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社区首页 >问答首页 >在google Colab中使用cv2.imshow()

在google Colab中使用cv2.imshow()
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Stack Overflow用户
提问于 2019-07-18 16:52:08
回答 3查看 23.3K关注 0票数 5

我正在尝试通过输入视频来对视频进行对象检测

cap = cv2.VideoCapture("video3.mp4")

并且在处理部分之后,我想显示具有实时对象检测的视频

代码语言:javascript
运行
复制
while True:
ret, image_np = cap.read()

# Expand dimensions since the model expects images to have shape: [1, None, None, 3]
image_np_expanded = np.expand_dims(image_np, axis=0)
# Actual detection.
output_dict = run_inference_for_single_image(image_np_expanded, detection_graph)
# Visualization of the results of a detection.
vis_util.visualize_boxes_and_labels_on_image_array(
    image_np,
    output_dict['detection_boxes'],
    output_dict['detection_classes'],
    output_dict['detection_scores'],
    category_index,
    instance_masks=output_dict.get('detection_masks'),
    use_normalized_coordinates=True,
    line_thickness=8)

cv2.imshow('object detection', cv2.resize(image_np, (800, 600)))
if cv2.waitKey(25) & 0XFF == ord('q'):
    cv2.destroyAllWindows()
    break

但colab表示cv2.imshow()被禁用,并使用cv2_imshow()。但它只渲染图像。一帧接一帧。我想像使用cv2.imshow()一样输出视频。请帮我解决这个问题。提前谢谢。

我的完整代码附在附件中

代码语言:javascript
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复制
import numpy as np
import os
import six.moves.urllib as urllib
import sys
import tarfile
import tensorflow as tf
import zipfile

from distutils.version import StrictVersion
from collections import defaultdict
from io import StringIO
from matplotlib import pyplot as plt
from PIL import Image

import cv2
from google.colab.patches import cv2_imshow

cap = cv2.VideoCapture("video3.mp4")

sys.path.append("..")
from object_detection.utils import ops as utils_ops

if StrictVersion(tf.__version__) < StrictVersion('1.12.0'):
raise ImportError('Please upgrade your TensorFlow installation to v1.12.*.')

from object_detection.utils import label_map_util

from object_detection.utils import visualization_utils as vis_util

detection_graph = tf.Graph()
with detection_graph.as_default():
od_graph_def = tf.GraphDef()
with tf.gfile.GFile(PATH_TO_FROZEN_GRAPH, 'rb') as fid:
serialized_graph = fid.read()
od_graph_def.ParseFromString(serialized_graph)
tf.import_graph_def(od_graph_def, name='')


category_index = label_map_util.create_category_index_from_labelmap(PATH_TO_LABELS, use_display_name=True)


def load_image_into_numpy_array(image):
(im_width, im_height) = image.size
return np.array(image.getdata()).reshape(
  (im_height, im_width, 3)).astype(np.uint8)


PATH_TO_TEST_IMAGES_DIR = 'test_images'
TEST_IMAGE_PATHS = [ os.path.join(PATH_TO_TEST_IMAGES_DIR, 'image{}.jpg'.format(i)) for i in range(3, 8) ]

IMAGE_SIZE = (12, 8)

def run_inference_for_single_image(image, graph):
with graph.as_default():
with tf.Session() as sess:

  ops = tf.get_default_graph().get_operations()
  all_tensor_names = {output.name for op in ops for output in op.outputs}
  tensor_dict = {}
  for key in [
      'num_detections', 'detection_boxes', 'detection_scores',
      'detection_classes', 'detection_masks'
  ]:
    tensor_name = key + ':0'
    if tensor_name in all_tensor_names:
      tensor_dict[key] = tf.get_default_graph().get_tensor_by_name(
          tensor_name)
  if 'detection_masks' in tensor_dict:

    detection_boxes = tf.squeeze(tensor_dict['detection_boxes'], [0])
    detection_masks = tf.squeeze(tensor_dict['detection_masks'], [0])

