Hemera Photo-Object is a raster image format used by Hemera Technologies in their clip art software titles.
Hemera's Photo-Objects image format is similar to other formats sometimes referred to as images with transparency or images that have an associated Mask or Alpha Channel. Unlike typical photographic quality image formats that support transparency, Hemera's Photo-Object image format (.HPI) uses little disk space which allows thousands of images to be contained on a single CD-ROM.
Hemera's Photo-Objects are totally background independent meaning that each image can be placed on top of any other background. You can drag and drop the image into your wordprocessor, presentations program, or graphics application or use the Export Wizard included with Photo-Objects. 
Hemera Technologies bought rights to all Corel Photos, Clipart in the year 2000. 
The HPI file format header begins with hex values "
89 48 50 49" followed shortly after by the jpeg header at byte 32.