Created
October 5, 2019 18:21
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Functions to convert a NumPy array from RGB to HSL or vice versa
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def rgb_to_hsl_arr(image_data): | |
return np.apply_along_axis(rgb_to_hsl, -1, image_data) | |
def hsl_to_rgb_arr(image_data): | |
return np.apply_along_axis(hsl_to_rgb, -1, image_data) | |
def rgb_to_hsl(rgb_as_float): | |
r, g, b = rgb_as_float | |
high = max(r, g, b) | |
low = min(r, g, b) | |
h, s, v = ((high + low) / 2,)*3 | |
if high == low: | |
h = 0.0 | |
s = 0.0 | |
else: | |
d = high - low | |
l = (high + low) / 2 | |
s = d / (2 - high - low) if l > 0.5 else d / (high + low) | |
h = { | |
r: (g - b) / d + (6 if g < b else 0), | |
g: (b - r) / d + 2, | |
b: (r - g) / d + 4, | |
}[high] | |
h /= 6 | |
return [h, s, v] | |
def hsl_to_rgb(hsl_as_float): | |
h, s, l = hsl_as_float | |
def hue_to_rgb(p, q, t): | |
t += 1 if t < 0 else 0 | |
t -= 1 if t > 1 else 0 | |
if t < 1/6: return p + (q - p) * 6 * t | |
if t < 1/2: return q | |
if t < 2/3: p + (q - p) * (2/3 - t) * 6 | |
return p | |
if s == 0: | |
r, g, b = l, l, l | |
else: | |
q = l * (1 + s) if l < 0.5 else l + s - l * s | |
p = 2 * l - q | |
r = hue_to_rgb(p, q, h + 1/3) | |
g = hue_to_rgb(p, q, h) | |
b = hue_to_rgb(p, q, h - 1/3) | |
return [r, g, b] |
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