X3F to ICO Converter

How to Convert X3F to ICO Online

1. Upload Your X3F File: Drag and drop or click "+ Add Files" to add one or more .x3f raw files from a Sigma SD, DP, or Quattro/Merrill body. Batch is supported — drop a whole shoot.
2. Pick an Image Resolution Preset: ICO output is locked to icon-friendly sizes. The default is 256P (256×256), which Windows Vista+ uses for high-DPI shell icons. Drop to 128P, 64P, 48P, 32P, 24P, or 16P for taskbar, list-view, or legacy contexts. You'll typically run the conversion several times to produce a full set.
3. Adjust Quality, DPI, and Color Palette (Optional): The default render uses 300 DPI with a "Very High" quality preset. You can change the Image Quality Preset (Highest → Lowest), set Target file size as %, or target an exact KB/MB. For small icons, dropping the color palette to 16 / 32 / 64 / 128 / 256 colors keeps the ICO tiny without visible loss.
4. Convert and Download: Click Convert. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.

Why Convert X3F to ICO?

X3F is Sigma's proprietary raw format from Foveon-sensor cameras — the SD9 (2002) through the dp Quattro and sd Quattro lines (2014–2016, discontinued by 2025). Foveon stacks three photodiodes per photosite to capture R, G, and B at every pixel without a Bayer filter, so the data is unprocessed sensor output, not a viewable image. ICO is the Microsoft Windows icon container — a single file that bundles multiple BMP or PNG bitmaps at different sizes and color depths so Windows can pick the right one for any context.

• Turn a hero shot into a Windows shortcut icon — Use your best Foveon portrait, product, or logo capture as the custom icon for a desktop shortcut, an .exe, or a folder. The 256×256 preset is what Vista, 7, 8, 10, and 11 use for large icon views.
• Build a custom application icon — Developers shipping a Windows desktop app need an .ico embedded in the binary. Photographers and indie makers can promote a Foveon source straight to icon without round-tripping through Photoshop.
• Generate Windows shell icons — File Explorer renders 16×16 in list view, 32×32 in details, 48×48 in medium icons, 256×256 in extra-large. Producing the full set from a single high-quality raw avoids re-encoding banding from generation loss.
• Archive a Foveon shot in a shareable container — X3F requires Sigma Photo Pro (SPP) or a recent libraw build to open. Saving a small ICO render alongside the raw gives you a viewable thumbnail any Windows machine can preview without installing SPP.
• Salvage a legacy SD9 / SD10 capture — Older 2002–2004 X3F files from the original 2268×1512 Foveon sensor can be hard to open in modern editors. A quick conversion lets you reuse them as icons or favicons today.

X3F vs ICO — Format Comparison

ICO Size Quick Guide — Which Preset for Which Use

A full Windows-friendly .ico typically bundles 16, 32, 48, and 256 — produce each preset, then combine them with a tool that supports multi-image ICO output. Favicons in 2026 also commonly add separate 180×180 (Apple touch icon) and 192×192 / 512×512 (Android / PWA manifest) PNGs alongside the root favicon.ico; those live outside the ICO container.

Frequently Asked Questions

Why is the maximum ICO size only 256×256?

The ICO container, defined by Microsoft, caps each embedded image at 256×256 pixels. Anything larger has to live in a separate PNG referenced by your HTML or app manifest. That's why the XConvert resolution preset for ICO tops out at 256P and excludes 720p, 1080p, and higher options that are valid for JPG, PNG, or TIFF output.

Can one ICO hold multiple sizes at once?

Yes — that's the whole point of the format. A proper Windows icon bundles 16, 32, 48, and 256 (and optionally 24, 64, 128) inside one .ico so the OS can choose the closest match without scaling. This XConvert page produces a single-size ICO per run; export each size, then merge them in a tool like ImageMagick (convert 16.png 32.png 48.png 256.png app.ico) or a dedicated icon editor.

Will the Foveon color advantage survive the conversion?

Mostly no, and that's expected. Foveon captures full RGB per photosite, but ICO outputs at most 256×256 with 32-bit color. Downsampling that aggressively averages out any per-layer color resolution advantage. The Foveon source still helps for clean edges and noise-free detail at the small target size, but the icon won't visibly differ from one rendered out of a high-quality JPG or PNG of the same shot.

Should I render at 256 with high quality, or smaller for taskbar use?

Render at the size you'll actually use. Browsers and Windows scale ICO images poorly — a 256 forced down to 16 looks muddier than a 16 rendered directly. For favicons, ship both 16 and 32. For app icons, ship the full 16 / 32 / 48 / 256 quartet so the shell never has to scale.

Does the ICO support transparency from my X3F?

X3F doesn't carry an alpha channel — Foveon raws are pure sensor data, no transparency. If you need a transparent background on the icon, convert via X3F to PNG first, mask the background in an editor (Photopea, GIMP, Photoshop), then save the masked PNG into a 32-bit ICO. ICO has supported 8-bit alpha since Windows XP.

My X3F won't open in Photoshop directly — is that normal?

Yes, especially for older bodies. Adobe Camera Raw added X3F support unevenly across Sigma models; some SD-series and early DP files still need Sigma Photo Pro (SPP) or a recent libraw-based tool to demosaic. Browser converters that handle X3F (including XConvert) decode the embedded preview or run libraw under the hood, which is why the conversion works even when Photoshop refuses to open the source.

What's the difference between an .ico and a .png favicon?

favicon.ico is the legacy default — every browser since IE5 looks for /favicon.ico at the site root, and an ICO can hold both 16 and 32 in one file. Modern browsers also accept <link rel="icon" type="image/png" sizes="32x32" href="..."> pointing at standalone PNGs. The current best practice is to ship favicon.ico (16 + 32) as a fallback plus separate PNGs for 180×180 Apple touch and 192 / 512 for Android / PWA.

Can I batch-convert a folder of X3F files?

Yes. Drop in the whole folder; each file processes in parallel withon our servers and downloads individually or as a single ZIP. Use the same resolution preset across the batch, or set per-file if you need different icon sizes for different sources.

What if I want a non-icon output from X3F?

For full-resolution photographic output, use X3F to JPG, X3F to PNG, X3F to TIFF, or X3F to BMP. For the reverse direction — making an ICO from a PNG or JPG you already have — see PNG to ICO and JPG to ICO.