You are correct. The shorter .jpg extension was made necessary because MS-DOS and early editions of Windows had a three-character limit on extensions. .tif and .tiff are also interchangeable for the same reason.
Since small file sizes in PNG depend on the number of colors used, those using that form of compression may want to review the color scheme generators linked here: http://www.cartographersguild.com/showthread.php?t=567
Reducing your image to a few colors can greatly improve compressibility, but it makes choosing the right colors more important. Those of us who are stronger technicians than artists can use some help with that.
Bryan Ray, visual effects artist
http://www.bryanray.name
Nice links except that as I read the first line it was wrong ! A JPEG is usually 24 bit but you can also do a greyscale JPG too. Thats a single channel version. That would sound like it would be 1/3 size but usually its nowhere near as small as that but it is smaller than a color one by maybe 20%.
JPEG stands for Joint Photographic Experts Group - a sort of unofficial consortium when JPG was being developed. Since DOS based file suffixes have only 3 letters, thus JPG instead of JPEG.
Gamer Printshop Publishing, Starfinder RPG modules and supplements, Map Products, Map Symbol Sets and Map Making Tutorial Guide
DrivethruRPG store
Artstation Gallery - Maps and 3D illustrations
In in PhotoShop 7, I've found "Save for Web..." (to jpg) gives much better sizes than "Save as..." (to jpg). I'm sure there is a trade off but they look the same on my uncalibrated lcd monitor.
The same holds true for PNG. You get a lot more controls to fine-tune your image, including specifying a palette and the degree of anti-aliasing that occurs. You also get instant feedback on how large the resulting file will be, so you can see exactly how much savings each option gives you.
Bryan Ray, visual effects artist
http://www.bryanray.name
Hmm ... have to look at this, I might be able to get a 100px=5' image of the deck plan
(2500x2100 currently weighing in 88kb)
Last edited by Valarian; 05-13-2008 at 08:14 AM.
Google Groups for FGII Games:
European FG2 RPG - Fridays & Sundays (8pm UK time)
Using Ultimate FGII and can accept unlicensed player connections on some of the games
I looked at your palette as soon as you posted it and its a 256 version and most of it is unused. I would think that you could do your pic in 16 col and go with a 4 bit PNG which would be a little less than your 8 bit version. If you made a custom palette of 8 shades of grey, two are three bright greens and that dark blue then you would probably have almost all of it done in about 12 out of the 16. Make sure that you go for nearest colour matching when transforming the palette tho. No dithering or half-toning or else it will shoot up the file size.