Used to apply the same operation to all images in given directory.
For each image in srcdir, loads the image, applies the function in fhandle and stores
the result. The result x=fhandle(I,params{:}) on the ith image is stored in
X(:,...:,i). If the size of x depends on the size of I, then all images in the
directory must have the same size. Also I may have a different format depending on how
it is stored on disk - example: MxN for grayscale, MxNx3 for RGB, MxNx4 for CMYK. This
function is very similar to feval_arrays, except instead of operating on images in
memory it operates on images on disk. For long operations shows progress information.
The srcdir must contain nothing but images. Either the images follow no naming
convention, or they follow a very rigid naming convention that consists of a string
followed by ndigits-number specifying the image number, followed by an extension. The
advantage of the more rigid naming convention is that it allows a certain range of
images to be operated on, specified by [nstart,nend]. For example, to operate on images
"rats0003.tif ... rats0113.tif" in directory '../rats/' use:
feval_images( fhandle, params, '../rats/', 'rats' , 'tif', 3, 113, 4 );
If the parameter name is specified ('rats' in the example above), the rigid naming
convention is assumed. All further input arguments are optional.
imwrite2 writes images in the format described above.
If the function in fhandle is identity (f=@(x) x), the result is to read in all images
in the directory.
A limitation of feval_images is that it does not pass state information to fhandle. For
example, fhandle may want to know how many times it's been called. This can be overcome
by saving state information inside fhandle using 'persistent' variables. For an example
see imwrite2 (which uses persistent variables with feval_arrays).
INPUTS
fhandle - function to apply to each image [see above]
params - cell array of additional parameters to fhandle (may be {} )
srcdir - directory containing images
name - [optional] base name of images
ext - [optional] extension of image
nstart - [optional] image number on which to start
nend - [optional] image number on which to end
ndigits - [optional] number of digits for filename index
OUTPUTS
X - output array [see above]
EXAMPLE
% reads in all images in directory (note that fhandle is identity!):
X = feval_images( @(x) x, {}, srcdir );
% reads in all images converting to grayscale:
X = feval_images( @(x) rgb2gray(x), {}, srcdir );
DATESTAMP
30-Apr-2006 12:00pm
See also FEVAL_ARRAYS, IMWRITE2, PERSISTENT, TICSTATUS