Usage: upscale()
This filter tells thumbor 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 600x500 image, the filter will resize it to 600x400.
No arguments allowed.
http://localhost:8888/unsafe/fit-in/600x500/filters:upscale()/https://raw.githubusercontent.com/thumbor/thumbor/e86324e49d7e53acc2a8057e43f3fdd2ca5cea75/docs/images/dice_transparent_background.png