Image Format Checker
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Image Format Checker: See Which Formats Your Images Use
Image format affects file size and visual quality. This checker finds images on a page and reports their formats.
Common Formats
- JPEG: good for photographs, with lossy compression that reduces size at some cost to quality.
- PNG: lossless and supports transparency, but often larger than JPEG for photos.
- GIF: limited to 256 colors, suitable for simple graphics and animations.
- WebP: supports both lossy and lossless compression and transparency, often smaller than JPEG or PNG at similar quality.
- AVIF: a newer format with strong compression, gaining support in modern browsers.
- SVG: vector format for logos, icons, and illustrations, scalable without quality loss.
Why Format Choice Matters
- File size: modern formats can significantly reduce bytes compared with older ones.
- Quality: choosing the wrong format can cause visible artifacts or unnecessarily large files.
- Transparency: only some formats support it, which matters for logos and overlays.
- Loading speed: smaller images load faster, improving page performance.
What to Look For
- Photographs still served as PNG or BMP, where JPEG or WebP would be smaller.
- Logos and icons served as raster images when SVG would be sharper and smaller.
- Older formats used where WebP or AVIF support is available.
- Inconsistency across a page, with some images optimized and others not.
Practical Uses
- Auditing a page for image optimization opportunities.
- Reviewing a gallery or product listing.
- Checking a site before a performance-focused redesign.
- Comparing formats used across similar pages.
Limitations
The checker reports the formats in use. It does not measure the actual file sizes or compare visual quality. Full optimization requires checking dimensions, compression settings, and delivery options such as responsive images.
Summary
Image format influences file size and quality. This checker lists the formats on a page, helping you spot opportunities to switch to more efficient modern formats.
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