Image Formats Explained: JPEG, PNG, WEBP and GIF Compression — Photo Compressor Documentation

It helps to separate two operations people often lump together. Compressing changes how the same pixels are stored on disk — fewer bytes, same picture dimensions. Resizing removes pixels outright, producing a physically smaller image. The Photo Compressor extension compresses; it does not change resolution, so a 4000×3000 photo stays 4000×3000 pixels after processing, just represented in fewer bytes.

The extension reads and writes four formats end to end: JPEG, PNG, WEBP and GIF . Each has its own ceiling, its own transparency support, and its own typical use case, summarized below.

EXIF metadata — the capture date, camera model, lens settings, and sometimes GPS coordinates embedded by a camera or phone — follows the CIPA DC-008 Exif standard. When the extension re-encodes a file through the browser’s Canvas API, that re-encoding does not carry EXIF fields through: the compressed output is built from pixel data, not from the original file’s metadata block. If EXIF preservation matters for a specific file, that is worth checking before relying on the compressed copy.

The 50–70% figure is not a marketing round number; it is the typical range seen across real batches run through the side panel, though results vary by file.