The standard image viewing software on computers may solve one viewer problem.
Sending more than two images may solve the other CES vs PES viewer problem.
A stereographic image can be downloaded off a web page.
Mac instructions follow. On a PC, first open with a picture viewer.
Will get something like this.
Open the same image up again using Paint.
Should get something like this.
The image can be scaled inside paint like so.
Grap and position the Picture viewer over the paint window and resize it until both images are the same width.
Now align the Windows Picture Viewer image to the edge of the Paint image.
Use your normal stereographic viewing method and the center images should all come out in various forms of 3D.
By sending three images, one center image will work for PES and the other for CES.
On a mac the method is slightly different.
On a mac first double click one file, then double click the other file. Then scale and align from there.