Image - an image processing library based upon Vix

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Motivated by the discussion on extracting frames from video, newly published Image version 0.22 supports some basic capabilities based upon the excellent Evision.VideoCapture module.

Enhancements

  • Adds Image.Video.image_from_video/2 to extract images from frames in a video file or video camera. Includes support for :frame and :millisecond seek options. Seek options are only supported for video files, not video streams.

  • Adds Image.Video.stream!/2 that returns an enumerable stream of frames as images. The stream takes a range as a parameter. For example:

  • Adds Image.Video.scrub/2 that scrubs the video head forward a number of frames.

  • Adds Image.Video.seek/2 to seek the video head to the requested frame or millisecond. Seeking is supported for video files only, not video streams. Seeking is not guaranteed to be frame accurate (due to underlying OpenCV issues).

Examples

# Extracting an image
iex> {:ok, video} = Image.Video.open "./test/support/video/video_sample.mp4"
iex> {:ok, _image} = Image.Video.image_from_video(video)
iex> {:ok, _image} = Image.Video.image_from_video(video, frame: 0)
iex> {:ok, _image} = Image.Video.image_from_video(video, millisecond: 1_000)

# Streaming images
# Extract every second frame starting at the
# first frame and ending at the last frame.
iex> "./test/support/video/video_sample.mp4"
...> |> Image.Video.stream!(frame: 0..-1//2)
...> |> Enum.to_list()
[
  %Vix.Vips.Image{ref: #Reference<0.2048151986.449445916.177398>},
  %Vix.Vips.Image{ref: #Reference<0.2048151986.449445916.177400>},
  %Vix.Vips.Image{ref: #Reference<0.2048151986.449445916.177402>},
  ...
]
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