TCR to SUN Converter

Free TCR to SUN raster image conversion online

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Two Legacy Formats United

Bridge the gap between TCR compressed PalmOS text and SUN raster images — both legacy formats serving distinct historical platforms.

Cloud Conversion Engine

Convertio handles all heavy lifting on remote servers. Upload your TCR, receive a SUN image — no local software or plugins needed.

Any Platform Works

Access Convertio from Windows, macOS, Linux, or mobile. Your TCR to SUN conversion runs in the browser regardless of operating system.

How to convert TCR to SUN

1

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

2

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

3

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

About formats

TCR (Text Compression for Reader) is a compressed plain-text ebook format developed by Barry Childress in the early 1990s for the Psion Series 3 family of palmtop computers. The format was created for Childress's Reader3 application, a text file viewer that needed to fit large books into the Psion's extremely limited storage — typically 128 KB to 2 MB of available memory. TCR uses a dictionary-based compression scheme derived from the earlier ZVR format by Ian Giddings, replacing repeated byte sequences with single-byte tokens that reference a header dictionary. This straightforward approach achieves compression ratios of roughly 40-60% on typical English prose while requiring minimal CPU resources for decompression. The Psion Series 3 ran on a 3.84 MHz NEC V30 processor with no floating-point unit, so TCR's low computational overhead was essential for smooth page-by-page reading. A key advantage is remarkable storage efficiency for its simplicity — users could carry dozens of novels on removable SSD cards that held only a few hundred kilobytes. The format found a dedicated user community among Psion enthusiasts who built libraries of compressed literature for portable reading years before smartphones existed. Though the Psion platform faded from the market in the early 2000s, TCR files can still be opened and converted by modern ebook tools, and the format stands as an early example of purpose-built mobile reading technology from the pre-smartphone era.
Developer: Barry Childress
Initial release: 1993
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

Frequently Asked Questions

Why convert TCR to SUN?

SUN raster images are used in legacy Solaris and SunOS environments. This conversion renders your TCR text as a graphic for those platforms.

How do I view SUN files?

GIMP, ImageMagick, XnView, and IrfanView all support Sun Raster format. Native Sun/Solaris graphics tools handle SUN files directly.

Is SUN the same as RAS?

Essentially yes — SUN and RAS both refer to the Sun Raster image format. The extension differs, but the underlying format is the same.

Does the conversion preserve all text?

All text from the TCR file is rendered into the raster image. Note that it becomes pixel data — not selectable or editable text.

Is this conversion free on Convertio?

Yes, TCR to SUN conversion is available at no charge. Paid plans offer batch uploads and higher processing priority.