Program to Change RGB color model to HSV color model


Given RGB color range, our task is to convert RGB color to HSV color.

RGB Color Model :
The RGB color model is an additive color model in which red, green and blue light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue.
 

HSV Color Model :
HSV – (hue, saturation, value), also known as HSB (hue, saturation, brightness), is often used by artists because it is often more natural to think about a color in terms of hue and saturation than in terms of additive or subtractive color components. HSV is a transformation of an RGB colorspace, and its components and colorimetry are relative to the RGB colorspace from which it was derived.
 



Examples :

Input : r, g, b = 45, 215, 0
Output :
h, s, v = 107.44186046511628, 100.0, 84.31372549019608


Input : r, g, v = 31, 52, 29
Output :
h, s, v = 114.78260869565217, 44.230769230769226, 20.392156862745097

Approach :

  1. Divide r, g, b by 255
  2. Compute cmax, cmin, difference
  3. Hue calculation :
    • if cmax and cmin equal 0, then h = 0
    • if cmax equal r then compute h = (60 * ((g – b) / diff) + 360) % 360
    • if cmax equal g then compute h = (60 * ((b – r) / diff) + 120) % 360
    • if cmax equal b then compute h = (60 * ((r – g) / diff) + 240) % 360
  4. Saturation computation :
    • if cmax = 0, then s = 0
    • if cmax does not equal 0 then compute s = (diff/cmax)*100
  5. Value computation :
    • v = cmax*100

 

Below is the implementation of above approach :

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# Python3 program change RGB Color
# Model to HSV Color Model
  
def rgb_to_hsv(r, g, b):
  
    # R, G, B values are divided by 255
    # to change the range from 0..255 to 0..1:
    r, g, b = r / 255.0, g / 255.0, b / 255.0
  
    # h, s, v = hue, saturation, value
    cmax = max(r, g, b)    # maximum of r, g, b
    cmin = min(r, g, b)    # minimum of r, g, b
    diff = cmax-cmin       # diff of cmax and cmin.
  
    # if cmax and cmax are equal then h = 0
    if cmax == cmin: 
        h = 0
      
    # if cmax equal r then compute h
    elif cmax == r: 
        h = (60 * ((g - b) / diff) + 360) % 360
  
    # if cmax equal g then compute h
    elif cmax == g:
        h = (60 * ((b - r) / diff) + 120) % 360
  
    # if cmax equal b then compute h
    elif cmax == b:
        h = (60 * ((r - g) / diff) + 240) % 360
  
    # if cmax equal zero
    if cmax == 0:
        s = 0
    else:
        s = (diff / cmax) * 100
  
    # compute v
    v = cmax * 100
    return h, s, v
  
  
''' Driver Code '''
# print(rgb_to_hsv(45, 215, 0))
# print(rgb_to_hsv(31, 52, 29))
  
print(rgb_to_hsv(129, 88, 47))

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Output :

(30.0, 63.56589147286821, 50.588235294117645) 


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