Writing Jpeg data to SD card


I would like to write JPEG data to the SDcard. Can I just write byte by byte of the Jpeg data to a same file using filename pic.jpg in the SDcard?

When I view the Jpeg data from the serial monitor, this data are in decimal format. Do I need to convert these data to hexdecimal before saving it to the SD card?

Is there a way for testing purpose to copy these Jpeg data to a wordpad and save it as a .jpg file? So that I can view the Jpeg image without going thru the SD card first.