Standard ZIP compression, well, approximately...

Hi all, a very open ended topic, wondering if anyone has links to firther info.

Does anyone one know the approximate compression applied to the following file type.

GIF
JPEG
BMP

From playing about I get BMP's to be around 75%, JPEGS and GIFS around 1/2%, if that.

Is there any decent info available? Having approximate values will increase the efficenecy of an app im developing 10 fold...

Cheers
Taz

Look at http://www.wotsit.org/ for different file formats.

If you're looking for % of compression, that really changes a lot depending on the image you're compressing. Especially with the GIF format.

For instance:

1024x1024 white image:

bmp: 3,145,782 bytes (no compression)
gif: 2,668 bytes
jpg: 17,011 bytes (compression: 50)
jpg: 17,011 bytes (compression: 75)

1024x1024 noisy image:

bmp: 3,145,782 bytes (no compression)
gif: 563,175 bytes
jpg: 442,754 bytes (compression: 50)
jpg: 577,701 bytes (compression: 75)

700x1043 Photo:
bmp: 2,190,354
gif: 380,034
jpg: 66,930 (@50)
jpg: 103,120 (@75)

note: the jpgs looks a whole lot better then the gif, since the gif reduces the image to 256 colors.

477x570 colored drawing, no shading:
bmp: 274,678
gif: 21,420
jpg: 23,618 (@50)
jpg: 31,422 (@75)

note: in this case, the gif looked better since the jpgs cause artifacts, and fewer then 256 colors were used in the original.

An interesting thing I didn't expect was the white image stayed the same size for the different jpg compression settings. But maybe the software I'm using does some optimizations.

wow, thanks for the reply, really appreciate it.

Did you get those figures from playing around or from a source on the internet?

Thanks again.
Taz

I did them myself. It only took a few minutes.

Ok, thanks alot. I'll keep experimenting with the other filetypes im after

Taz