Render a PDF page to an image

Renders one page of a PDF as a PNG and stores it as a new file. ```json { "page": 1, "scale": 2 } ``` `page` is 1-based and defaults to the first page. `scale` runs from 0.1 to 6 and defaults to 2; the long edge is capped at 4000 pixels whatever you ask for. Only a PDF can be rendered — convert first with [convert/pdf](https://docs.cloudraker.com/api/cloud-raker-api/tools/convert-file-to-pdf). **Learn more:** [Working with files](https://docs.cloudraker.com/developers/files)