It appears that jpeg to pes conversion represents attempts to create embroidery designs for Brother machines (.pes) from common JPEG pictures (.jpg, .jpeg). Brother PES format is one of the most common embroidery file types so it is usually well-supported in various embroidery programs, the trouble is usually in finding one with decent digitizing function.
This function is needed for transformation of raster (bitmap) data to vector format and works best for simple geometric shapes, logos and similar stuff, but poorly for photos and other similar complex images.
Updated: June 27, 2023