|
10./12/2006 2247z
As usual Markus, all is OK here!
VY 73: Jeff F6CWN
----- Original Message -----
Sent: Sunday, December 10, 2006 11:23
PM
Subject: LF: Grabber image format
Dear LF Group,
today I have changed the
8-bit image format for my grabber from .gif to .png. This appears to save some
20% of volume, due to a more effective lossless compression
algorithm.
When I started grabber operation I had tried various
flavours of .jpg first, but the halved colour resolution soon turned out
inadequate for many fine details on the colour-DF display. With 256 colours
and lossless compression, resolution looked much better, but very weak signals
and noise details tended to get masked off by too few dark palette entries. I
got around that by brightening the original bitmap (gamma=1.49 in IrfanView)
before reducing to 8 bits, and then darkening the colour table again
(gamma=0.67) before uploading.
Please report if you find any
difficulties displaying or downloading the .png images.
73 de Markus,
DF6NM
http://members.aol.com/df6nm/Grabber.htm
|
