Re:spark photos (was: Spark-gap sparks vs. solid-state sparks)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

>
> And speaking of sparks...I've just engaged my son to take some fine
> photos of my coil running.  Multiple-exposure images, of course, and
> quite spectacular.  He used a 4x5 view camera to make color slides & then
> scanned the images into his computer & ran me a couple of 8" x 10"
> prints.
>
> I hope to make up a small Web site soon, after learning how, & perhaps
> put it on hot-streamer if Terry's hospitality there is still on offer.
> So far, some 3.5 MB for a 300 dpi image and a whopping 15-odd for 600 so
> perhaps I wouldn't use the latter.
>
You'll find that jpeg will compress those pretty well even if you set the
quality very high (pretty lossless, that is).  The trick is making sure your
background is really uniform in color, and likewise, that of any of the
other photo details that aren't important. A little work with photoshop and
the smudge tool makes a huge difference in the size of a scanned photo as a
file.  Inevitably, large areas of the photo which are "really" the same
color, show up with small fluctuations (due to noise in the digitizing
process). The compression process then tries to keep all that "information"
Smudging them all to the same color makes it compress real well.

This is a useful trick for this sort of image (solar eclipses have the same
problem... you KNOW that the center of the sun is uniformly black in the
original image, so why not just make it so)