def hue(im1, im2):
"""Creates a color with the hue of the source color
and the saturation and luminosity of the backdrop color.
The hue formula is defined as:
B(Cb, Cs) = SetLum(SetSat(Cs, Sat(Cb)), Lum(Cb))
See the W3C document:
https://www.w3.org/TR/compositing-1/#blendinghue
Arguments:
im1: A backdrop image.
im2: A source image.
Returns:
The output image.
"""
r1, g1, b1 = im1.split() # Cb
r2, g2, b2 = im2.split() # Cs
lum_cb = lum_im(im1) # Lum(Cb)
bands = ImageMath.eval('f((r1, g1, b1), (r2, g2, b2), lum_cb)',
f=_hue,
r1=r1,
g1=g1,
b1=b1,
r2=r2,
g2=g2,
b2=b2,
lum_cb=lum_cb)
bands = [_convert(band, 'L').im for band in bands]
return Image.merge('RGB', bands)
def _color_dodge_image_math(cb, cs_inv):
"""Returns ImageMath operands for color dodge blend mode"""
cb = _float(cb)
cs_inv = _float(cs_inv)
cm = ((cb != 0) * (cs_inv == 0) + (cb / cs_inv)) * 255
return _convert(cm, 'L')
def test_set_lum():
im1 = util.fill((1, 1), [0, 128, 255])
im2 = util.fill((1, 1), [128, 128, 128])
r1, g1, b1 = im1.split()
r2, g2, b2 = im2.split()
c1 = '(float(r1), float(g1), float(b1))'
c2 = '(float(r2), float(g2), float(b2))'
bands = ImageMath.eval('set_lum({}, lum({}))'.format(c1, c2),
set_lum=set_lum,
lum=lum,
r1=r1,
g1=g1,
b1=b1,
r2=r2,
b2=b2,
g2=g2)
expected1 = [
[pytest.approx(41.13881001122631, 1e-6)],
[pytest.approx(148.48874067225782, 1e-6)],
[255],
]
assert [list(band.im.getdata()) for band in bands] == expected1
im_set_lum = Image.merge('RGB', [_convert(band, 'L').im for band in bands])
expected2 = [(floor(41.13881001122631), floor(148.48874067225782), 255)]
assert list(im_set_lum.getdata()) == expected2
def _soft_light(cb, cs, d_cb):
"""Returns ImageMath operands for soft light"""
cb = _float(cb) / 255
cs = _float(cs) / 255
d_cb = _float(d_cb) / 255
c1 = (cs <= .5) * (cb - (1 - 2 * cs) * cb * (1 - cb))
c2 = (cs > .5) * (cb + (2 * cs - 1) * d_cb)
return _convert((c1 + c2) * 255, 'L')
def _color(im1, im2):
"""The color blend mode.
Arguments:
im1: A backdrop image (RGB).
im2: A source image (RGB).
Returns:
The output image.
"""
r, g, b = im2.split() # Cs
lum_cb = lum_im(im1) # Lum(Cb)
lum_cs = lum_im(im2) # Lum(C) in SetLum
bands = ImageMath.eval(
'f((r, g, b), lum_cb, lum_cs)',
f=_color_image_math, r=r, g=g, b=b, lum_cb=lum_cb, lum_cs=lum_cs)
bands = [_convert(band, 'L').im for band in bands]
return Image.merge('RGB', bands)
def _hue(im1, im2):
"""The hue blend mode.
Arguments:
im1: A backdrop image (RGB).
im2: A source image (RGB).
Returns:
The output image.
"""
r1, g1, b1 = im1.split() # Cb
r2, g2, b2 = im2.split() # Cs
lum_cb = lum_im(im1) # Lum(Cb)
bands = ImageMath.eval(
'f((r1, g1, b1), (r2, g2, b2), lum_cb)', f=_hue_image_math,
r1=r1, g1=g1, b1=b1, r2=r2, g2=g2, b2=b2, lum_cb=lum_cb)
bands = [_convert(band, 'L').im for band in bands]
return Image.merge('RGB', bands)
def _color_dodge(cb, cs_inv):
cb = _float(cb)
cs_inv = _float(cs_inv)
cm = ((cb != 0) * (cs_inv == 0) + (cb / cs_inv)) * 255
return _convert(cm, 'L')
def _color_burn(cb, cs):
cm = (cb == 255) * 255 + \
(cb < 255) * (cs > 0) * (255 - ((255 - cb) * 255 / cs))
return _convert(cm, 'L')
def _color_burn_image_math(cb, cs):
"""Returns ImageMath operands for color burn blend mode"""
cm = (cb == 255) * 255 + \
(cb < 255) * (cs > 0) * (255 - ((255 - cb) * 255 / cs))
return _convert(cm, 'L')