j2k_to_image(1) -i Image_6.jp2 -o Image_6.bmp
convert a J2K, JP2 or JPT file into a PGM, PPM, PNM, PGX or BMP file
-i source
    J2K, JP2 or JPT file to convert
-o destination
    PGM, PPM, PNM, PGX or BMP file to output to
source manpages: j2k_to_image