The Microsoft HD Photo plug-in for Adobe Photoshop is now available for download from the MS website. The plug-in is designed for use with the CS2 or CS3 versions of Adobe Photoshop software running under Microsoft Windows XP, Microsoft Windows Vista or Mac OS X.
HD Photo evolved from Windows Media Photo and will soon officially become JPEG XR to replace the aging JPEG image file format.
HD Photo is an image codec that gives a high-dynamic-range image encoding while requiring only integer operations (with no divides) for both compression and decompression. It supports monochrome, RGB, CMYK and even n-channel color representation, using up to 16-bit unsigned integer representation, or up to 32-bit fixed point or floating point representation, and also supports RGBE Radiance.
What it all means basically is that it will be better than JPEG as a still-image compression algorithm and file format for continuous tone photographic images. The HD Photo plug-in supports a wide range of pixel formats (including high dynamic range, wide gamut formats) and numerous advanced HD Photo features.
To be able to open and save any HD Photo file (.wdp or .hdp) in Adobe Photoshop, you need to install this plug-in.