0, x)
        
    return list(map(lambda n: (n + m) * 255, rgb))
        
# Example
print(hsv2rgb(57, 1, .5))

Running this from RGB to HSL in the colorsys module:

import colorsys

print(colorsys.rgb_to_hsv(208/255., 89/255., 24/255.))

gives us: (0.0588768115942029, 0.8846153846153846, 0.8156862745098039)

1 Like
6

There is a Bifrost compound doing that.
https://area.autodesk.com/downloads/hsv-to-rgb/

hsvrgb
hsvrgb1295×924 105 KB