What is the LUT file format?
.lut files store color look-up tables - mapping structures that translate input color values to specified output color values, used in image processing, color grading, and display calibration. A 1D LUT applies a separate tone curve to each color channel independently; a 3D LUT maps any input RGB triplet to an output RGB triplet via a three-dimensional sampling grid, enabling complex color-space transforms and film-emulation effects.
The .lut extension has no single universal format. XnView uses a proprietary binary .lut for palette and curve adjustments within its image viewer. Many professional tools - including DaVinci Resolve, Houdini, and Adobe Photoshop - treat .lut as a generic extension for plain-text ASCII tables of space-separated float values. Common 3D LUT grid sizes are 17×17×17, 33×33×33, and 65×65×65 nodes, with bit depths ranging from 10-bit and 12-bit (broadcast) to 32-bit float (VFX and HDR pipelines).
For professional color-grading interoperability, the Adobe CUBE format (.cube), published in 2013, has become the de facto standard and is more broadly supported than the generic .lut extension. Because .lut files may be either binary or plain text with no fixed file signature, the creating application must be known to interpret the data correctly. Related interchange formats include .3dl and .csp.
Security & safety
RISK: LOWLUT files are pure color-mapping data with no executable code. They pose no security risk. Installing a LUT from an untrusted source only affects color output - it cannot harm the system.
Format details
in a nutshell- Houdini LUT File - SideFX Houdini uses .lut for both 1D and 3D ASCII color lookup tables in its rendering pipeline.
- Generic 1D/3D LUT (broadcast/film) - Many broadcast and VFX applications export/import .lut as a generic extension for color grading tables; no single spec.
Programs that open LUT files
Windows3 apps
XnView
Freemium XnView loads .lut files automatically via Image > Film Simulation; place .lut in the AddOn/clut folder. 
DaVinci Resolve
Freemium Project Settings > Color Management > LUTs path, or drag LUT into the Color page nodes. 
macOS2 apps
DaVinci Resolve
Freemium Same as Windows: drag LUT into Color page or configure via Project Settings. 
Linux1 app
Technical details
deep spec| Encoding | Binary (XnView proprietary) or plain-text ASCII float values (generic tools); format varies by application |
| LUT types | 1D LUT (per-channel tone curve) and 3D LUT (full RGB-to-RGB mapping via sampling grid) |
| 1D LUT structure | One output value per input step per color channel (R, G, B curves) |
| 3D LUT structure | RGB output triplets at each node of an N×N×N sampling grid covering the full input color cube |
| Common grid sizes | 17×17×17, 33×33×33, and 65×65×65 nodes |
| Bit depth | 10-bit, 12-bit (broadcast); 32-bit float (VFX and HDR pipelines) |
| File signature | None - binary or text; format must be determined from the creating application |
| Typical size | Under 10 KB (1D LUT); hundreds of KB (3D LUT at 65×65×65 lattice) |
| Standardization | No universal `.lut` standard; Adobe CUBE (`.cube`, 2013) is the professional interoperability standard |
| XnView usage | Proprietary binary palette and color curve lookup for in-viewer image display adjustments |
| MIME type | `application/octet-stream` (binary variants) or `text/plain` (text variants) |
| Released | 1990s (LUT concept); XnView-specific .lut since early 2000s |
LUT conversions
Community Q&A
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