Ubuntu 20.04 报错记录: Matplotlib 无法使用 OpenCV 的 libqxcb.so

news2025/5/19 18:15:17

网上查了一下这个报错，有很多解决方案，但是都不是针对 OpenCV 触发的这种

qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in " */lib/*/site-packages/cv2/qt/plugins" even though it was found.

本文的方案是牺牲 cv2.imshow，修复 plt.imshow，省流直接看 Test 3

未找到根治的解决方案，欢迎大家讨论

测试及分析

测试环境如下

Conda: Miniconda3-py313_25.3.1-1-Linux-x86_64.sh

Python: 3.10.16

OpenCV: 4.11.0
NumPy: 1.26.4
Matplotlib: 3.10.3

Test 1

import cv2
import matplotlib.pyplot as plt
import numpy as np

img = np.random.random([100, 199])

# OpenCV Visualization
cv2.imshow("win", img)
cv2.waitKey(0)

# Matplotlib Visualization
plt.imshow(img)
plt.show()

OpenCV 的可视化窗口可以正常显示；但关闭窗口后，后续代码无法运行

或者说，cv2.waitKey 卡死了后面的程序

Test 2

在 Test 1 基础上，将 cv2.waitKey 注释

import cv2
import matplotlib.pyplot as plt
import numpy as np

img = np.random.random([100, 199])

# OpenCV Visualization
cv2.imshow("win", img)
# cv2.waitKey(0)

# Matplotlib Visualization
plt.imshow(img)
plt.show()

cv2.imshow 仍然可以显示，但因为没有 cv2.waitKey 窗口只是闪现了一下

除去报错中的无效信息，有助于排查错误的内容如下

qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in " */lib/*/site-packages/cv2/qt/plugins" even though it was found.

This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

找到目录 */lib/*/site-packages/cv2/qt/plugins，其中确实有一个叫做 libqxcb.so 的文件

所以问题在于，Matplotlib 无法使用 OpenCV 的 libqxcb.so

Test 3

在 Test 1 基础上，将 cv2 的相关代码注释

import cv2
import matplotlib.pyplot as plt
import numpy as np

img = np.random.random([100, 199])

# OpenCV Visualization
# cv2.imshow("win", img)
# cv2.waitKey(0)

# Matplotlib Visualization
plt.imshow(img)
plt.show()

在 /usr 目录下搜索 libqxcb.so，尝试替换 OpenCV 自带的 (即替换 */lib/*/site-packages/cv2/qt/plugins 下的 libqxcb.so)，回退的话直接重装 opencv-python 即可

直到 plt.show 可以正常显示，我用的是 /usr/local/cuda-12.8/nsight-systems-2024.6.2/host-linux-x64/Plugins/platforms/libqxcb.so

如果此时重新运行 Test 1 的代码，那么 cv2.imshow 会引发以下报错

qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "*/lib/*/site-packages/cv2/qt/plugins"
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.