yeah i forgot about that whole subcode thing. ive never run into any trouble concerning that myself so it didnt cross my mind until now. and like patrickp said, dont use your current image and then convert its format. you will need to create an entirely new image from the disk and this time do it in one of the formats we suggested.
but make sure that for whatever image creating software you use, you set it up right and configure it (if necessary) so it will know to include the specific types of data that is needed from that type of disc (psx) in the image because some programs dont include the vitals, specifics and important stuff until you actually tell them to do it manually. just follow one of the guides word-for-word listed in the almighty
psx image creation tutorial(s) thread.