Work out image dimensions from filesize

Is this possible?

Say i had a 30mb RGB TIFF file.

Is it possible to work out the actual image dimesions for that file?

Thanks

Mark

haha - uhh - let's see:
you could have an image 1 pixel in width and 2134672163541327464 pixels in length

hihi @ mihai.

Why do you need this?
I mean why just you don't open the file in photoshop and check what's the dimension?

I would doubt it. You may be able estimate something similar....maybe screw with some bit/byte calculations......but thats as far as your going to get. Why would you need to work backwards anyway?? It probably would be way easier just to read whatever header information is available.

The reason is, i am about to buy a photo from and image library for a client, but for some reason, when telling you the costs for the image at different sizes, they give you the prices based on the filesize, not the image size!?

Thats no use to me. This is for a scottish police recruitment ad that is going to be used on A4 posters. How do i know what size image to go for?

The options for purchasing are as follows:

1 - 30MB RGB TIFF (delivered as JPG) £ 160
2 - 12-14MB TIFF (delivered as JPG) £ 99
3 - 4.5MB RGB TIFF (delivered as JPG) £ 65
4 - 1.1MB RGB TIFF (delivered as JPG) £ 40

how do i know which image will be good enough for roughly A4 size.

Thanks

Mark

Uhm that's a crappy image library!
As you say it's impossible to know.
Just send them a mail and ask about the sizes before you go and buy something.
Hmm what's that delivered as JPG?
What the point with the TIFF and the size because they get much smaller in .JPG format...
Wierd...

i know, i just can't understand it?

The image library in question is www.imagestate.co.uk if you are interested.

Mark

1MB - 72 dpi - 6"x10"

10MB - 300 dpi - 5"x7"

28MB - 300 dpi - 9"x12"

48MB - 300 dpi - 11"x17"

lifted from photodisc.com, hope that helps

chris