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,prms{:}) 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 similar to fevalArrays, except instead of operating on images in
memory it operates on images on disk. For long operations shows progress
info.
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 an 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 [nStr,nEnd]. For example, to operate on images
"rats0003.tif ... rats0113.tif" in directory '../rats/' use:
fevalImages( fHandle, prms, '../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.
A limitation of fevalImages 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 fevalArrays).
USAGE
X = fevalImages( fHandle, prms, srcDir, [name], [ext],
[nStr], [nEnd], [nDigits] )
INPUTS
fHandle - function to apply to each image [see above]
prms - cell array of additional parameters to fHandle (may be {} )
srcDir - directory containing images
name - [] base name of images
ext - [] extension of image
nStr - [] image number on which to start
nEnd - [] image number on which to end
nDigits - [] 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 = fevalImages( @(x) x, {}, srcDir );
% reads in different sized images into cell array:
X = fevalImages( @(x) {x}, {}, srcDir );
% reads in all images converting to grayscale:
X = fevalImages( @(x) rgb2gray(x), {}, srcDir );
See also FEVALARRAYS, IMWRITE2, PERSISTENT, TICSTATUS
Piotr's Computer Vision Matlab Toolbox Version 2.40
Copyright 2014 Piotr Dollar. [pdollar-at-gmail.com]
Licensed under the Simplified BSD License [see external/bsd.txt]