why do we face issue of upscaling?
by the video i understood the concept in way that ,
user uploads image of lets say 3 mB wth high pixel count.
now that 3mB image will be compressed to fewer pixels and store into database(less pixels less size).
now when the webapage is loaded why does a 3mB image be shown to user as that 3mB image is not even stored somewhere.
does the tutor mena it will be upscaled(interpolated ) to higher pixel image when webpage is requested?
also if possbile please answer type of compression
Drupal Creating-New-Content-Types 07-08 min 30-40 sec
It is not that the 3 MB image will be compressed to smaller pixels. It is the same size (3MB) that is downloaded to the user's browser (or mobile) and it is the browser displays the large file in a smaller window.
In this case there is no upscaling or downsizing. There is no compression algorithm used at the drupal backend, as it is simply the browser which displays (by its own compression algorithms).
In a later tutorial "Controlling the display of images" you will learn how to optimize the display of images: small image size for thumbnails, large for details. This way your browser need to download only the required size of the file (say 100 kb for thumbnail, and 3MB for detail), when explicitly requested by the user.