invert_raw_image: 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/invert_raw_image - from package: minc-tools

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

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