Image (Photo) Compression

[lvzardoz]

Here's a note I sent to our Mensa message board. I thought others might also find it useful:

Reference: http://www.uniQon.com/smaller

I don't want to pick on Mitch, but a goodbye photo he sent to the Hiking SIG will be a good example. (I am sure Mitch wanted to leave us all with the highest quality photo.)

Mitch didn't send a BMP file. That's good. Nobody should. He sent the appropriate file type: JPG. He sent a very large image 1280 by 960 pixels, a size which most people probably can't view without scrolling on their smaller 1024x768 or 800x600 computer screens.

Let's say that Mitch had emailed his photo in that bad BMP file format instead or let's say he sent a smaller 640x480 photo which is a comfortable size for most computer viewers. Let's look at the file sizes:

3686K Mitch_Bye_1280.BMP (3.7MB)
_836K Mitch_Bye_1280.GIF
_320K Mitch_Bye_1280.JPG (emailed)
_156K Mitch_Bye_1280_optimized.JPG
_922K Mitch_Bye_640.BMP
_237K Mitch_Bye_640.GIF
__77K Mitch_Bye_640.JPG
__42K Mitch_Bye_640_optimized.JPG

So, how do download times compare?
If you're still using a slow 28K modem:

111 seconds: Mitch's original 320K 1280x960 photo
_14 seconds: the 42K 640x480 medium compression photo

How about quality? The 14 second photo:

http://www.uniQon.com/mitchbye.jpg

/ Rev B / aka Bob Carroll

[Still Shady]

not bad

[lookout]

Yes. Perhaps a little image sharpening would make it even better without too much gain in filesize.