How do I read in an AVI frame and save it to an image file in MATLAB?

I would like to process each frame of an AVI file separately. I would like to know how to access the individual frames, what image type I can save these frames in, and if I will have to save the AVI file as something different before I open it in MATLAB.

Answer 1

[MathWorks Support Team]

Accessing the individual AVI frames is not difficult and can be done in just a few short commands. As far as file types for the images, you can save in whatever file format that imwrite supports in your version of MATLAB.

Take for example an AVI-file called "clock.avi":

% READ THE AVI

mov=aviread('clock.avi');

% GRAB A SINGLE FRAME

[im1,map] = frame2im(mov(1));

% SHOW THE FRAME

imshow( im1 );

% SET THE COLORMAP PROPERLY SO THE IMAGE SHOWS CORRECTLY

colormap( map );

% WRITE OUT THE FRAME TO A BMP FILE

imwrite(im1,map,'clockFrame1.bmp');

For more details, see the documentation of the AVIREAD, FRAME2IM, IMSHOW, and IMWRITE functions used above.

[Eric]

As of R2014b, "aviread" should be changed to "VideoReader". Also, I believe the VideoReader object cannot be indexed to obtain a frame, but rather readFrame(vidObj) must be called. See MATLAB's examples on reading video files.