Roughness to Smoothness Converter for Unity (Invert Channel)
Unity's metallic workflow reads smoothness, most texture tools write roughness. Inverting is simple arithmetic, but only if the bytes survive: the Texture Lab reads the PNG itself, so the saved plane is exactly 255 − roughness.
- Channel PNGsMeasured· numpy
- Normal mapMeasured· numpy
- Packed mask / ORMMeasured· Pillow
- Engine importUNVERIFIED
What it does
- Channel invert that writes exactly 255 − v (checked with numpy on the downloaded file).
- Bytes under fully transparent texels kept, which a browser canvas would lose.
- Channel preview with its meaning in Unity HDRP (mask map) or URP (metallic + smoothness in alpha).
- Continue in the packer: smoothness goes into alpha of the URP metallic map or the HDRP mask map.
How to do it
- Drop the roughness map (PNG).
- Invert the channel.
- Download the smoothness map, or open the mask packer.
- Pack it with metallic (and AO for HDRP) using the Unity preset.
Outputs and how each was checked
"Measured" means the downloaded file was opened again outside the page (Pillow, numpy or an independent parser) and the property was measured. Loading these files in a game engine was not tested.
| Target | Files | Check |
|---|---|---|
| Channel PNGs | <name>-r/g/b/a.png (8-bit grey) | Measured numpyByte-identical per channel, including RGB under fully transparent texels. |
| Normal map | PNG · OpenGL (+Y) or DirectX (−Y) | Measured numpyDecoded vectors are unit length (worst deviation 0.0002); OpenGL and DirectX differ in green only. |
| Packed mask / ORM | Unity HDRP mask · URP metallic · ORM (glTF, Godot) | Measured PillowPacked bytes checked: ORM preset over AO 10 / roughness 80 / metallic 220 → (10, 80, 220, 255). |
| Engine import | Unity · Unreal · Godot | UNVERIFIEDNot imported in any engine. |
Evidence
Channel unpack byte-identical on all four channels (max difference 0), 2048 transparent texels keep their RGB; edge bleed changed 448 texels, all with alpha 0, and no alpha byte; OpenGL ↔ DirectX differ exactly in green (255 − g); converted normals decode to unit vectors.
Limits
- Exact channel bytes need PNG; JPEG/WebP are decoded by the browser and marked "not byte-exact".
- Interlaced PNG and 16-bit output are not supported; up to 33.5 million pixels on the exact path.
- A normal map's convention cannot be detected from its pixels, only converted.
- Nothing was imported into Unity, Unreal or Godot: channel orders rest on their documentation and engine source.
Questions
Which channel does Unity read smoothness from?
URP metallic: alpha of the metallic map. HDRP mask map: alpha too (R metallic, G AO, B detail mask). Both orders come from Unity's documentation, quoted in the Lab.
Was it imported into Unity?
No. The bytes were checked; import into Unity was not run here.
Is it free, and do I need an account?
Everything on these pages is free and works without an account. There is no watermark and no export that is held back.
Are my sprites uploaded?
No. The Studio decodes, packs and exports in this browser tab. Projects are autosaved in the browser (IndexedDB) and can be saved as a .nerulio file.
Does it need Aseprite or an engine plugin installed?
No. .aseprite files are read and written in the browser, and each engine bundle carries what that engine needs (for Godot, the import settings and scene; for Unity and the Godot TileSet, a small editor script).