Glossary
Plain-language definitions of the file, image and audio terms used across Frespy.
- Lossless compression
- A way to reduce file size without discarding any data, so the image or audio is identical to the original. PNG and WAV are lossless.
- Lossy compression
- Shrinks files by permanently removing detail the eye or ear is least likely to notice. JPG and MP3 are lossy.
- Alpha channel
- The transparency layer in an image. Formats like PNG, WebP and AVIF support it; JPG does not.
- Bitrate
- How much data is used per second of audio or video. Higher bitrate usually means better quality and larger files.
- EXIF metadata
- Hidden information stored in a photo, such as camera model, settings and GPS location. Stripping it protects privacy.
- Base64
- An encoding that represents binary data as text. It is reversible and is not encryption.
- Hash
- A fixed-length fingerprint of data. The same input always produces the same hash, but you cannot reverse it back to the original.
- UUID
- A universally unique identifier. Version 4 UUIDs are random and used to label records without coordination.
- Slug
- The clean, readable part of a URL made of lowercase words and hyphens, like "how-to-merge-pdf".
- JWT
- A JSON Web Token: a compact, signed token with a header, payload and signature, used for authentication.
- Codec
- Software that encodes and decodes media. AV1, the basis of AVIF, is a modern, efficient video codec.
- DPI / resolution
- How many pixels or dots make up an image. Higher resolution looks sharper, especially when printed.
- Aspect ratio
- The proportional relationship between an image width and height, such as 16:9 or 1:1.
- Quiet zone
- The empty margin around a QR code that helps scanners detect and read it reliably.
- Vector vs raster
- Vector images (SVG) scale to any size without blur; raster images (PNG, JPG) are made of fixed pixels.