Stereogramm-Decoder, aka StereoDecoder, can open an autostereogram and display the 3D image (that may otherwise be difficult to see). It is useful for anyone who struggles with viewing autostereograms, but it does require access to another graphics program that can be used to measure the pattern width (as explained in Stereogramm-Decoder). The GIMP has a measure tool that can be used for this purpose.

I have not found a way to save the image generated by Stereogramm-Decoder, but it's possible to just take a screenshot.