def rgb2hsi(rgb: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert RGB to Hue Saturation Intensity
:param rgb:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(rgb.shape, 3)
big_m, little_m, chroma = _compute_chroma(rgb, axis)
inds = construct_component_inds(axis, rgb.ndim, 3)
hsi = np.zeros(rgb.shape)
hsi[inds[0]] = _compute_rgb_hue(rgb, big_m, little_m, chroma, axis)
hsi[inds[2]] = np.mean(rgb, axis=axis, keepdims=True)
i_nz = hsi[inds[2]] != 0 # type: np.ndarray
if little_m.ndim < i_nz.ndim:
# This only happens in the 1D case
little_m = little_m[slice(None), np.newaxis]
if np.any(i_nz):
hsi[inds[1]][i_nz] = 1 - little_m[i_nz] / hsi[inds[2]][i_nz]
return hsi
def hsl2rgb(hsl: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert from Hue Saturation Lightness (HSL) to RGB
:type hsl: np.ndarray
:param hsl:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(hsl.shape, 3)
inds = construct_component_inds(axis, hsl.ndim, 3)
chroma = ((1. - np.abs(2. * hsl[inds[2]] - 1.)) * hsl[inds[1]]
) # type: np.ndarray
h_prime = hsl[inds[0]] / 60.
x = chroma * (1 - np.abs(np.mod(h_prime, 2) - 1))
rgb1 = _compute_rgb1(hsl.shape, inds, h_prime, x, chroma)
little_m = hsl[inds[2]] - chroma / 2.
if little_m.ndim > rgb1.ndim:
# This only happens if hsl is 1-D
return rgb1 + little_m[0]
else:
return rgb1 + little_m
def xyz2xyy(xyz: np.ndarray,
*,
axis: int = None,
illuminant: Illuminant = None,
observer: Observer = None) -> np.ndarray:
"""
Convert XYZ to xyY
:param xyz:
:param axis:
:param illuminant:
:param observer:
:return:
"""
if axis is None:
axis = get_matching_axis(xyz.shape, 3)
if illuminant is None:
illuminant = get_default_illuminant()
if observer is None:
observer = get_default_observer()
inds = construct_component_inds(axis, xyz.ndim, 3)
denominator = np.sum(xyz, axis, keepdims=True)
nzd = denominator != 0
xyy = np.zeros(xyz.shape)
if np.any(nzd):
xyy[inds[0]][nzd] = xyz[inds[0]][nzd] / denominator[nzd]
xyy[inds[1]][nzd] = xyz[inds[1]][nzd] / denominator[nzd]
xyy[inds[2]] = xyz[inds[1]]
if not np.all(nzd):
# For any point that is pure black (X=Y=Z=0), give it the
# chromaticity of the white point of the specified illuminant and
# observer.
white_point = illuminant.get_white_point(observer)
# to prevent infinite recursion, ensure that the white point is
# non-black
if white_point[1] > 0:
zd = np.logical_not(nzd)
white_point_xyy = xyz2xyy(white_point,
illuminant=illuminant,
observer=observer)
xyy[inds[0]][zd] = white_point_xyy[0]
xyy[inds[1]][zd] = white_point_xyy[1]
return xyy
def lab2lch(lab: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert L*a*b* to LCh
:param lab:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(lab.shape, 3)
inds = construct_component_inds(axis, lab.ndim, 3)
lch = np.zeros(lab.shape)
lch[inds[0]] = lab[inds[0]]
lch[inds[1]] = np.sqrt(lab[inds[1]]**2 + lab[inds[2]]**2)
lch[inds[2]] = np.mod(
(180 / np.pi) * np.arctan2(lab[inds[2]], lab[inds[1]]), 360.)
return lch
def rgb2hcy(rgb: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert from RGB to Hue, Chroma, Luma (Y'_601)
:param rgb:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(rgb.shape, 3)
big_m, little_m, chroma = _compute_chroma(rgb, axis)
inds = construct_component_inds(axis, rgb.ndim, 3)
hcy = np.zeros(rgb.shape)
hcy[inds[0]] = _compute_rgb_hue(rgb, big_m, little_m, chroma, axis)
hcy[inds[1]] = chroma
hcy[inds[2]] = 0.299 * rgb[inds[0]] + 0.587 * rgb[inds[1]] + 0.114 * rgb[
inds[2]]
return hcy
def xyy2xyz(xyy, *, axis: int = None) -> np.ndarray:
"""
converts from xyY to XYZ
:param xyy:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(xyy.shape, 3)
inds = construct_component_inds(axis, len(xyy.shape), 3)
# Determine where y iz 0 so we don't divide by it
nzy = np.nonzero(xyy[inds[1]])
xyz = np.zeros(xyy.shape)
xyz[inds[0]][nzy] = xyy[inds[0]][nzy] * xyy[inds[2]][nzy] / xyy[
inds[1]][nzy]
xyz[inds[1]][nzy] = xyy[inds[2]][nzy]
xyz[inds[2]][nzy] = ((1 - xyy[inds[0]][nzy] - xyy[inds[1]][nzy]) *
xyy[inds[2]][nzy] / xyy[inds[1]][nzy])
return xyz
def hcy2rgb(hcy: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
:param hcy:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(hcy.shape, 3)
inds = construct_component_inds(axis, hcy.ndim, 3)
h_prime = hcy[inds[0]] / 60.
