"Peter" wrote in message ...


Whereas the Jepp plates are stored as image files, and these were
obviously designed for 800x600; the format is proprietary but it is
probably something like GIF (lossless compression suited well to line
drawings) and they very possibly store 2 or 3 images of the plate to
suit the different views which JV can offer - whole page, page width,
I don't have JV handy. It's efficient; all the plates for all airports
in the world fit in 500MB or so on one CD. Every JV3 CD has all this
on it; you just need to coverage code to unlock the stuff you have
paid for


More specifically, Jepp plates are vector graphics, not raster images.
They are rendered into a raster image only at time of display,
so lines and edges won't appear fuzzy at high zoom levels.
That means each displayable image is constructed to the full resolution
of your display device only *after* you select a subsection of the chart,
such as the chart header, or the profile view, etc. for display.
That uses a little extra real-time image-processing computation,
but the result is an immensely better image than PDFs give us.