html - Sitecore : image size when using <img> in rich text -

i know it's possible when writing code ask sitecore image of specific height , width. if there 1 large/detailed image in sitecore, sitecore return resized image ( instead of using large image , showing in smaller ).

but need insert images rich text. if use <img src="somepath" height="100" width="100">, have same effect , sitecore fetch smaller version of image ( possibly in cache ). or send large image , use pure css show smaller image ?

in sitecore 8 if add media library image rich text field , set image height , width editor (see screenshot), sitecore generate image src this

<img src="/~/media/.....jpg?h=84&w=149" /> 

this means image resized server side sitecore before returning client browser.

but if edit html of rich text content manually , create image tag

<img src="/~/media/...jpg" width="84" height="149" />` 

sitecore not resize image on server side you.