WebP and AVIF are raster image formats that can reduce transferred file sizes at suitable quality. Joomla sites can use them for photographs and other graphics when the processing and display environment supports them.
Format considerations
Both formats support transparency and different compression modes. Size depends on the image, encoding settings and acceptable distortion. AVIF can perform well for photographs, but encoding cost and size savings should be measured on actual files.
Renaming an extension does not convert an image. Real export or encoding is required. Text, diagrams and logos may benefit from other formats, including SVG.
Joomla workflows
In Joomla, check uploading, thumbnail generation and extension processing. Browser support does not mean the installed server library can create the format.
For Joomla images, dimensions, quality, alt text and aspect ratios also matter. The picture element can offer formats and a fallback, while srcset provides resolution variants. Check details, colour and transparency after conversion.
Conclusion
WebP and AVIF are useful when quality and compatibility are considered. Optimisation includes dimensions, delivery and visual checks as well as format choice.