What is the RIFF file format?
.riff is the native raster image format of Corel Painter, a digital painting application originally created by Fractal Design Corporation in 1991. The format is also saved with the three-character alias .rif, a legacy DOS filename convention - both extensions open identically in Painter.
Despite its name, Corel Painter's RIFF format is entirely unrelated to Microsoft's Resource Interchange File Format (also abbreviated RIFF), which is the container used by .WAV audio and AVI video. The two share only an acronym; their binary structures are completely different.
.riff files store raster image data in a block-structured binary layout with big-endian byte order, and support full preservation of Painter-native layer types - watercolor layers, liquid ink, impasto, and dynamic layers - that cannot survive export to .PSD or .TIF, where they are flattened or lost.
The format supports up to 32 bits per pixel (8 bits per RGBA channel), with floating-point channel support in newer versions of Painter. Canvas size is constrained only by available system RAM. Because each major Painter release may introduce new block types, .riff files from newer versions may not fully open in significantly older versions of the software.
.riff is the only format that preserves the complete feature set of Corel Painter canvases. Corel Painter 2024 is the current release.
Security & safety
RISK: LOWRIFF is a passive raster image format; no macro or script execution. Risk limited to malformed files causing application crash.
Format details
in a nutshell- Microsoft RIFF container - Microsoft's 'Resource Interchange File Format' uses .rmi/.riff in rare contexts; the WAV/AVI family uses RIFF headers internally but not the .riff extension - still, the same letters cause search confusion.
Programs that open RIFF files
Windows2 apps
macOS1 app
Technical details
deep spec| File encoding | Binary (proprietary Corel Painter block structure) |
| Byte order | Big-endian (unlike Microsoft RIFF which is little-endian) |
| Compression | Run-length encoding (RLE) or uncompressed; a compression indicator flag is stored in the file header |
| Color depth | Up to 32 bpp (8 bits per RGBA channel); floating-point channels supported in newer Painter versions |
| Layer types | Preserves all Painter-native layers: watercolor, liquid ink, impasto, and dynamic layers - lost or flattened when exporting to PSD or TIFF |
| Canvas size limit | No hardcoded pixel limit; constrained only by available system RAM |
| Typical file size | 500 KB - 500 MB depending on canvas dimensions and layer count |
| File header | Starts with two zero bytes followed by size and dimension fields; NOT the same as Microsoft RIFF (which starts with 52 49 46 46 / 'RIFF') |
| Naming conflict | Name 'RIFF' conflicts with Microsoft's Resource Interchange File Format used by WAV and AVI - completely different binary specification |
| DOS alias | .rif is the 3-character legacy DOS alias for the same format; both extensions open identically in Corel Painter |
| Format history | Introduced with Fractal Design Painter 1.0 in 1991; Corel acquired the software in 1999 |
| Supported platforms | Windows and macOS |
| Released | 1991 (Fractal Design Painter 1.0) |
| Latest version | Painter 2024 (2023); internal version evolves with each Painter release |
| Specification | www.painterartist.com |
RIFF conversions
Community Q&A
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