Disables features that are enabled by default.

IMPORTANT: In Fastly services in which IO was enabled after April 2018, upscale is already disabled by default. It can be enabled with the enable parameter.



Allowed values

upscalePrevent images being resized such that the output image's dimensions are larger than the source image.


  1. Image upscaling is discouraged because it increases both the file size and delivery time of the image to the end user with no visual improvement. We recommend handling upscaling on the client-side (e.g., using a web browser or native application).
  2. The upscale value must be used with the width, height, or dpr parameters to see any effect in the output image.


Click the links to view the transformed image using a demo Fastly IO service.

Example usageDescription
?width=2560&disable=upscaleAttempt to resize the image to 2560px wide but do not exceed the natural width of the source image