image sizes and file sizes... conflicting information

[harrytewkesbury]

Hello.. just a quck question from a newbie...
When creating a thumbnail, i have had two conflicting pieces of information. One source has told me that using the WIDTH and HEIGHT attributes for the source image sizes the image down accordingly. That is to say that a 50x50 thumb is half the file size of the SAME image at 100x100. Another source said that this simply is not the case...
Who's right? I ask because i would prefer not to have to copy and resize all my images just for thumbnail purposes.

 

[chrisgill369]

the file size of a 50x50 image will be 1/4 of the 100x100 file size.

If you draw a square on a piece of paper that is 100mm x 100mm and then draw a 50mm x 50mm inside it you will see that it only takes up 1/4 of the larger square.

 

[harrytewkesbury]

yes, but with a scalable image does the FILE size change? The pixels on the screen will be smaller granted, but does the browser download the full sized image and then simply display it as a smaller image on the screen?