Information on transformations made by Image Optimizer.
Fastly writes this header into responses. It is proprietary to Fastly.
This header is written by Fastly when a response is transformed by Image Optimizer. It provides detail on the input format (
ifmt), dimensions (
idim), and size in bytes (
ifsz), and also the output format (
ofmt), dimensions (
odim), and size in bytes (
The header's value is a space-delimited string of key/value pairs. These pairs can appear in any order.
ifsz=<input size in bytes>idim=<input dimensions>ifmt=<input format>ofsz=<output size in bytes>odim=<output dimensions>ofmt=<output format>
ifsz=108501 idim=827x788 ifmt=jpeg ofsz=13066 odim=300x286 ofmt=jpeg