makethumbdir

Create thumbnails for all MATLAB-writeable image types of a given extension in a selected directory.

Syntax: MAKETHUMBDIR(MAXSIZE, KEEPFRAC)

The user is prompted to select any image in the folder to be "thumbnailed." The mfile will then create thumbnails for all MATLAB-writeable image types having the same extension as the selected image and residing in the selected directory, and store them in a thumbnail folder within that directory. Thumbnails will have the same name as their parent images, although their paths will necessarily be different.

ARGUMENTS:

Two OPTIONAL ARGUMENTS, as follows:

MAXSIZE is the maximum size of the thumbnail, in kB. The default value of MAXSIZE is 32 (kB).Note that some image writing algorithms produce images that are further compressed; maxsize is a target for the number of bytes in an uncompressed version of the thumbnail image; thumbnails will not be larger than maxsize, but they may be considerably smaller.

KEEPFRAC (which, if it is provided, must be a positive integer greater than 1) determines the number of rows and columns maintained from the original image. A thumbnail for a "2-dimensional" (eg., indexed or grayscale) image should approach 1/keepfrac^2 times the size of its parent image, or 3/keepfrac^2 for "3-dimensional" (eg., truecolor or RGB) images. For example, if the value is set to 8, a thumbnail for a grayscale image will approach 1/64th the size of the parent image.

BY DEFAULT, the value is set dynamically for each parent image to target a thumbnail that is no larger than MAXSIZE kB. However, if KEEPFRAC is provided, MAXSIZE is ignored. The program supports all image file types writeable by MATLAB:

JPEG, TIFF, BMP, PNG, HDF, PCX, or XWD.

The user will be presented with a uigetfile dialog box in which to select a single image to thumbnail. All images of the same extension/type in the same folder will be similarly thumbnailed.

EXAMPLE: makethumbdir %Creates a default series of thumbnails of maximum 32 kB.

makethumbdir(64) %May be of higher resolution, with images possibly ranging up to 64 kB.
makethumbdir([],4) %Writes thumbnails comprising every 4th row and column
makethumbdir(64,4) %Writes thumbnails comprising every 4th row and column

(first argument is ignored)

Written by Brett Shoelson ([e-mail]; [e-mail]).
Last update 1/31/03.
Tested under R12.1 and R13