@native-api Thanks so much for this, but we need some additional changes as you remove libjpeg-turbo too.

No need for changes. The build logic will detect that relevant envvars are no longer present and use the one bundled with OpenCV.
You can delete the corresponding logic from setup.py altogether if you'd like to but it's not strictly necessary atm.

I deleted libjpeg-turbo from dockerfile because it was failing the build, see commit message.

@native-api Change this part here from setup.py which redirects OpenCV to use custom jpeg libs:

if all(v in os.environ for v in ('JPEG_INCLUDE_DIR', 'JPEG_LIBRARY')):
            cmake_args += [
                "-DBUILD_JPEG=OFF",
                "-DJPEG_INCLUDE_DIR=%s" % os.environ['JPEG_INCLUDE_DIR'],
                "-DJPEG_LIBRARY=%s" % os.environ['JPEG_LIBRARY']
            ]

to

 cmake_args += ["-DBUILD_JPEG=ON"]

Or simply just remove it entirely, as "-DBUILD_JPEG=ON" is set by default in OpenCV cmake .

@native-api This change is very important as build will fail if no jpeg libs are found.

if all(v in os.environ for v in ('JPEG_INCLUDE_DIR', 'JPEG_LIBRARY')):

this ensures that a custom JPEG library is only used if JPEG_INCLUDE_DIR and JPEG_LIBRARY envvars are present.

As it is now, the bundled jpeg-turbo is already used, I checked:

--   Media I/O: 
--     ZLib:                        /lib/libz.so (ver 1.2.3)
--     JPEG:                        libjpeg-turbo (ver 2.0.2-62)
<...>
[  4%] Built target libtiff
[  9%] Built target libjpeg-turbo
[  5%] Built target libpng
<...>

If you can't understand why there's no problem due to #4 (comment) , just trust me on this.

@native-api ooh, I misread that comment. My apologies. I'll merge it.