Theory : Janorama

For those who are interested in how Janorama works, I want to explain the basics of displaying a panoramic picture with the help of a few drawings and pictures.
You have to imaging the panoramic picture wrapped around the viewer like a cylinder. The problem is, that we usually have a flat display - e.g. a monitor - in front of us, which is drawn as a rectangle in the drawing.
As you might have expected there is a lot of math involved here as shown below the geometric figures. Basicly four formulars are used to calculate the relation between a pixel in the source image and the destination rendering:

Janorama processes all pixels on the screen and fetches the corresponding color information in the source image. You can think of this process as cutting out an oval - with straight left and right sides - and stretching it into a rectangle.

Let's get back to our example: The image in the back is a part of a source panoramic image. Please check this by taking a look at the original picture.
The street and the parliament building are bended because the optical proportions got distorted at the moment this picture was taken. As a matter of fact the photographer of a panoramic picture is absolutly satisfied with his work at this point - only a programmer asks himself how this distortion can be taken back.
You can see the result of Janoramas efforts on the picture in the front - the street and the building are displayed straight.