仅批处理 reading/saving 个文件夹中的最后一张图像

Question

我正在尝试将批处理添加到我正在制作的 OpenCV python 脚本中，但我终究无法看到我做错了什么。我是这方面的初学者，所以它可能有些愚蠢。最后，我希望脚本读取脚本当前工作目录中的每个图像文件，然后根据来自 openCV 的人脸检测进行裁剪，并将裁剪后的同名图像输出到 CWD 内的文件夹中。现在它所做的只是将文件夹中的最后一张图像输出到输出文件夹中。知道自己在做什么的人有什么想法吗？

import cv2
import sys
import os.path
import glob

#Cascade path
cascPath = 'haarcascade_frontalface_default.xml'

# Create the haar cascade
faceCascade = cv2.CascadeClassifier(cascPath)

# Read Images
images = glob.glob('*.jpg')
for i in images:
    image = cv2.imread(i,1)

#Convert to grayscale
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

# Find face(s) using cascade
faces = faceCascade.detectMultiScale(
    gray,
    scaleFactor=1.1, #size of groups
    minNeighbors=5, #How many groups around are detected as face for it to be valid
    minSize=(300, 300) #Min size in pixels for face
)

# Outputs number of faces found in image
print('Found {0} faces!'.format(len(faces)))

# Places a rectangle on face (For debugging, wont be in crop version)
for (x, y, w, h) in faces:
    cv2.rectangle(image, (x, y), (x+w, y+h), (255, 255, 255), 4)

# Resizes image to fit monitor and displayes it
imOut = cv2.resize(image, (750, 1142))
#cv2.imshow("Faces found", imS)
#cv2.waitKey(0)

#Saves image to output folder and creates folder if it doesnt exist
if not os.path.exists('output'):
    os.makedirs('output')
os.chdir('output')
cv2.imwrite(i, imOut)

Answer 1

images = glob.glob('*.jpg')
for i in images:
    image = cv2.imread(i,1)

#Convert to grayscale
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
...

您正在做的是：一张一张地打开每张图片，当您到达最后一张图片时，对最后一张图片应用操作。

如果您只在第一个 for 循环下包含要应用于一张图像的所有操作，则可以轻松解决此问题。注意缩进，这基本上就是你在这里做错的地方。

images = glob.glob('*.jpg')
for i in images:
    image = cv2.imread(i,1)

    #Convert to grayscale
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    
    #do all your operations here

Answer 2

我在代码中进行了多次更正

1. 您需要给出 haarcascade_frontalface_default.xml
例如：在Unix系统中：
```
cascPath = 'opencv/data/haarcascades/haarcascade_frontalface_default.xml'
```
1. 您不应在循环期间创建目录。您应该在循环之前创建它。
```
if not os.path.exists('output'):
  os.makedirs('output')
```
1. 您不需要更改目录来保存图像。只需在图片前添加路径即可。
```
img_name = "output/out_{}.png".format(c) # c is the counter  
```
1. 缩进很重要，否则，您可能会遇到困难。

示例代码：

import cv2
import os.path
import glob

# Cascade path
cascPath = '/opencv/data/haarcascades/haarcascade_frontalface_default.xml'

# Create the haar cascade
faceCascade = cv2.CascadeClassifier(cascPath)

if not os.path.exists('output'):
    os.makedirs('output')

# Read Images
images = glob.glob('images/*.jpg')
for c, i in enumerate(images):
    image = cv2.imread(i, 1)

    # Convert to grayscale
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

    # Find face(s) using cascade
    faces = faceCascade.detectMultiScale(
        gray,
        scaleFactor=1.1,  # size of groups
        minNeighbors=5,  # How many groups around are detected as face for it to be valid
        minSize=(300, 300)  # Min size in pixels for face
    )

    # Outputs number of faces found in image
    print('Found {0} faces!'.format(len(faces)))

    # Places a rectangle on face (For debugging, wont be in crop version)
    for (x, y, w, h) in faces:
        cv2.rectangle(image, (x, y), (x + w, y + h), (255, 255, 255), 4)

    if len(faces) > 0:
        # Resizes image to fit monitor and displayes it
        imOut = cv2.resize(image, (750, 1142))
        # cv2.imshow("Faces found", imS)
        # cv2.waitKey(0)

        # Saves image to output folder and creates folder if it doesnt exist

        # os.chdir('output')
        img_name = "output/out_{}.png".format(c)
        cv2.imwrite(img_name, imOut)

示例输出：

仅批处理 reading/saving 个文件夹中的最后一张图像

Batching only reading/saving last image in folder

opencv

photo

batching

python-3.x