ICO vs NEF
A detailed comparison of ICO Icon and Nikon RAW NEF — file size, quality, compatibility, and which format to choose for your workflow.
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Technical Specifications
| Specification | .ICO | .NEF |
|---|---|---|
| MIME type | image/vnd.microsoft.icon | image/x-nikon-nef |
| 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+) | Uncompressed, Lossless, Lossy Compressed |
| Extension | — | .nef (full) / .nrw (Coolpix variant) |
| Container | — | TIFF/EP with Nikon MakerNote tags |
| Bit depth | — | 12 or 14-bit (body-dependent) |
Strengths 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.
.NEF Strengths
- Deep metadata — Active D-Lighting, Picture Control, lens profile all preserved.
- Backward-compatible since 1999.
- Supported by every major raw processor (Lightroom, Capture One, DxO, Darktable).
- Embedded full-size JPEG preview.
- Lossless or moderately compressed variants available.
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.
.NEF — Limitations
- Proprietary — no official spec.
- Some Nikon makernote features don't round-trip through third-party tools.
- File sizes are large (20-60 MB typical).
- The 2005 encryption episode damaged trust in the format.
.ICO ICO Icon
ICO 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.
The ICO file was born on November 20, 1985, the day Microsoft shipped Windows 1.0. Every application icon, every folder glyph, every cursor needed a container, and Microsoft designed .ico as a raw-pixel, multi-resolution bundle: one file holds multiple sizes (16×16, 32×32, 48×48, 256×256) and the OS picks the best one for the current context. For 15 years ICO was a Windows-only curiosity. Then in 1999 Microsoft quietly slipped a line into Internet Explorer 5: if a site hosts /favicon.ico, the browser will display it in the tab and bookmarks. Overnight every webmaster on Earth needed one. That single convention turned .ico into the most widely requested image file type on the internet — every browser, every day, checks every domain for it.
.NEF Nikon RAW NEF
NEF is Nikon camera RAW format with full sensor data and camera metadata.
NEF — Nikon Electronic Format — shipped in 1999 with the Nikon D1, the first professional digital SLR to cost less than $6,000 and be taken seriously by newspaper wire services. For 25+ years every Nikon DSLR and mirrorless has written NEF as its raw format. The container structure is a TIFF variant (like CR2) with Nikon’s own makernotes IFD carrying lens data, white balance presets, Active D-Lighting settings, and Picture Controls. NEF has been controversial. In 2005 Nikon encrypted the white-balance metadata in its D2X files to discourage third-party converters, triggering an open letter from Adobe CEO Bruce Chizen. Nikon eventually backed down after community backlash. Today NEF remains the native raw format for every new Nikon body, and the largest single source of RAW files in professional news and sports photography.
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.
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