BMP vs DDS flight sim textures explained: compare compression, mipmaps, alpha channels, compatibility and the safest way to convert files.
Across Microsoft Flight Simulator, Prepar3D and X-Plane add-ons, BMP and DDS are texture containers, not measures of quality. BMP is common in older packages and may be uncompressed or use simulator-specific DXT compression; DDS is built to store GPU-ready compression and mipmaps. Use the exact format, alpha channel and orientation the target simulator expects.
What actually differs between BMP and DDS textures?
BMP and DDS differ mainly in how texture data and metadata are packaged, not in the artwork they can display. The extension alone does not reveal the image quality or even guarantee that compression is being used.
| Aspect | BMP | DDS |
|---|---|---|
| File structure | Either an ordinary Windows bitmap or a simulator-specific extended bitmap | DirectDraw Surface container designed for graphics textures |
| Compression | Often uncompressed, although extended flight-sim BMP files can contain DXT compression | Commonly uses DXT or BC compression, but can also be uncompressed |
| Mipmaps | Ordinary BMP files do not contain a mip chain; extended simulator BMP files may | Natively stores multiple mip levels in one file |
| Alpha channel | Possible in 32-bit and extended formats, with support dependent on the simulator and editing tool | Explicitly supported by suitable DDS pixel formats |
| Typical use | Legacy Microsoft Flight Simulator aircraft, panels and scenery | FSX, Prepar3D, modern Microsoft Flight Simulator packages and many X-Plane projects |
Many flight-sim BMP textures are not ordinary paint-program bitmaps. Opening one and saving it from a generic editor can remove its alpha channel, compression or mipmaps even though the file still ends in .bmp. Our guide to inspecting and converting textures with DXTbmp explains how to preserve those elements.
A mistake we see constantly is treating DDS as automatically newer, faster and better. An uncompressed BMP can be much larger than a compressed DDS, but a DXT-compressed extended BMP and a DDS using the same compression can have similar storage and visual characteristics.
Which texture format should I use for a flight sim add-on?
Use the format expected by the simulator, material definition and original add-on rather than converting every texture to DDS.
- FS2004 and older Microsoft simulators: Retain the supplied BMP format unless the aircraft or scenery documentation specifies another workflow. Legacy extended BMP files often contain data that an ordinary image editor cannot preserve.
- FSX and Prepar3D: DDS is common for aircraft and scenery, but legacy BMP textures remain valid in many packages. Different assets inside one add-on may use different formats; this FSX aircraft package containing both BMP and DDS files is a practical example.
- Microsoft Flight Simulator 2020 and 2024: Use the simulator's package-building workflow and material definitions. Runtime textures are generally compiled to DDS, but converting an old FSX BMP by itself does not create a compatible modern material.
- X-Plane: Follow the aircraft or scenery project's established PNG/DDS workflow. Do not apply Microsoft Flight Simulator orientation or alpha assumptions automatically.
DDS is most useful when the target supports its compression and mipmaps directly. It can reduce storage and graphics-memory use compared with an uncompressed BMP, while a correct mip chain reduces distant shimmering. Visual quality still depends on resolution, compression type, source artwork and how the material interprets each channel.
Can I convert a BMP texture to DDS by renaming it?
No; changing .bmp to .dds does not convert the binary data and normally leaves the simulator unable to read the texture.
- Back up the complete texture folder. Keep the original files and their names together so that you can restore the package.
- Identify the texture's role. Diffuse, night, normal, specular and reflection maps can use different channel layouts. An alpha channel does not always mean transparency.
- Inspect the original. Record its dimensions, alpha channel, compression, mipmaps and orientation before editing.
- Export to the required DDS format. Match the add-on's existing compression and alpha treatment. DXT1 does not provide a smooth full alpha channel, while DXT3 and DXT5 do; modern materials may require other BC formats or packed channels.
- Generate mipmaps only where expected. Missing mipmaps can cause shimmering, while badly generated ones make markings and lettering turn muddy too soon.
- Test close up and at a distance. Check daylight, night lighting, transparency and reflections. For aircraft paint specifically, follow a livery workflow that preserves the simulator's required texture format.
Avoid repeatedly converting between compressed BMP and DDS files. DXT and BC compression are lossy, so each recompression can add block artefacts around lettering, rivets and high-contrast colour boundaries.
Why does a converted DDS texture look wrong?
Most failed conversions come from lost alpha data, incorrect vertical orientation, unsuitable compression or broken mipmaps rather than from DDS itself.
- The texture is invisible, excessively transparent or too reflective: The alpha channel was removed, inverted or assigned the wrong meaning. In some materials it controls reflection or another effect rather than opacity.
- The texture is upside down: Some FSX-era DDS export workflows use a vertical orientation different from the equivalent BMP workflow. Preserve the orientation expected by the particular converter and simulator.
- Markings blur too early: Inspect the generated mip levels. Automatic filters can erase thin registration letters, stripes and panel details.
- The surface shimmers in the distance: The file may lack a complete mip chain, or the simulator may not be recognising it.
- Colours show square blocks or halos: The chosen compression is too aggressive for the artwork, especially around sharp text and alpha edges.
- The simulator still shows the old texture: A BMP and DDS with the same base name may coexist, and simulator lookup rules or cached package data can select the other file. Do not rely on extension priority; remove duplicates only after making a backup.
- The texture does not load: The DDS may use a pixel format unsupported by that simulator or material. Match a working texture from the same add-on rather than choosing a format by file size alone.