Reference Formats
ICO
A lossless Windows container bundling the same icon at multiple resolutions and color depths into one file, used for application icons and browser favicons, with no metadata capacity.
Extension
.ico
Full name
Windows Icon (Icon Image File)
Introduced
1985 (Windows 1.0, monochrome icons); modern multi-image structure with Windows 3.0, 1990
Vendor
Microsoft Corporation
What is inside the container
ICO stores multiple images of the same icon — from 16x16 up to 256x256 pixels, 1-bit monochrome up to 32-bit RGBA — as either raw uncompressed bitmap data or, since Windows Vista, embedded PNG-compressed frames for larger sizes, letting the OS pick the best match for context. It carries no meaningful metadata: ExifTool can only read ICO files, with no write capability for EXIF, IPTC, XMP, or ICC profiles.
How to open it
For archives
Do not use ICO as a DAM master format. It is a derived, presentation-only container (icons, favicons) with no metadata capacity and no color-management support. Keep the source artwork (SVG, PNG, or PSD) as the DAM master and generate ICO on demand as a final packaging step for app or web delivery.
ICO dates back to Windows 1.0 in 1985 as a simple monochrome icon format, but the multi-image structure recognizable today — bundling several resolutions and color depths of the same icon into one ICONDIR-based file — arrived with Windows 3.0 in 1990. The whole point of packing multiple sizes into a single file is so the OS can pick whichever resolution best fits the display context (taskbar, desktop, Explorer thumbnail) without scaling artifacts.
ICO exists to solve OS icon presentation, not image interchange or archival, and that shows clearly in a DAM context: it carries no EXIF, IPTC, or XMP at all, and ExifTool can only read ICO files — there’s no metadata write path even if a DAM wanted to inject search-relevant fields. ICO assets are almost always end-of-pipeline exports (favicons, installer icons, app icons) rather than searchable creative assets in their own right.
Because there’s no embedded metadata to index, a DAM managing ICO files has to rely entirely on filename conventions or a linked parent-asset record (the source logo or icon artwork the ICO was generated from) for search and organization. The practical workflow is to keep the true master — an SVG or high-resolution PNG/PSD — as the DAM asset, and treat any ICO file as a generated packaging output rather than something to catalog independently.
Frequently asked
Should a DAM use ICO as a master format?
No. ICO is a derived, presentation-only container for icons and favicons with no metadata capacity and no color-management support. Keep the source artwork (SVG, PNG, or PSD) as the DAM master and generate ICO on demand as a packaging step.
Does ICO support embedded metadata?
No — it carries no EXIF, IPTC, or XMP at all. ExifTool can only read ICO files, with no write capability, so there's no metadata path even if a DAM wanted to inject search-relevant fields.
How does a DAM search or organize ICO assets?
Entirely through filename conventions or a linked parent-asset record — typically the source logo or icon artwork the ICO was generated from — since there's no embedded metadata to index.
What does an ICO file actually contain?
Multiple images of the same icon at different resolutions, from 16x16 up to 256x256 pixels, and color depths from 1-bit monochrome up to 32-bit RGBA, stored as raw bitmap data or, since Windows Vista, embedded PNG-compressed frames.
Why does ICO bundle several sizes into one file?
So the operating system can pick whichever resolution best fits the display context — taskbar, desktop, Explorer thumbnail — without scaling artifacts.
Is ICO widely compatible across platforms?
Yes — it's Microsoft's native format for app icons in Windows File Explorer, the universal standard favicon format in every browser, and GIMP reads and writes it natively.
Where does ICO typically fit in a DAM workflow?
As an end-of-pipeline export — favicons, installer icons, app icons — generated from a source asset, rather than as a searchable creative asset in its own right.
When did the modern multi-image ICO structure appear?
ICO dates to Windows 1.0 in 1985 with simple monochrome icons, but the recognizable multi-resolution ICONDIR structure used today arrived with Windows 3.0 in 1990.
Sources
- ICO originated with Windows 1.0 (1985); the modern multi-image ICONDIR structure came with Windows 3.0 (1990), and later versions embed PNG-compressed frames. checked 2026-08-07 — Wikipedia: ICO (file format)
- ExifTool supports ICO as read-only, with no metadata write capability. checked 2026-08-07 — ExifTool supported file types
- GIMP supports reading and writing ICO Windows icon files. checked 2026-08-07 — Wikipedia: GIMP