opj_decompress: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/opj_decompress - from package: libopenjp2-tools

You may install the required package with command apt-get install {package}

Error in other languages:
opj_decompress: bevel nie gevind nie
opj_decompress: comandă negăsită
opj_decompress: comando não encontrado
opj_decompress: commande introuvable
opj_decompress: command not found
opj_decompress: käsku ei ole
opj_decompress: không tìm thấy lệnh
opj_decompress: komanda nerasta
opj_decompress: Kommando nicht gefunden.
opj_decompress: kommandot finns inte
opj_decompress: komut yok
opj_decompress: nie znaleziono polecenia
opj_decompress: níor aimsíodh an t-ordú
opj_decompress: no se encontró la orden
opj_decompress: no s'ha trobat l'ordre
opj_decompress: opdracht niet gevonden
opj_decompress: parancs nem található
opj_decompress: perintah tidak ditemukan
opj_decompress: príkaz nenájdený
opj_decompress: příkaz nenalezen
opj_decompress: команда не найдена
opj_decompress: командата не е открита
opj_decompress: 命令找不到
opj_decompress: コマンドが見つかりません