[magick-users] How to properly downsize an image

[T o n g]

Hi, 

What's the proper way to downsize an image? 

I want to downsize my 1152x864 image to 500x, so I did:

 convert -resize 500x screenshot.png screenshot-thumbnail.png

I was thinking that the downsized thumbnail should be around 1/4 of the
original size, but I am totally wrong:

 $ identify screenshot*
 screenshot-thumbnail.png PNG 500x375 500x375+0+0 DirectClass 509kb 
 screenshot.png[1] PNG 1152x864 1152x864+0+0 DirectClass 82kb 

 $ ls -l screenshot*
 -rw-r--r-- 1 tong tong 521280 03-29 16:54 screenshot-thumbnail.png
 -rw-r--r-- 1 tong tong  83876 2007-01-01  screenshot.png

The size is not smaller but over 6 times bigger. 

I remember that I need to something extra, so I tried the following, but
that didn't help. The thumbnail is the same size as before:

 convert -size 500x375 -resize 500x screenshot.png screenshot-thumbnail.png

Please help. 

Thanks

-- 
Tong (remove underscore(s) to reply)
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