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LF: Grabber image format

To: [email protected]
Subject: LF: Grabber image format
From: [email protected]
Date: Sun, 10 Dec 2006 17:23:58 EST
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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
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