How is going upscaling the image in PS4 ?

Solution
Upscaling is when the console or PC renders the image at a lower resolution, and that's then fitted onto the higher-resolution monitor or TV. PCs can do that easily, and you can generally pick a wide range of resolutions.

Native 4K means there's no upscaling - the image is rendered at the same 4K resolution as the TV or monitor has. That will look much, much better than an upscaled image.

Upscaling often looks very bad because the lower resolution doesn't fit neatly on the screen's resolution. Pixels have to be stretched unevenly.
Upscaling is when the console or PC renders the image at a lower resolution, and that's then fitted onto the higher-resolution monitor or TV. PCs can do that easily, and you can generally pick a wide range of resolutions.

Native 4K means there's no upscaling - the image is rendered at the same 4K resolution as the TV or monitor has. That will look much, much better than an upscaled image.

Upscaling often looks very bad because the lower resolution doesn't fit neatly on the screen's resolution. Pixels have to be stretched unevenly.
 
Solution