DocBook to SUN Converter
FileFlip converts DocBook to SUN entirely inside your browser, using Pandoc, MuPDF and ImageMagick compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert a DocBook file to SUN?#
- Drop your DocBook file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to SUN and the conversion starts on its own. FileFlip downloads 79.9 MB of WebAssembly the first time and nothing after that, then runs Pandoc, MuPDF and ImageMagick on your own machine.
- Save the SUN file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting DocBook to SUN lose quality?#
Yes, in the sense that text stops being text. Each DocBook page is rendered to pixels and handed to SUN, so the result looks right and can no longer be selected, searched, or reflowed.
Is it safe to convert DocBook files online?#
Yes, because nothing is uploaded. FileFlip converts DocBook files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What DocBook to SUN actually does to the file#
Converting DocBook to SUN runs on Pandoc, MuPDF and ImageMagick, downloads 79.9 MB of WebAssembly the first time and nothing after that, renders each page to pixels, keeps page layout, and drops selectable text and transparency.
| Engine | Pandoc, MuPDF and ImageMagick |
|---|---|
| Conversion path | 3 steps: DocBook → HTML → PNG → SUN |
| Downloaded to your browser | 79.9 MB, once, then cached by your browser |
| Quality | Text becomes pixels |
| You get back | One image per page, zipped when the source has several |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Selectable text | Dropped | The target format has nowhere to put it. |
| Page layout | Kept | Carried through into the converted file. |
| Transparency | Dropped | The target format has nowhere to put it. |
Worth knowing before you start:
- pages render at twice their point size in opaque RGB, roughly 144 DPI, with no transparency
- reflowable input is laid out on a fixed 595x842pt page at 11pt before anything else happens
- the file passes through HTML on the way, so anything HTML cannot express does not survive
What is a DocBook file?#
A DBK file is a DocBook document, XML markup that describes a technical document's structure and meaning, such as chapters, sections, and code listings, rather than its visual layout, so one source can be styled into a printed book or a web page.
Write in DocBook when producing technical documentation that has to publish to multiple outputs, such as print, web, and help, from one validated source.
Convert DocBook to another format when the reader only needs the finished document and doesn't need to maintain the structured XML source.
What is a SUN file?#
A SUN file is a Sun Raster bitmap, the same raw framebuffer image format Sun Microsystems shipped on SunOS workstations, saved under the alternate .sun extension some raster-image tools use in place of the identical .ras.
Recognise a .sun file as a Sun Raster image if it turns up alongside .ras files from the same legacy Solaris export or archive.
Convert SUN to PNG or TIFF for any modern use, since the .sun extension gets even less software recognition than .ras.
DocBook to SUN questions people ask#
What opens a .dbk file?
A .dbk file is DocBook XML, which is plain text, so any text or XML editor opens it, though tools like Oxygen XML Editor or Visual Studio Code with an XML extension add validation and structure awareness. Converting it to HTML or PDF is the usual way to read it as a finished document.
Why is DocBook so much more verbose than Markdown?
DocBook tags every structural piece of a document explicitly, such as marking a term as a <function> or a note as a <warning>, instead of relying on plain punctuation the way Markdown does. That verbosity is deliberate: it's what lets the same source publish correctly to print, web, and help formats without rewriting it for each one.
Is DocBook still actively maintained?
DocBook is still usable and its tooling still works, but the OASIS technical committee that governed the specification closed in September 2024. Development now happens informally rather than through that standards body, which is typical of a format that has settled rather than one still evolving quickly.
What is a SUN file?
A SUN file is a Sun Raster bitmap, the simple framebuffer image format Sun Microsystems used on SunOS and Solaris workstations, identified by a fixed magic number at the start of the file rather than by its extension.