Gallery- thumbnails problem

Hi everyone. i have installed Gallery Extension + Rmagick. When im
adding images to gallery tumbnails for JPG files are not generated. It
works fine for files like(*.ico, *.gif) - images are thumbnails are
generated. I have installed imagemagick do i have to install something
more(like graphicsmagic)? pls help

it think it is becouse i miss library for r magick.
error:“No decode delegate for this image format.”

if found JPG library on
but i dont know kow to install it. im using gentoo