HOW IT WORKS

From almost any major still-image source to complete responsive output sets.

1. Choose or drop source images

Select one image or a batch. Supported inputs are JPG/JPEG/JFIF, PNG, WebP, AVIF, HEIC/HEIF, TIFF/TIF, GIF, BMP, SVG and ICO.

2. AutoWebP detects each source format

The engine identifies the file format from its MIME type and extension, then chooses a browser-native decoder or a local-running fallback decoder where required.

3. Native decoding is the fast path

When a browser already decodes a source format correctly, AutoWebP uses that native capability. This normally covers common formats such as JPEG, PNG, WebP, GIF, SVG, BMP and ICO and may cover AVIF on modern browsers.

4. Source orientation is normalized before resizing

For supported JPEG and TIFF files, AutoWebP reads the source-orientation value locally and resolves rotation or mirroring before responsive dimensions are calculated and output files are encoded. The generated image therefore uses the correctly oriented pixel geometry rather than relying on display metadata after conversion.

6. AVIF fallback decoding and encoding

If native AVIF support is insufficient, AutoWebP can load a pinned WebAssembly AVIF codec and run it locally. AVIF output therefore no longer depends solely on canvas.toBlob('image/avif').

6. HEIC / HEIF input

For HEIC/HEIF files, AutoWebP can use a browser-compatible libheif decoder locally. The decoded pixels then enter the same resizing and output pipeline as other source formats.

7. TIFF input and output

TIFF files can use a local TIFF decoder where native support is unavailable. TIFF output can also be generated from the resized pixel data.

8. Choose one or multiple outputs

Select WebP, AVIF, JPEG, PNG, still-frame GIF, TIFF, BMP or ICO. WebP and AVIF can be generated together for modern responsive websites while JPEG or PNG can be added as broad fallback formats.

9. Choose quality

WebP, AVIF and JPEG have independent quality controls because their encoders do not interpret quality identically. PNG remains lossless-style output. TIFF and BMP outputs are not presented as compressed web alternatives.

10. Transparency handling

Formats that support alpha can preserve transparent pixels. JPEG and BMP require transparent pixels to be flattened onto a selected background colour.

11. Select responsive widths

Use the built-in 320, 480, 640, 768, 1024, 1280, 1536, 1920 and 2560 pixel presets or enter custom widths. The original Omega core widths of 320, 768 and 1536 remain included.

12. No responsive upscaling

A responsive width is generated only when it is smaller than the source width. This prevents AutoWebP from fabricating additional detail by enlarging a smaller source.

13. Progressive high-quality downscaling

Large reductions can be performed through multiple intermediate steps before the final size, using high-quality canvas smoothing for cleaner edges and better visual retention.

14. Full-size re-encoded copy

When enabled, AutoWebP also creates a re-encoded version at the original pixel dimensions for each selected output format that supports the source size. ICO output is limited to icon-appropriate dimensions up to 256 pixels.

15. Batch processing

Every selected source is processed against the selected widths and formats automatically. The progress display reflects the complete number of generation jobs.

16. Duplicate detection

Files with matching sizes can be compared using local SHA-256 hashes to identify exact duplicates before processing. The source files themselves are not deleted.

17. Individual downloads and ZIP export

Generated files remain available individually, and AutoWebP contains its own browser-side ZIP writer so the complete set can be packaged without uploading files to a ZIP service.

18. Responsive picture markup

For the first processed source, AutoWebP can produce a <picture> template containing AVIF, WebP, JPEG and PNG srcset sources that correspond to the generated files.

19. Local-first does not mean no network requests at all

The user's image pixels are processed locally. The website, PWA resources and additional codec modules must still be delivered to the browser. If a required codec is not already cached, its program code may be downloaded from the pinned codec provider before local execution.

20. PWA caching

The service worker caches the application shell and attempts to cache the pinned codec entry points. After successful caching, the PWA can reuse those resources. Browser storage eviction, clearing site data or changing browser/device may require them to be downloaded again.

21. Animated and specialised formats

AutoWebP is a still-image responsive production engine. Animated GIF or animated AVIF content is not promised to retain animation; the current workflow processes a still frame. Camera RAW, layered design files, scientific imagery and proprietary formats outside the stated input list are not claimed as supported.