ICO vs RW2
A detailed comparison of ICO Icon and Panasonic RAW RW2 — file size, quality, compatibility, and which format to choose for your workflow.
ICO Icon
Raster & Vector ImagesICO is the icon file format used for favicons and Windows application icons. A single ICO file can contain multiple image sizes and color depths for different display contexts.
About ICO filesStrengths Comparison
ICO Strengths
- Multi-resolution: one file, many sizes, OS picks the right one.
- Universal favicon support in every browser since IE5.
- Supports transparency (1-bit since 1985, full alpha since XP).
- Tiny file size — an entire favicon pack typically fits in under 15 KB.
- No licensing or patent concerns — fully in the public domain spec-wise.
RW2 Strengths
- Compact thanks to Micro Four Thirds sensor size.
- Hybrid photo/video workflow friendly on GH bodies.
- Supports 14-bit depth on Lumix S.
- Stable format since 2008.
Limitations
ICO Limitations
- Cannot compress continuous-tone images efficiently — use PNG or WebP for photos.
- Format is essentially frozen in 1999 — no HDR, no wide gamut, no modern features.
- Maximum image dimension is 256×256 px (inside an ICO container).
- Editing requires specialized tools — most image editors treat it as a curiosity.
RW2 Limitations
- Proprietary — no public spec.
- Market share is niche; fewer tutorials.
- MFT sensor means less dynamic range than full-frame.
- Video-focused bodies mean some RW2 files are actually video-extracted frames with different artifacts.
Technical Specifications
| Specification | ICO | RW2 |
|---|---|---|
| MIME type | image/vnd.microsoft.icon | image/x-panasonic-rw2 |
| Max resolutions per file | 65 535 images | — |
| Max single image size | 256×256 px | — |
| Color depths | 1, 4, 8, 24, 32 bits per pixel | — |
| Compression | Uncompressed bitmap or embedded PNG (Vista+) | — |
| Extension | — | .rw2 |
| Container | — | TIFF/EP variant with Panasonic MakerNote |
| Bit depth | — | 12 or 14-bit |
| Related | — | .raw (older Panasonic bodies) |
Typical File Sizes
ICO
- Classic favicon (16×16 only) < 2 KB
- Multi-size favicon pack (16/32/48/256) 5-15 KB
- Full Windows app icon set 20-100 KB
RW2
- 20 MP RW2 (G9, GH5) 20-25 MB
- 47 MP RW2 (Lumix S1R) 50-75 MB
Ready to convert?
Convert between ICO and RW2 online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
ICO (Icon) is Microsoft's 1985 multi-resolution icon format, originally shipped with Windows 1.0. A single .ico file holds multiple sizes (16×16, 32×32, 48×48, 256×256) so the OS can pick the best one for the current display context. Since 1999, every website uses a favicon.ico to show its icon in browser tabs.
On Windows, ICO files open natively in File Explorer and Photos. On macOS, Preview handles basic display. For editing, use GIMP (free), Photoshop with a plugin, or dedicated icon editors like IcoFX.
Use the PNG-to-ICO converter on KaijuConverter — upload a PNG (ideally square, at least 256×256) and download a multi-resolution ICO with all standard favicon sizes embedded.
A complete favicon pack includes 16×16, 32×32, 48×48, and 256×256 px variants all in one ICO file. The total file size is typically 5-15 KB. Browsers automatically pick the right size for tabs, bookmarks, and desktop shortcuts.
ICO for /favicon.ico (every browser requests this URL automatically). PNG for everywhere else — social media profile images, in-page icons, app logos. Modern favicon best practice includes both an .ico at the root and multiple .png sizes referenced via <link> tags in HTML.
Yes. Every browser still requests /favicon.ico on every domain as its first icon fallback. Modern sites typically provide both favicon.ico and higher-quality SVG or PNG icons via <link rel="icon"> tags — browsers pick the best match.