Have a look at the cfimage documentation - ColdFusion Help | cfimage
If gives an exact example of what you need.
writeToBrowser action Use the writeToBrowseraction to display one or more ColdFusion images directly to the browser without writing them to files. Images are displayed in PNG format. The following example shows how to reduce the size of an image and display it in the browser:
<!--- This example shows how to create a ColdFusion image from a JPEG file, resize it, and then display it in the browser as a PNG image. ---> <cfimage source="../cfdocs/images/artgallery/jeff05.jpg" action="resize" width="50%" height="50%" name="smLogo"> <cfimagesource="#smLogo#"action="writeToBrowser">
That worked for me !!
Resize and show in browser without a need to save in folder, but it will get stored in a temp folder like this CFFileServlet/_cf_image if so it will consume more space?
It wont consume much space as its only a temporary place. The image will be there for a short time (around 5 mins) then disappear.