Guides

edit

A guide solves one common task from start to end: what the task needs, the complete code, then the choices you may want to change, with links to the pages that describe each option in detail. Start from the guide closest to your task and adapt it.

Create thumbnails: small previews of photos and animations, upright, fitted, cropped or letterboxed, in a compact format.
Convert between formats: convert a file or a whole folder, and decide what happens to transparency, 16-bit samples, animations and metadata that the target format cannot store.
Process animated images: resize or edit GIF, APNG and WebP animations, change their speed or their loop count, extract a frame, and choose the palette of a GIF.
Handle photos from phones and cameras: load HEIC, AVIF and JPEG photos, turn them upright, convert their colors to sRGB and publish them as JPEG or WebP.
Add a watermark: draw a text or a logo over an image or an animation, half transparent.
Process untrusted uploads: check the format and the size of a file before decoding it, bound the resources it can use, handle every error, and re-encode it.
Strip or edit metadata: remove the GPS position and the other private data of a photo, keep its colors, and edit its metadata.