Same image - Browser resizing

I would like to use the same image in more than one page but of different sizes. For example if the full size is 40K and I want to use the same image but a half size on another page I am wondering what "best practice" is recommended.

Is it best to create another image half size so the visitor has to download another image or to just use the same image but using the width and height tags to give the smaller size?

Does anyone know if the browser overhead of resizing is related to the size difference? ....or how it compares with the speed of downloading a new image of say 20K?

Create a new one. Don't resize from one master image.
It looks bad, and make no sense to show the same photo (40K) half the size (20K) but the browser need to download 40K.

Resize via the img src code will only affect the broswer display, not the caching; so, if the image is already cached it will save you BW (will not be downloaded twice).

So long as you scale it down precisely (eg: half the height & width) it will look fine.

In that sense, then the browser need to download 60k.. 40k+20k, a bigger download. If you did just resize the image for the second instance, the pic will already be downloaded, and all the browser needs to is resize it.

But im from the school of thought that it just makes sense to remake the image for use in the second instance regardless of the extra 20k the user downloads. The pic will look better IMO. And whats 20k with todays connections, maybe 1/4 of a second? I wouldnt worry about it.

In my eyes, resizing while using the img src width & height is amaturish.
Always resize the original photo... I mean, it doesn't even look good!

Thanks - seems to be a difference of opinion then The site in question is a Family History site and certain people (pictures) occurr on different pages at different sizes. So it is a matter of balancing how many times a particular person is likely to appear in one session.

I think it is easier to let the cache and browser display rather than creating several images of different sizes. I just need to make sure I have the proportions adjusted correctly.