making movie file

Hi All,

I am trying to make a movie file from a image stack. I am using the following sample code (given in MATLAB)

***********************************************************
imgstack = uint16(zeros(32,128,1,no_of_frames));
for frame = 1:no_of_frames
[imgstack(:,:,1,frame)] = imread(filename, frame);
end

map = (linspace(0,64,65))'; map = repmat(map,1,3)/64;
mov = immovie(imagestack,map);
movie2avi(mov,filename)
**********************************************

Few frames (in the middle) have increased intensity in one region. So I expect to see something like a light bulb go on and off. But I notice that it is too bright all over. I want to scale the frames such that max intensity pixel represents 1.0 in colormap and min intensity pixel represent zero (over all frames). In other words the same 'map' is applied universally to all pixels in all frames. How can I do that in the movie? One idea I had is to apply different maps to diff frames, but I dont know how to implement it.

please help

thanks

rishabh

Answer 1

[Walter Roberson]

Without answering your question, here are some efficiency hints:

imgstack = zeros(32,128,1,no_of_frames, 'uint16');

map = ndgrid(0:1/64:1,[0 0 0]);

Specifying a frame number to imread() in the way you have is supported only for .CUR and .GIF files. If you are using .GIF files (but not .CUR files) then you could probably gain a fair bit of efficiency by reading all of the frames in a single call, by specifying 1:nframes as the index. .CUR files only support reading one frame at a time. The only other file type that supports reading frames is TIFF files, for which you must use

imread(filename, 'Index', frame)

and a vector of frames is not permitted for TIFF.