How to check the libjpeg-turbo is built into opencv?

Question

I download the opencv3.4.5 from github https://github.com/opencv/opencv/archive/3.4.5.zip. And the libjpeg-turbo is located at 3rdparty dir. And build it with -D WITH_JPEG=ON and -D BUILD_JPEG=ON added. I can check this in CMakeCache.txt. But i cannot find any thing related with libjpeg-turbo at install/include or install/lib. How to test and verify the libjpeg-turbo is built into opencv? Instead of system libjpeg.

Answer 1

There should be a binary (executable) in your package called opencv_version, which you can run like this:

opencv_version -v | grep -i jpeg

Sample Output

JPEG:                        build-libjpeg-turbo (ver 1.5.3-62)
JPEG 2000:                   build (ver 1.900.1)

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Equally, within Python, you can do:

import cv2
print(cv2.getBuildInformation())

Or, maybe more succinctly:

import cv2
import re                                                                                   

re.findall('.*jpeg.*',cv2.getBuildInformation())                               

Sample Output:

['    JPEG:                        build-libjpeg-turbo (ver 1.5.3-62)']