x: np.ndarray = hcy[inds[1]] * (1 - np.abs(np.mod(h_prime, 2) - 1))
rgb1 = _compute_rgb1(hcy.shape, inds, h_prime, x, hcy[inds[1]])
little_m: np.ndarray = hcy[inds[2]] - (
0.299 * rgb1[inds[0]] + 0.587 * rgb1[inds[1]] + 0.114 * rgb1[inds[2]])
if little_m.ndim > rgb1.ndim:
# This only happens in the 1D case
return rgb1 + little_m[0]
else:
return rgb1 + little_m
def hsv2rgb(hsv: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert from HSV to RGB
:param hsv:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(hsv.shape, 3)
inds = construct_component_inds(axis, hsv.ndim, 3)
chroma = hsv[inds[1]] * hsv[inds[2]]
h_prime = hsv[inds[0]] / 60.
x = chroma * (1. - np.abs(np.mod(h_prime, 2.) - 1)) # type: np.ndarray
rgb1 = _compute_rgb1(hsv.shape, inds, h_prime, x, chroma)
little_m = hsv[inds[2]] - chroma
if little_m.ndim > rgb1.ndim:
# This only happens in the 1D case
return rgb1 + little_m[0]
else:
return rgb1 + little_m
def lab2xyzr(lab: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert LAB to normalized XYZ
:param lab:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(lab.shape, 3)
inds = construct_component_inds(axis, len(lab.shape), 3)
fxyz = np.zeros(lab.shape)
fxyz[inds[1]] = (lab[inds[0]] + 16) / 116
fxyz[inds[0]] = lab[inds[1]] / 500 + fxyz[inds[1]]
fxyz[inds[2]] = fxyz[inds[1]] - lab[inds[2]] / 200
is_small = fxyz <= (LAB_EPS**(1.0 / 3.0))
is_big = np.logical_not(is_small)
xyzr = np.zeros(lab.shape)
xyzr[is_big] = fxyz[is_big]**3.0
xyzr[is_small] = (116 * fxyz[is_small] - 16) / LAB_KAPPA
return xyzr
def rgb2hsv(rgb: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert from RGB to Hue Saturation Value (HSV)
:param rgb:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(rgb.shape, 3)
big_m, little_m, chroma = _compute_chroma(rgb, axis)
inds = construct_component_inds(axis, rgb.ndim, 3)
hsv = np.zeros(rgb.shape)
hsv[inds[0]] = _compute_rgb_hue(rgb, big_m, little_m, chroma, axis)
hsv[inds[2]] = big_m
big_m_nz = big_m != 0
hsv[inds[1]][big_m_nz] = chroma[big_m_nz] / big_m[big_m_nz]
return hsv
def _compute_rgb_hue(rgb: np.ndarray, big_m, little_m, chroma,
axis: int) -> np.ndarray:
""" Compute the RGB Hue. This is the same for HSV and HSL """
inds = construct_component_inds(axis, rgb.ndim, 3)
r = rgb[inds[0]]
g = rgb[inds[1]]
b = rgb[inds[2]]
if chroma.ndim < r.ndim:
# this will only happen when chroma is 1-D
chroma = chroma[(slice(None), np.newaxis)]
ch_is_nz = chroma != 0.
m_is_r = np.logical_and(big_m == r, ch_is_nz)
m_is_g = np.logical_and(big_m == g, ch_is_nz)
m_is_b = np.logical_and(big_m == b, ch_is_nz)
h_prime = np.zeros(r.shape)
if np.any(m_is_r):
h_prime[m_is_r] = np.mod((g[m_is_r] - b[m_is_r]) / chroma[m_is_r] + 6.,
6.)
if np.any(m_is_g):
h_prime[m_is_g] = (b[m_is_g] - r[m_is_g]) / chroma[m_is_g] + 2.
if np.any(m_is_b):
h_prime[m_is_b] = (r[m_is_b] - g[m_is_b]) / chroma[m_is_b] + 4.
return 60. * h_prime
def hsi2rgb(hsi: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert Hue Saturation Intensity (HSI) to RGB
:param hsi:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(hsi.shape, 3)
inds = construct_component_inds(axis, hsi.ndim, 3)
h_prime = hsi[inds[0]] / 60.
z = 1 - np.abs(np.mod(h_prime, 2.) - 1)
chroma = 3 * hsi[inds[2]] * hsi[inds[1]] / (1 + z) # type: np.ndarray
x = chroma * z
rgb1 = _compute_rgb1(hsi.shape, inds, h_prime, x, chroma)
little_m = hsi[inds[2]] * (1 - hsi[inds[1]]) # type: np.ndarray
if little_m.ndim > rgb1.ndim:
# This only happens in the 1D case
return rgb1 + little_m[0]
else:
return rgb1 + little_m
def rgb2hsl(rgb: np.ndarray, *, axis: int = None) -> np.ndarray:
"""
Convert RGB to Hue Saturation Lightness
:param rgb:
:param axis:
:return:
"""
if axis is None:
axis = get_matching_axis(rgb.shape, 3)
big_m, little_m, chroma = _compute_chroma(rgb, axis)
inds = construct_component_inds(axis, rgb.ndim, 3)
hsl = np.zeros(rgb.shape)
hsl[inds[0]] = _compute_rgb_hue(rgb, big_m, little_m, chroma, axis)
l = 0.5 * (big_m + little_m)
hsl[inds[2]] = l
l_lt_one = l < 1.
if np.any(l_lt_one):
hsl[inds[1]][l_lt_one] = ((big_m[l_lt_one] - little_m[l_lt_one]) /
(1. - np.abs(2 * l[l_lt_one] - 1)))
return hsl