message: updated documentation for imread and imwrite (added pfm image format)
diff: @@ -145,6 +145,7 @@ Currently, the following file formats are supported:
  - Portable Network Graphics - \*.png (see the *Note* section)
  - WebP - \*.webp (see the *Note* section)
  - Portable image format - \*.pbm, \*.pgm, \*.ppm \*.pxm, \*.pnm (always supported)
  +- PFM files - \*.pfm (see the *Note* section)
  - Sun rasters - \*.sr, \*.ras (always supported)
  - TIFF files - \*.tiff, \*.tif (see the *Note* section)
  - OpenEXR Image files - \*.exr (see the *Note* section)
  @@ -171,6 +172,7 @@ Currently, the following file formats are supported:
  [Vector](http://www.gdal.org/ogr_formats.html).
  - If EXIF information are embedded in the image file, the EXIF orientation will be taken into account
  and thus the image will be rotated accordingly except if the flag @ref IMREAD_IGNORE_ORIENTATION is passed.
  +- Use the IMREAD_UNCHANGED flag to keep the floating point values from PFM image.
  @param filename Name of file to be loaded.
  @param flags Flag that can take values of cv::ImreadModes
  @@ -195,8 +197,9 @@ single-channel or 3-channel (with 'BGR' channel order) images
  can be saved using this function, with these exceptions:
  - 16-bit unsigned (CV_16U) images can be saved in the case of PNG, JPEG 2000, and TIFF formats
  -- 32-bit float (CV_32F) images can be saved in TIFF, OpenEXR, and Radiance HDR formats; 3-channel
  -(CV_32FC3) TIFF images will be saved using the LogLuv high dynamic range encoding (4 bytes per pixel)
  +- 32-bit float (CV_32F) images can be saved in PFM, TIFF, OpenEXR, and Radiance HDR formats;
  + 3-channel (CV_32FC3) TIFF images will be saved using the LogLuv high dynamic range encoding
  + (4 bytes per pixel)
  - PNG images with an alpha channel can be saved using this function. To do this, create
  8-bit (or 16-bit) 4-channel image BGRA, where the alpha channel goes last. Fully transparent pixels
  should have alpha set to 0, fully opaque pixels should have alpha set to 255/65535 (see the code sample below).
  