New function __magick_ping__ to speed reading of images. * __magick_read__.cc (__magick_ping__): New function that only pings one of the images in a file to obtain height, width and format information. This becomes an alternative to imfinfo for internal Octave functions. Because imfinfo requires reading of the whole file and all images, this has a large speed increase, specially for multipage images. * imformats.m: use __magick_ping__() to check image format. * private/__imread__.m: use __magick_ping__() to get rows and columns of an image which is used to set the reading defaults.

(binary:application/java-vm)