SUN to ICO Converter

Fast online SUN to ICO conversion for free

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Reliable Output

SUN data is accurately transformed into well-formed ICO output. The conversion engine handles the format differences automatically.

Quality Preserved

Your original SUN visual data transfers cleanly to ICO format. The converter maps pixel content accurately without unnecessary loss.

Simple Workflow

Three steps: upload SUN data, pick ICO, download the result. No technical knowledge required — Convertio handles everything.

How to convert SUN to ICO

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose ico or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your ico file right afterwards

About formats

SUN is a raster image format associated with Sun Microsystems workstations, encompassing both the Sun Raster format (.ras) and the Sun Icon format used for window system icons and cursors on SunOS and Solaris systems. Sun Raster files, identifiable by their 0x59a66a95 magic number, store bitmap images in 1-bit monochrome, 8-bit indexed color, 24-bit BGR, or 32-bit XBGR modes, with optional run-length encoding compression and a 32-byte header. The Sun Icon subset is a simpler text-based format used for small monochrome bitmaps — window icons, cursor images, and toolbar graphics — stored as C-language data arrays that could be directly compiled into X Window and SunView applications. These icon files begin with a comment block specifying width, height, and optionally hot spot coordinates (for cursor images), followed by hexadecimal pixel values in a format readable by both the C compiler and the iconedit tool. Sun workstations running SunOS and later Solaris were foundational platforms for Unix computing, networking, and the early internet, and the SUN image formats were integral to their graphical environments. One advantage is the format's dual text/binary nature: Sun Icons are valid C source code that can be #included directly into applications, a practical approach to resource embedding that predates modern asset management systems. The Sun Raster variant's simplicity provides another strength — the 32-byte header and straightforward encoding make it one of the easiest binary image formats to parse. SUN format files are supported by ImageMagick, GIMP, XnView, and Unix image viewing tools.
Developer: Sun Microsystems
Initial release: 1982
ICO is the icon file format for Microsoft Windows, introduced with Windows 1.0 in 1985 and serving as the standard container for application icons, file type icons, and shortcut icons throughout the Windows ecosystem. An ICO file bundles multiple image variants within a single container — each at different sizes (16x16, 32x32, 48x48, 256x256, and others) and color depths (4-bit, 8-bit, 24-bit, 32-bit with alpha) — allowing Windows to select the most appropriate image for each display context, from tiny taskbar buttons to large desktop icons. The container structure consists of an ICONDIR header, an array of ICONDIRENTRY records describing each variant, and the image data itself. Since Windows Vista, ICO files support embedded PNG-compressed images for the larger sizes (typically 256x256), dramatically reducing file size while maintaining quality with full alpha transparency. One advantage is automatic size adaptation — Windows pulls the optimal resolution from the ICO container for each context (Explorer list view, desktop tile, Alt-Tab preview), ensuring crisp display without the application managing separate image files. The format's operating system-level integration is another core strength: ICO files serve as the identity mechanism for executables, file associations, and shortcuts across all Windows versions, and web browsers use favicon.ico for website identity in tabs and bookmarks. ICO creation and editing is supported by image editors like GIMP, Inkscape, and dedicated icon tools, and the format remains essential for Windows application development.
Developer: Microsoft
Initial release: 1985

Frequently Asked Questions

Why convert SUN to ICO?

SUN is a legacy format from Sun Microsystems workstations, rarely supported today. ICO conversion makes the image usable in modern tools.

What programs open ICO files?

ICO files can be opened in Windows Explorer natively, web browsers as favicons, IrfanView, GIMP, and icon editing tools.

Does converting SUN to ICO lose quality?

The conversion preserves the visual content of your SUN data accurately. Any differences depend on ICO's format characteristics like compression type.

Is SUN to ICO conversion free?

Standard conversions are free on Convertio. Premium plans unlock larger uploads, faster processing, and higher-volume batch conversions.

What makes ICO a good target format?

ICO offers multi-resolution, Windows UI standard, favicon support. It gives your raw SUN data a proper structure that any image viewer or editor can handle.