Specular Map Generator
Create a controlled specular-reflectance map with an explicit IOR/F0 target instead of confusing brightness, roughness, and metalness.
Upload and preview without signing in. Sign in to download 256px and 512px PNGs. Mapper+ unlocks 1K, 2K, original-resolution export, and all six non-albedo PBR maps in one workspace.
Variation source to Specular map preview
Upload and preview a dielectric specular/F0 map without signing in, choose linear F0, Unreal scalar, or legacy intensity output, then sign in to export a PNG.
Privacy: image decoding, pixel processing, preview, and PNG download run locally in the browser.
What should a specular map represent?
A specular map controls the strength or color of surface reflection at the viewing-normal angle; it does not control highlight width. For a dielectric, the baseline F0 follows ((IOR − 1) / (IOR + 1))², so IOR 1.5 is about 4% reflectance. Roughness controls reflection spread, while metalness selects the conductor workflow. This generator anchors output to an explicit target and uses source luminance only as optional variation around that baseline.
- IOR 1.5
- F0 ≈ 0.04
- Roughness
- Controls reflection spread
- Metallic surfaces
- Use conductor color/workflow
- Texture type
- Usually linear scalar data
How to use the Specular Map Generator
Choose the destination encoding
Use Linear F0 for a physical reflectance texture, Unreal scalar for the Unreal Specular input, or Legacy intensity only when an older shader expects it.
Set the dielectric baseline
Choose IOR for the material. Common nonmetals stay near 1.3–1.6; do not infer this value from photographed highlight brightness.
Add restrained variation
Use source luminance as a mask around the baseline only when the surface truly has spatially varying dielectric reflectance. Roughness variation belongs in a roughness map.
Export and verify in the shader
Download PNG, import it with the expected color-space setting, and compare against the renderer default before changing the whole material.
Specular, roughness, and metallic answer different material questions
Keeping these controls separate prevents dark plastics, over-bright stone, and highlights that never change width correctly.
| Signal | Controls | Common mistake |
|---|---|---|
| Specular / F0 | Reflection strength or color at normal incidence. | Using it to make highlights sharper. |
| Roughness | Reflection blur and highlight width. | Treating white as more reflective. |
| Metallic | Dielectric versus conductor response. | Using gray values for dirty metal boundaries. |
| Emission | Light added by the surface. | Using specular to fake self-illumination. |
Specular Map Generator FAQ
Is a specular map the inverse of roughness?
No. Specular controls reflection strength or F0; roughness controls how spread out that reflection is. A surface can be rough and still have the same dielectric F0.
What value represents 4% reflectance?
In a linear F0 map, 0.04 is about byte value 10. In Unreal’s Specular input, the documented default 0.5 represents roughly 4% for a dielectric.
Do metallic materials need this dielectric specular map?
Usually not in a metalness workflow. The conductor response is derived from base color and metallic. Use a dedicated specular-color workflow only when the destination shader calls for it.
Can image brightness measure specular reflectance?
Not reliably. A photo mixes lighting direction, exposure, roughness, Fresnel angle, color, and reflections; use source luminance only as a controlled variation mask.
Is the Specular Map Generator free?
Yes. As of August 26, 2026, the Specular Map Generator is free after sign-in. Free accounts can process images in the browser and export 256px or 512px PNG files.
Which Specular Map Generator export sizes require Mapper?
Exports above 512px require Mapper or a higher plan. Mapper+ unlocks 1K, 2K, and original-resolution export in the standalone tool, plus the full PBR Map Generator for creating normal, height, roughness, metallic, ambient occlusion, and emission maps together.