Adobe Photoshop PSD file reader

Functions to read images and get metadata from Adobe Photoshop PSD files.

This is a suite of functions that read images and metadata from Adobe Photoshop PSD files. These files can be used independently or in IMREAD and IMFINFO via IMFORMATS.
Currently only the image pixels from the base layer are imported. Additional layers, paths, masks, and adjustments can be in the file but do not affect the image that is loaded.

The metadata support is limited to basic details about the image (dimensions, bit depth, number of samples, etc.).

These functions are based on the file format description for Photoshop 4, but they appear to work for Photoshop 7 files. I haven't tested on files generated by Photoshop CS.