JPEG image file
SPF is a file extension for an image file in a format developed by the Joint Photographic Experts Group. SPF stands for Still Picture interchange file Format, also referred to as SPIFF. SPF files allow JPEG and JBIG (bitonal) bit streams to be exchanged between a variety of platforms and applications.
SPF files offer more features than the current JPEG standard and is backwards compatible (a JFIF decoder can understand most SPIFF images). SPF files might also have the JPG suffix. SPF files can be opened and edited by most image editing software, including Adobe Photoshop.
Learn more about .SPF files:
Visit the Adobe Photoshop web page.
Read the Image FAQ at ITKnowledgeExchange.com.