    real_num_detection = tf.cast(tensor_dict['num_detections'][0], tf.int32)
    detection_boxes = tf.slice(detection_boxes, [0, 0], [real_num_detection, -1])
    detection_masks = tf.slice(detection_masks, [0, 0, 0], [real_num_detection, -1, -1])
    detection_masks_reframed = utils_ops.reframe_box_masks_to_image_masks(
        detection_masks, detection_boxes, image.shape[1], image.shape[2])
    detection_masks_reframed = tf.cast(
        tf.greater(detection_masks_reframed, 0.5), tf.uint8)

    tensor_dict['detection_masks'] = tf.expand_dims(
        detection_masks_reframed, 0)
  image_tensor = tf.get_default_graph().get_tensor_by_name('image_tensor:0')


  output_dict = sess.run(tensor_dict,
                         feed_dict={image_tensor: image})


  output_dict['num_detections'] = int(output_dict['num_detections'][0])
  output_dict['detection_classes'] = output_dict[
      'detection_classes'][0].astype(np.int64)
  output_dict['detection_boxes'] = output_dict['detection_boxes'][0]
  output_dict['detection_scores'] = output_dict['detection_scores'][0]
  if 'detection_masks' in output_dict:
    output_dict['detection_masks'] = output_dict['detection_masks'][0]
return output_dict

while True:
    ret, image_np = cap.read()

    image_np_expanded = np.expand_dims(image_np, axis=0)

    output_dict = run_inference_for_single_image(image_np_expanded, detection_graph)

    vis_util.visualize_boxes_and_labels_on_image_array(
    image_np,
    output_dict['detection_boxes'],
    output_dict['detection_classes'],
    output_dict['detection_scores'],
    category_index,
    instance_masks=output_dict.get('detection_masks'),
    use_normalized_coordinates=True,
    line_thickness=8)

cv2_imshow(image_np)
if cv2.waitKey(25) & 0XFF == ord('q'):
    cv2.destroyAllWindows()
    break
EN

回答 3

Stack Overflow用户

发布于 2020-03-09 07:49:05

要在google colab中使用cv2.imshow,您可以使用以下导入:

代码语言:javascript
运行
复制
from google.colab.patches import cv2_imshow
cv2_imshow(img)
票数 10
EN

Stack Overflow用户

发布于 2019-07-18 17:33:42

This Colab notebook提供了一种在笔记本上查看视频的方法:

代码语言:javascript
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import io
import base64
from IPython.display import HTML

def playvideo(filename):
    video = io.open(filename, 'r+b').read()
    encoded = base64.b64encode(video)
    return HTML(data='''<video alt="test" controls>
                    <source src="data:video/mp4;base64,{0}" type="video/mp4"/>
                 </video>'''.format(encoded.decode('ascii')))

然后使用playvideo('./Megamind.mp4')观看视频。

无论如何,记得把%pylab notebook放在笔记本的开头,这在很大程度上有助于解决这类问题。

票数 2
EN

Stack Overflow用户

发布于 2020-12-02 11:50:45

展示如何在Colab中处理视频的示例:#定义辅助函数以显示视频从IPython.display导入io从base64导入HTML导入b64encode def show_video(file_name,width=640):

代码语言:javascript
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  mp4 = open(file_name,'rb').read()
  data_url = "data:video/mp4;base64," + b64encode(mp4).decode()
  return HTML("""
  <video width="{0}" controls>
        <source src="{1}" type="video/mp4">
  </video>
  """.format(width, data_url))
#convert resulting video from avi to mp4 file format
import os
path_video = os.path.join("outputs","tracker.avi")
%cd outputs/
!ffmpeg -y -loglevel panic -i tracker.avi output.mp4
%cd ..

#output object tracking video
path_output = os.path.join("outputs","output.mp4")
show_video(path_output, width=960)
票数 0
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接:

https://stackoverflow.com/questions/57090598

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