This filter tells the image optimizer to upscale your images. This only makes sense with “fit-in” or “adaptive-fit-in”. This means that if an original image is 300px width by 200px height and you ask for a 600×500 image, the filter will resize it to 600×400.
Normal Image:
https://push-3272.5centscdn.com/KB_IMG/balloon_5CC.jpg
Transformed Image:
https://push-3272.5centscdn.com/KB_IMG/balloon_5CC.jpg?im=fit-in/600×500/filters:upscale()
){kind=link}