def lum_eq(self):
# RGB/YUV color conversion
self._ref_img = misc.yuv_conv(self._ref_img)
# create cumulative distribution function of reference image
self.set_histeq_params()
# histogram mapping using cumulative distribution function
self.correct_histeq()
# YUV/RGB color conversion
return misc.yuv_conv(self._ref_img, inverse=True)
def apply_stretch_lum(self):
''' contrast and brightness rectification to luminance channel of provided RGB image '''
# color model conversion
self.vp_img_arr = misc.yuv_conv(self.vp_img_arr) if len(
self.vp_img_arr.shape) > 4 else self.vp_img_arr
# apply histogram stretching to luminance channel only
self.apply_stretch(ch=0)
# color model conversion
self.vp_img_arr = misc.yuv_conv(self.vp_img_arr, inverse=True)
return True
def uv_eq(self):
# RGB/YUV color conversion
self._ref_img = misc.yuv_conv(self._ref_img)
for i in range(1, self._ref_img.shape[-1]):
# create cumulative distribution function of reference image
self.set_histeq_params(ch=i)
# histogram mapping using cumulative distribution function
self.correct_histeq(ch=i)
# YUV/RGB color conversion
return misc.yuv_conv(self._ref_img, inverse=True)
def correct_luma_outliers(self, img, n=2, perc=.2):
# luma channel conversion
luma = misc.yuv_conv(img.copy())[..., 0]
for j in range(n, luma.shape[0] - n):
for i in range(n, luma.shape[1] - n):
win = luma[j - n:j + n + 1, i - n:i + n + 1]
# hot pixel detection
num_hi = len(win[win > luma[j, i] * (1 - perc)])
# dead pixel detection
num_lo = len(win[win < luma[j, i] * (1 + perc)])
if num_hi < win.size / 5 or num_lo < win.size / 5:
# replace outlier by average of all directly adjacent pixels
img[j,
i, :] = (sum(sum(img[j - 1:j + 2, i - 1:i + 2, :])) -
img[j, i, :]) / 8.
# check interrupt status
if self.sta.interrupt:
return False
return img
def fit_patch(self, patch, th=None):
self._th = th if th is not None else self._th
x = np.linspace(0, 1, patch.shape[1])
y = np.linspace(0, 1, patch.shape[0])
X, Y = np.meshgrid(x, y, copy=False)
X = X.flatten()
Y = Y.flatten()
b = misc.yuv_conv(patch)[..., 0].flatten()
A = self.compose_vandermonde(X, Y, deg=3)
# Solve for a least squares estimate via pseudo inverse and coefficients in beta
coeffs = np.dot(np.linalg.pinv(A), b)
# create weighting window
weight_win = np.dot(A, coeffs).reshape(patch.shape[1], patch.shape[0])[..., np.newaxis]
weight_win /= weight_win.max()
# thresholding (to prevent too large numbers in corrected image)
weight_win[weight_win < self._th] = self._th
return coeffs, weight_win
def correct_luma_outliers(img, n=2, perc=.2, sta=None):
# status init
sta = sta if sta is not None else misc.PlenopticamStatus()
sta.status_msg('Hot pixel removal', True)
# luma channel conversion
luma = misc.yuv_conv(img.copy())[..., 0]
for i in range(n, luma.shape[0] - n):
for j in range(n, luma.shape[1] - n):
win = luma[i - n:i + n + 1, j - n:j + n + 1]
# hot pixel detection
num_hi = len(win[win > luma[i, j] * (1 - perc)])
# dead pixel detection
num_lo = len(win[win < luma[i, j] * (1 + perc)])
if num_hi < win.size / 5 or num_lo < win.size / 5:
# replace outlier by average of all directly adjacent pixels
img[i, j, :] = (sum(sum(img[i - 1:i + 2, j - 1:j + 2, :])) -
img[i, j, :]) / 8.
# progress update
sta.progress((i * luma.shape[1] + (j + 1)) / luma.size * 100, True)
return img
def michelson_contrast(img_tile):
''' https://colorusage.arc.nasa.gov/luminance_cont.php '''
lum_tile = misc.yuv_conv(img_tile)[..., 0]
c_m = (lum_tile.max() - lum_tile.min()) / (lum_tile.max() + lum_tile.min())
return c_m
def correct_contrast(img_arr, contrast=1, brightness=0, ch=0):
# color model conversion
img_yuv = misc.yuv_conv(img_arr)
# convert to float
f = img_yuv[..., ch].astype(np.float32)
# perform auto contrast (by default: "value" channel only)
img_yuv[..., ch] = contrast * f + brightness
# clip to input extrema to remove contrast outliers
img_yuv[..., ch][img_yuv[..., ch] < img_arr.min()] = img_arr.min()
img_yuv[..., ch][img_yuv[..., ch] > img_arr.max()] = img_arr.max()
# color model conversion
img = misc.yuv_conv(img_yuv, inverse=True)
return img
def con_bal(self):
# estimate contrast and brightness via least-squares method
self.set_stretch(ref_ch=misc.yuv_conv(self.central_view)[..., 0])
self.proc_vp_arr(misc.yuv_conv)
self.proc_vp_arr(self.apply_stretch, ch=0, msg='Contrast balance')
self.proc_vp_arr(misc.yuv_conv, inverse=True)
# status update
self.sta.progress(100, opt=self.cfg.params[self.cfg.opt_prnt])
def robust_awb(img, t=0.3, max_iter=1000):
''' inspired by Jun-yan Huo et al. and http://web.stanford.edu/~sujason/ColorBalancing/Code/robustAWB.m '''
img = misc.type_norm(img, dtype='float16', lim_min=0, lim_max=1.0)
ref_pixel = img[0, 0, :].copy()
u = .01 # gain step size
a = .8 # double step threshold
b = .001 # convergence threshold
gains_adj = np.array([1., 1., 1.])
