This is only an abstract of the corresponding   German page

Here you see four pictures with the same view in different seasons. The size of the original photos is 1.152 x 864 in pixels. At the first moment they seem to be congruent, but that is not true.

The differences are

• a slight distortion compared with the first photo in autumn,
• the position of the camera may have been a little bit nearer or farer away, resulting in larger or smaller objects in the image.
• the direction of the camera was not always exactly the same. In consequence the display details differ.

To correct the aberrations you have to look for objects in the images which can be used as fixed-points. Then you have to determine the coordinates of these points.

The coordinates and the calculated numbers can be read in the tables   Koordinaten … von Überblendbildern.

The fixed-points number 3 and 4 were choosen for the calculation with the steps

• turning the image clockwise or anticlockwise (these road pictures didn't need it really),
• adjusting the size. Each picture must have the same differences
  x₃-x₄ and y₃-y₄.
• shifting the photos on new blank larger pictures till the coordinates of one fixed-point (No 3) (in the larger pictures!) correspond in each picture.

Reading the coordinates of the corners of the photos inside the large pictures you can find out the position and size of the largest possible common image. You cut it out of each picture and now have congruent photos.

The normal procedure of picture editing follows, contrast, brightness, sharpness and the final size for the webpage.

Now you can use a flash-, video- or gif-animation-program.

There is no science, no mysticism in this work, only accuracy and endurance.