我正在尝试使用Python通过主成分分析(PCA)进行人脸识别。现在,我能够获得训练图像“images”和输入图像“input_image”之间的最小欧几里得距离。以下是我的代码:
import os
from PIL import Image
import numpy as np
import glob
import numpy.linalg as linalg
#Step1: put database images into a 2D array
filenames = glob.glob('C:\\Users\\me\\Downloads\\/*.pgm')
filenames.sort()
img = [Image.open(fn).convert('L').resize((90, 90)) for fn in filenames]
images = np.asarray([np.array(im).flatten() for im in img])
#Step 2: find the mean image and the mean-shifted input images
mean_image = images.mean(axis=0)
shifted_images = images - mean_image
#Step 3: Covariance
c = np.asmatrix(shifted_images) * np.asmatrix(shifted_images.T)
#Step 4: Sorted eigenvalues and eigenvectors
eigenvalues,eigenvectors = linalg.eig(c)
idx = np.argsort(-eigenvalues)
eigenvalues = eigenvalues[idx]
eigenvectors = eigenvectors[:, idx]
#Step 5: Only keep the top 'num_eigenfaces' eigenvectors
num_components = 20
eigenvalues = eigenvalues[0:num_components].copy()
eigenvectors = eigenvectors[:, 0:num_components].copy()
#Step 6: Finding weights
w = eigenvectors.T * np.asmatrix(shifted_images)
# check eigenvectors.T/eigenvectors
#Step 7: Input image
input_image = Image.open('C:\\Users\\me\\Test\\5.pgm').convert('L').resize((90, 90))
input_image = np.asarray(input_image).flatten()
#Step 8: get the normalized image, covariance,
# eigenvalues and eigenvectors for input image
shifted_in = input_image - mean_image
c = np.cov(input_image)
cmat = c.reshape(1,1)
eigenvalues_in, eigenvectors_in = linalg.eig(cmat)
#Step 9: Find weights of input image
w_in = eigenvectors_in.T * np.asmatrix(shifted_in)
# check eigenvectors/eigenvectors_in
#Step 10: Euclidean distance
d = np.sqrt(np.sum(np.asarray(w - w_in)**2, axis=1))
idx = np.argmin(d)
print idx
我的问题是,我想返回与最小欧几里得距离相对应的图像(或其在数组images
中的索引),而不是它在距离数组d
中的索引。
images
包含30张图片(3个人脸,每个人10张)。而d
由20个距离组成,所以idx
的最大值为20,因此如果测试图片input_images
包含第3张图片(输出应该在21-30之间),我永远无法得到正确的结果。 - user2229953