Python OpenCV 中的陰影去除

Question

我正在嘗試使用 Finlayson 等的熵最小化方法在 python OpenCV 中實現陰影去除。 人：

“熵最小化的內在圖像”，Finlayson 等。 人。

我似乎無法匹配論文中的結果。 我的熵圖與論文中的不匹配，並且我得到了錯誤的最小熵。

有什么想法嗎？ （根據要求，我有更多的源代碼和論文）

#############
# LIBRARIES
#############
import numpy as np
import cv2
import os
import sys
import matplotlib.image as mpimg
import matplotlib.pyplot as plt
from PIL import Image
import scipy
from scipy.optimize import leastsq
from scipy.stats.mstats import gmean
from scipy.signal import argrelextrema
from scipy.stats import entropy
from scipy.signal import savgol_filter

root = r'\path\to\my_folder'
fl = r'my_file.jpg'

#############
# PROGRAM
#############
if __name__ == '__main__':

    #-----------------------------------
    ## 1. Create Chromaticity Vectors ##
    #-----------------------------------

    # Get Image
    img = cv2.imread(os.path.join(root, fl))
    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    h, w = img.shape[:2]

    plt.imshow(img)
    plt.title('Original')
    plt.show()

    img = cv2.GaussianBlur(img, (5,5), 0)

    # Separate Channels
    r, g, b = cv2.split(img) 

    im_sum = np.sum(img, axis=2)
    im_mean = gmean(img, axis=2)

    # Create "normalized", mean, and rg chromaticity vectors
    #  We use mean (works better than norm). rg Chromaticity is
    #  for visualization
    n_r = np.ma.divide( 1.*r, g )
    n_b = np.ma.divide( 1.*b, g )

    mean_r = np.ma.divide(1.*r, im_mean)
    mean_g = np.ma.divide(1.*g, im_mean)
    mean_b = np.ma.divide(1.*b, im_mean)

    rg_chrom_r = np.ma.divide(1.*r, im_sum)
    rg_chrom_g = np.ma.divide(1.*g, im_sum)
    rg_chrom_b = np.ma.divide(1.*b, im_sum)

    # Visualize rg Chromaticity --> DEBUGGING
    rg_chrom = np.zeros_like(img)

    rg_chrom[:,:,0] = np.clip(np.uint8(rg_chrom_r*255), 0, 255)
    rg_chrom[:,:,1] = np.clip(np.uint8(rg_chrom_g*255), 0, 255)
    rg_chrom[:,:,2] = np.clip(np.uint8(rg_chrom_b*255), 0, 255)

    plt.imshow(rg_chrom)
    plt.title('rg Chromaticity')
    plt.show()

    #-----------------------
    ## 2. Take Logarithms ##
    #-----------------------

    l_rg = np.ma.log(n_r)
    l_bg = np.ma.log(n_b)

    log_r = np.ma.log(mean_r)
    log_g = np.ma.log(mean_g)
    log_b = np.ma.log(mean_b)

    ##  rho = np.zeros_like(img, dtype=np.float64)
    ##
    ##  rho[:,:,0] = log_r
    ##  rho[:,:,1] = log_g
    ##  rho[:,:,2] = log_b

    rho = cv2.merge((log_r, log_g, log_b))

    # Visualize Logarithms --> DEBUGGING
    plt.scatter(l_rg, l_bg, s = 2)
    plt.xlabel('Log(R/G)')
    plt.ylabel('Log(B/G)')
    plt.title('Log Chromaticities')
    plt.show()

    plt.scatter(log_r, log_b, s = 2)
    plt.xlabel('Log( R / 3root(R*G*B) )')
    plt.ylabel('Log( B / 3root(R*G*B) )')
    plt.title('Geometric Mean Log Chromaticities')
    plt.show()

    #----------------------------
    ## 3. Rotate through Theta ##
    #----------------------------
    u = 1./np.sqrt(3)*np.array([[1,1,1]]).T
    I = np.eye(3)

    tol = 1e-15

    P_u_norm = I - u.dot(u.T)
    U_, s, V_ = np.linalg.svd(P_u_norm, full_matrices = False)

    s[ np.where( s <= tol ) ] = 0.

    U = np.dot(np.eye(3)*np.sqrt(s), V_)
    U = U[ ~np.all( U == 0, axis = 1) ].T

    # Columns are upside down and column 2 is negated...?
    U = U[::-1,:]
    U[:,1] *= -1.

    ##  TRUE ARRAY:
    ##
    ##  U = np.array([[ 0.70710678,  0.40824829],
    ##                [-0.70710678,  0.40824829],
    ##                [ 0.        , -0.81649658]])

    chi = rho.dot(U) 

    # Visualize chi --> DEBUGGING
    plt.scatter(chi[:,:,0], chi[:,:,1], s = 2)
    plt.xlabel('chi1')
    plt.ylabel('chi2')
    plt.title('2D Log Chromaticities')
    plt.show()

    e = np.array([[np.cos(np.radians(np.linspace(1, 180, 180))), \
                   np.sin(np.radians(np.linspace(1, 180, 180)))]])

    gs = chi.dot(e)

    prob = np.array([np.histogram(gs[...,i], bins='scott', density=True)[0] 
                      for i in range(np.size(gs, axis=3))])

    eta = np.array([entropy(p, base=2) for p in prob])

    plt.plot(eta)
    plt.xlabel('Angle (deg)')
    plt.ylabel('Entropy, eta')
    plt.title('Entropy Minimization')
    plt.show()

    theta_min = np.radians(np.argmin(eta))

    print('Min Angle: ', np.degrees(theta_min))

    e = np.array([[-1.*np.sin(theta_min)],
                  [np.cos(theta_min)]])

    gs_approx = chi.dot(e)

    # Visualize Grayscale Approximation --> DEBUGGING
    plt.imshow(gs_approx.squeeze(), cmap='gray')
    plt.title('Grayscale Approximation')
    plt.show()

    P_theta = np.ma.divide( np.dot(e, e.T), np.linalg.norm(e) )

    chi_theta = chi.dot(P_theta)
    rho_estim = chi_theta.dot(U.T)
    mean_estim = np.ma.exp(rho_estim)

    estim = np.zeros_like(mean_estim, dtype=np.float64)

    estim[:,:,0] = np.divide(mean_estim[:,:,0], np.sum(mean_estim, axis=2))
    estim[:,:,1] = np.divide(mean_estim[:,:,1], np.sum(mean_estim, axis=2))
    estim[:,:,2] = np.divide(mean_estim[:,:,2], np.sum(mean_estim, axis=2))

    plt.imshow(estim)
    plt.title('Invariant rg Chromaticity')
    plt.show()

輸出：

Answer 1

Shadow Removal Using Illumination Invariant Image Formation (Ranaweera, Drew)在結果和討論下指出，JPEG 圖像和 PNG 圖像的結果因 JPEG 壓縮而不同。 因此，期望結果與“熵最小化的內在圖像”（Finlayson 等人）顯示的完全一樣可能是不合理的。

我還注意到您沒有添加作者在其他論文中推薦的“額外光線”。

此外，在定義rg_chrom時，通道的順序需要是 BGR 而不是您使用的 RGB。

我正在努力實現這篇論文，所以你的代碼對我非常有用。 感謝那