[WriteLog] Screen Prints (long) ... minor correction

Hsu, Aaron aaron.hsu@unistudios.com
Tue, 17 Oct 2000 13:08:03 -0700

Whoops...minor error in the calcs.  Each pixel is represented by 1-bit, not 1-byte as in my calcs.  Corrected version below, but I'm sure you got the general idea.   =)

> ----------
> From doing many screen prints for documentation, let me offer one piece of advice...
> Reduce the screen resolution and bit-depth (number of colors) the the absolute minimum required for your screen shot.
> I once was given a document that was only 4 pages long, but took up 47MB of drive space.  It consisted of two paragraphs of text and a few screen shots.  Not only did it take up a LOT of space, but most people couldn't open it...it was just too darn big!  
> The main culprit in large filesize screen shots (or any photograph in general) is the color depth.  Every one byte (8-bit) increase in color depth will increase the filesize of an uncompressed picture by 2.  HxV resolution also plays a major role and it's closely tied to the bit-depth.  Here are some uncompressed calcs...
> 640x480x8-bit (256 colors) = 307K
> 640x480-16-bit (64K colors) = 614K
> 640x480x24-bit (16M colors) = 922K
> 800x600x8-bit (256 colors) = 480K
1024x768x24-bit (16M colors) = 2.4M 

> If you send a screen print via e-mail, it's best to use a common "compressed" format, such as .JPG.  However, don't go overboard on the compression as he resulting image will become pixelated (equiv to "grainy").  I generally use a 75% quality setting for low res pics, and 50 to 60% for high res pics (or even 30%).  Proper use of picture compression can yield excellent results.  I have made 50K .JPG's that look much better many 200K+ files you'll find on the 'net .  For printing, a TIFF is preferred, but filesizes are large.
> Alright, I've digressed enough.  73 and happy screen printing!
>   - Aaron Hsu, KD6DAE
>     [athsu]@unistudios.com
>     [kd6dae]@arrl.net
>     No-QRO Int'l #1,000,006
>      . -..- - .-. .-   " .... . .- ...- -.-- "
> p.s. The best utility I use to change display resolutions on the fly is the "ResMan" util.  It's available as a Win95A "PowerToy" and is standard wth Win95 OSR2 and Win98.  It runs in the System Tray and allows changing resolutions and bit-depth on the fly.  Some video drivers also have a similar function.
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