Tim,

incidentally I stumbled across 1x.com today for the first time. It looks challenging...

Prieni

Bugger! You beat me to it, damn

No no, seriously now: Well done, Tim! I had little time submitting recently and got three shots declined (I just submitted enough to make it 100 if all would have been accepted).
The first one for me is the strongest of the series, the Billionaires club is my #2.

Prieni

WOW! A true master!

And I thought my ratio of 97 of 273 submitted wasn't bad. Shows what a tosser I am...

Prieni

They are indeed very strong pictures. And seeing them in a series like this leaves me in stunned silence.

Chapeau and bravo! Love it.

Prieni

Don't worry, Stefan, as I said, it's all a bit tongue in cheek.

Prieni

Yes, usually 200k is fine, there is the odd occasion, though, where it can make a visible difference.

But we are digressing. The 80% question was only a tongue in cheek comment, but if we would take it more serious, what would it mean?

A 3:2 aspect ratio image with 800 pixels on the long edge has 533 pixels on the shorter edges. 8 bit colour depth means we have 3 bytes per pixel => 800 * 533 * 3 = 1,279,200 bytes or about 1.2 MB. (BTW: That is the size of a BMP file with these dimensions).

Now it starts to depend on the JPEG algorithms. If I take a sample picture in Photopaint (I have to take what I have at work, I'm afraid) and save it in the best possible quality (compression 0 and smoothing 0) this particular image ends up at 273 kB.
[IMG]http://i156.photobucket.com/albums/t5/Prieni/Pentax%20user/_PRI0550_100pc.jpg[/IMG]
This is about 21 % of the original size. Is that compressed 80% (or 79 %, to be more precise) ?

Saving it again, this time with compression 4 and smoothing 0 it is only half the size (142 kB) of the other one. (And, to further emphasize your earlier point, it doesn't look any different.:shock
[IMG]http://i156.photobucket.com/albums/t5/Prieni/Pentax%20user/_PRI0550_50pc.jpg[/IMG]

Is that now compressed 90% ?

Prieni

I doubt it. AFAIK there is no such beast as an uncompressed JPG. There is a specification for losless compression in the JPEG standard, but uncompressed?

This is, of course, in the realms of bean counting.

I second the suggestion of a maximum file size, 200k does sound a bit on the low end, though.

Prieni

What is the 80% compression related to? My version of PS gives me a choice of 1 to 12 on the quality (and three different settings on the JPG format).

Prieni

Excellent! You clocked up quite a collection, I see the first century looming...

Prieni

Jelly fish squeezed through chicken wire
[IMG]http://i156.photobucket.com/albums/t5/Prieni/Pentax%20user/_PRI0651.jpg[/IMG]

Taken on the research vessel Maria S. Merian in the Baltic. A colleague had dipped his porewater sampler for the first time and when it came back on board two pieces of jelly fish stuck to the chicken wire.

EXIF:
Camera Maker: PENTAX
Camera Model: PENTAX K20D
Lens: smc PENTAX-DA* 16-50mm F2.8 ED AL [IF] SDM
Image Date: 2010-08-07 13:40:07 +0100
Focal Length: 50.0mm (35mm equivalent: 75mm)
Aperture: f/9.5
Exposure Time: 0.0040 s (1/250)
ISO equiv: 100
Exposure Bias: none
Metering Mode: Matrix
Exposure: aperture priority (semi-auto)
Flash Fired: No
Color Space: sRGB

Prieni