|| Richard Steffen on 2011-07-29 13:28
|| Priority: Low
|| Affected: None
|| Category: highgui-images
|| Tracker: Feature
|| Difficulty: 
|| PR: 
|| Platform: None / None

Currently, the imread and imwrite method only supports std::string as an input. This isn't working with non-ascii directories/paths. Therefore, the a software depends on OpenCV can not guaranty working on all maschines.

-   Description changed from Currently, the imread and imwrite method
    only supports std::string as an inpu... to Currently, the imread and
    imwrite method only supports std::string as an inpu... More

std::string is still capable of storing any unicode name via UTF-8 encoding, and so it's fopen responsibility to handle this UTF-8 name properly. On Mac and Linux I was able to store image into a file with non-ASCII letters using normal cv::imwrite(). I guess, on Windows it will work too, if you save a source file to UTF-8.
-   Priority changed from High to Low
-   Assignee set to Vadim Pisarevsky
-   Status changed from Open to Cancelled

-   Target version set to 2.4.0

AFAIK fopen does not support Unicode on Windows and can't be used to open a path with Unicode characters. The UTF-8 string must be converted to UTF-16 and given to _wfopen instead. See ImageMagick's fopen_utf8 wrapper for example code: http://www.imagemagick.org/api/MagickCore/utility-private_8h_source.html#l00103
-   Target version changed from 2.4.0 to 2.4.9
-   Status changed from Cancelled to Open

One possible workaround for now using Boost and a memory mapped file:

    mapped_file map(path(L"filename"), ios::in);
    Mat file(1, numeric_cast<int>(map.size()), CV_8S, const_cast<char*>(map.const_data()), CV_AUTOSTEP);
    Mat image(imdecode(file, 1));

The downside is that I/O errors cause access violations instead of C++ exceptions. Also don't write to the "file" Mat. :)

Unfortunately the trick of avoiding to store the image file in memory doesn't work with imwrite, as imencode stores the output in a vector with standard allocator specified. If memory is no issue the contents can of course be written to file using Boost afterwards.

-   Target version changed from 2.4.9 to 3.0