PngToJpg(sImage) : string
This function was first created for a specific macro (so has limited use) but has since been make public, so all macro authors can use. Note that the function name is something of a misnomer as any (supported) image file can be converted to JPG
sImage - This is the string representation of the image file. You would normally create this string by using the GetFile() function to grab the image contents from a disk file.
The return sting is the image data in JPG format. You would normally then write this string to a file using the PutFile() function.