So far, we have solved the zooming by reducing the resolution of the more detailed map by 50% using the resolution reduction technique derived from JBIG. This methods aims at preserving all lines in the image. In the case of more demanding use, we should implement non-portable zooming in order to create any intermediate level. There exist straightforward methods for photographic images but they do not apply to binary and graphics images as such. Alternative method exists but the open question is, how well they suit to this particular application. For example, the user might, opposite to what is the goal in the JBIG technique, to filter out less relevant information instead of preserving all details.

Another situation happens when the user wants to zoom in beyond the most detailed map. If we apply a simple pixel copying technique, we will produce jaggedness and blockiness into the image. At the same time, there is enough information in the image to conclude the shape of the lines and, in principle, we could simulate vector image zooming at any resolution. In this part, the goals is to study into what extent we can develop the zooming in practice.  

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