#sRGBtoXYZ = [[0.4124564, 0.3575761, 0.1804375], [0.2126729, 0.7151522, 0.0721750], [0.0193339, 0.1191920, 0.9503041]]
sRGBtoXYZ = [[0.4124564, 0.2126729, 0.0193339],
[0.3575761, 0.7151522, 0.0193339],
[0.1804375, 0.0721750, 0.9503041]]
for i in range(max_iter):
img_yuv = misc.yuv_conv(img)
f = (abs(img_yuv[..., 1]) + abs(img_yuv[..., 2])) / img_yuv[..., 0]
grays = np.zeros(img_yuv.shape)
grays[f < t] = img_yuv[f < t]
if np.sum(f < t) == 0:
print('No valid gray pixels found.')
break
u_bar = np.mean(grays[..., 1]) #estimate
v_bar = np.mean(grays[..., 2]) #estimate
#rgb_est = misc.yuv_conv(np.array([100, u_bar, v_bar]), inverse=True) # convert average gray from YUV to RGB
# U > V: blue needs adjustment otherwise red is treated
err, ch = (u_bar, 2) if abs(u_bar) > abs(v_bar) else (v_bar, 0)
if abs(err) >= a:
delta = 2 * np.sign(
err) * u # accelerate gain adjustment if far off
elif abs(err) < b: #converged
delta = 0
print(('Converged. U_bar and V_bar < {0} in magnitude.').format(
str(b)))
break
else:
delta = err * u
gains_adj[ch] -= delta # negative fdbk loop
img = np.dot(img, np.diag(gains_adj))
gains = img[0, 0, :] / ref_pixel
return gains
def robust_awb(self, t=0.3, max_iter=1000):
''' inspired by Jun-yan Huo et al. and http://web.stanford.edu/~sujason/ColorBalancing/Code/robustAWB.m '''
img = Normalizer(self.central_view).type_norm(dtype='float16',
lim_min=0,
lim_max=1.0)
ref_pixel = img[0, 0, :].copy()
u = .01 # gain step size
a = .8 # double step threshold
b = .001 # convergence threshold
gains_adj = np.array([1., 1., 1.])
for i in range(max_iter):
img_yuv = misc.yuv_conv(img)
f = (abs(img_yuv[..., 1]) + abs(img_yuv[..., 2])) / img_yuv[..., 0]
grays = np.zeros(img_yuv.shape)
grays[f < t] = img_yuv[f < t]
if np.sum(f < t) == 0:
self.sta.status_msg('No valid gray pixels found.',
self.cfg.params[self.cfg.opt_prnt])
break
u_bar = np.mean(grays[..., 1]) # estimate
v_bar = np.mean(grays[..., 2]) # estimate
# rgb_est = misc.yuv_conv(np.array([100, u_bar, v_bar]), inverse=True) # convert average gray from YUV to RGB
# U > V: blue needs adjustment otherwise red is treated
err, ch = (u_bar, 2) if abs(u_bar) > abs(v_bar) else (v_bar, 0)
if abs(err) >= a:
delta = 2 * np.sign(
err) * u # accelerate gain adjustment if far off
elif abs(err) < b: # converged when u_bar and v_bar < b
# delta = 0
#self.sta.status_msg('AWB convergence reached', self.cfg.params[self.cfg.opt_prnt])
break
else:
delta = err * u
# negative feedback loop
gains_adj[ch] -= delta
img = np.dot(img, np.diag(gains_adj))
# take gains only if result is obtained by convergence
if i != max_iter - 1:
self._gains = img[0, 0, :] / ref_pixel
return True
def auto_contrast(img_arr, p_lo=0.001, p_hi=0.999, ch=0):
''' according to Adi Shavit on https://stackoverflow.com/questions/9744255/instagram-lux-effect/9761841#9761841 '''
# estimate contrast und brightness parameters (by default: achromatic "luma" channel only)
val_lim = 2**16 - 1
img_yuv = misc.yuv_conv(img_arr)
h = np.histogram(img_yuv[..., ch], bins=np.arange(val_lim))[0]
H = np.cumsum(h) / float(np.sum(h))
try:
px_lo = find_x_given_y(p_lo, np.arange(val_lim), H)
px_hi = find_x_given_y(p_hi, np.arange(val_lim), H)
except:
px_lo = 0
px_hi = 1
A = np.array([[px_lo, 1], [px_hi, 1]])
b = np.array([0, val_lim])
contrast, brightness = np.dot(np.linalg.inv(A), b)
return contrast, brightness
def set_stretch_lum(self):
# use luminance channel for parameter analysis
ref_img = misc.yuv_conv(self.central_view)
self.set_stretch(ref_ch=ref_img[..., 0])