title: C++ libraries to manipulate images
body: <p>Do you know any open source/free software C++ libraries to manipulate images in these formats:
  .jpg .gif .png .bmp ? The more formats it supports, the better. I am implementing a free program in C++ which hides a text file into one or more images, using <a href="http://en.wikipedia.org/wiki/Steganography" rel="nofollow noreferrer">steganography</a>.</p>
  
  <p>I am working under Unix.</p>