Transfer SIFT to the main repository

[ychechik]

As of the day after tomorrow (7.3.20) the patent on SIFT will expire and so it should be free to use.

Moving it out of the non-free folder will enable all to compile opencv with default flags and still get SIFT (will also help for the python binding as it doesn't compile the non-free folder).

[vpisarev]

See https://github.com/opencv/opencv/wiki/GSoC_2020#idea-better-sift-in-the-main-repository

[alalek]

As a quick step in this way we can remove #ifdef guards with OPENCV_ENABLE_NONFREE for SIFT source code in opencv_contrib repository (without moving the code).

[saskatchewancatch]

@alalek @vpisarev , I attempted this in PR 2449 in opencv_contrib repository. It implements the "quick step" by moving SIFT out of non-free into free. I suppose the rest of the work involving moving it into opencv could be a later work for GSoC as per Vadim's suggestion.

[flokixdev]

Can I ask, when we can expect it to be included in a new release?
Thank you!

[alalek]

#17119 backlog:

• 2 disabled SIFT tests
• fix C++ compatibility? cv::xfeatures2d::SIFT::create() (problem is due MSVS ambiguous errors)
• fix Java bindings compatibility? org.opencv.features2d.SIFT.create()

[Austral-IV]

If SIFT is now included in the packages, why do i get a module 'cv2.cv2' has no attribute 'xfeatures2d' error when using the opencv-python pip package and a DEPRACATED error when trying with the opencv-contrib-python package? which should I use?

[towr]

@Zenos-Paradox
It looks like it's been moved. You should use cv2.SIFT_create() instead of cv2.xfeatures2d.SIFT_create() now. (xfeatures2d only exists in the contrib package, but sift is part of the main package now.)

[Austral-IV]

Oh, alright. Thanks. El mar, 1 jun 2021 a las 8:33, towr ***@***.***>) escribió:

…

@Zenos-Paradox <https://github.com/Zenos-Paradox> It looks like it's been moved. You should use cv2.SIFT_create() instead of cv2.xfeatures2d.SIFT_create() now. (xfeatures2d only exists in the contrib package, but sift is part of the main package now.) — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#16736 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AQTMGLPPP7C2WJ4SIFDZ2KTTQTHRJANCNFSM4LCGEMTA> .

[HaiderAbasi]

For anyone still stuck...

SIFT was not working for me in OpenCV-contib-python (Version 4.2.0.34) either.
Both of methods cv2.xfeatures2d.SIFT_create() and cv2.SIFT_create() Did not work!

What did work:
pip install opencv-contrib-python==4.4.0.46

OS = Windows 10
Python Version = 3.8.10

[Byte247]

@HaiderAbasi what exactly did you do after installing opencv-contrib-python==4.4.0.46? Did you still use cv2.xfeatures2d.SIFT_create() or cv2.SIFT_create() ?

[danielagam]

@HaiderAbasi what exactly did you do after installing opencv-contrib-python==4.4.0.46? Did you still use cv2.xfeatures2d.SIFT_create() or cv2.SIFT_create() ?

cv2.xfeatures2d.SIFT_create() show warning so I use cv2.SIFT_create() and the warning disappeared.