RGF File Format (.rgf)
An RGF file is a tiny black-and-white bitmap, capped at 255 by 255 pixels, that LEGO Mindstorms EV3 robots use to show an icon or image on the brick's built-in screen.
RGF at a glance#
| Full name | LEGO Mindstorms EV3 Robot Graphic Format (black and white) |
|---|---|
| File extension | .rgf |
| Category | Image Files |
| Developer | LEGO |
| Compression | Uncompressed |
| FileFlip support | FileFlip does not handle this format |
Strengths and limitations of RGF#
What RGF does well
- A two-byte header plus packed bits keeps even a full 255 by 255 icon under a few kilobytes
- Simple enough that the EV3 brick's limited firmware can decode it without a general image library
- Every known decoder, from the EV3 firmware to ImageMagick to community tools, agrees on the same structure
Where RGF falls short
- Fixed two-colour, black-and-white palette with no greyscale or colour
- Maximum dimensions of 255 by 255 pixels, since width and height are each stored in a single byte
- No official LEGO specification has been published, so support outside ImageMagick and a few community EV3 tools is essentially nonexistent
Use RGF only when preparing an icon or image to display on a LEGO Mindstorms EV3 brick's screen, the one context that actually reads the format.
Convert RGF to PNG or BMP for editing or viewing on a computer, since general image software has no reason to support a format built for one robot's small screen.
How to open a .rgf file#
A .rgf file opens in the programs below, grouped by the platform you are on.
| Platform | Programs that open it |
|---|---|
| Windows | ImageMagick |
| macOS | ImageMagick |
| Linux | ImageMagick |
| Web | FileFlip |
RGF questions people ask#
What is an RGF file?
An RGF file is a small black-and-white bitmap used by LEGO Mindstorms EV3 robots to display icons and images on the brick's screen. No official LEGO specification for the format has been published, so what's known about its structure comes from tools that decode it, such as ImageMagick.
What software opens RGF files?
ImageMagick reads and writes RGF files directly, and a small number of community LEGO Mindstorms EV3 tools support the format for building brick icons. Mainstream image viewers and editors generally do not recognise it.
How big can an RGF image be?
An RGF image is limited to 255 by 255 pixels, because the file's header stores width and height as a single byte each. That ceiling matches the small screen on the LEGO Mindstorms EV3 brick the format was built for.
Converting RGF files#
FileFlip cannot open a .rgf file, so there is nothing to convert it into here. It appears on the site as something other formats can be converted to.
FileFlip does not write .rgf files, so nothing on the site converts into this format. It works as a source only.
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.