# Image to STL Converter

> An image to STL converter is a tool that turns a flat picture into a 3D-printable mesh. Kenerate's free converter works in your browser three ways: a relief (brightness becomes height), a lithophane (the picture shows when backlit) or an extruded shape from a logo. Set the size in millimetres and download a watertight STL or 3MF.

URL: https://kenerateai.com/image-to-stl
Publisher: Kenerate AI (https://kenerateai.com)
Last updated: 2026-10-01

## Key facts
- Price: Free, no account
- Input: JPG, PNG (transparency supported), WebP, GIF, BMP — up to 40 MB
- Modes: Relief · Lithophane · Extrude shape
- Output: STL, 3MF, OBJ, GLB — watertight, in millimetres
- Detail: 0.1–1 mm grid, up to 640 samples per side · relief default 100 mm wide, 2 mm base, 3 mm relief
- Privacy: Processed in your browser — no upload
- Relief — brightness becomes height: Light areas rise, dark areas stay low (or the reverse with Invert). Great for depth maps, coins, embossed tiles and textured signs.
- Lithophane — a photo made of light: Dark areas are printed thick and bright areas thin, so the photo only appears when light shines through. Frame and curve options included.
- Extrude — logos and silhouettes: Pixels darker than a threshold (or the opaque part of a transparent PNG) become a solid shape — signs, badges, cookie-cutter outlines.
- Watertight by construction: Every mesh is a closed solid — top surface, flat bottom and side walls — so slicers don't need to repair it.
- Real millimetres: Set the width; height follows the picture's aspect ratio. Base and relief heights are in mm too, so the file prints at the size you see.
- Private: The picture is read on your device. Nothing is uploaded or kept.
- Resample: The image is redrawn onto a grid at your chosen detail — one sample every 0.1–1 mm across the width.
- Measure brightness: Each sample's luminance (Rec. 709 weights) is read; transparent pixels count as background.
- Map to height: Relief: bright = high. Lithophane: dark = thick. Extrude: dark or opaque = solid.
- Close the solid: A flat bottom and side walls are added so the mesh is watertight, then it's written as STL, 3MF, OBJ or GLB.
- STL (Stereolithography): Triangle mesh (binary or ASCII); by 3D Systems, 1987. Holds: Triangle surfaces, Facet normals. Lacks: Colour and textures, Units, Materials. Best for: 3D printing — every slicer opens it. Opens in: Cura, PrusaSlicer, Bambu Studio, OrcaSlicer, Blender.
- 3MF (3D Manufacturing Format): ZIP package with XML; by 3MF Consortium, 2015. Holds: Meshes with units (millimetres), Colours and materials, Several objects and build plates. Lacks: Animation. Best for: Modern 3D printing and multi-colour prints. Opens in: Bambu Studio, PrusaSlicer, OrcaSlicer, Cura, Windows 3D Builder.
- Relief: What it does: Brightness → height on a solid base | Best for: Depth maps, textures, embossed tiles
- Lithophane: What it does: Darkness → thickness, viewed against light | Best for: Photos of people, pets and places
- Extrude shape: What it does: Dark or opaque pixels → one solid height | Best for: Logos, icons, silhouettes, text images
- AI image to 3D: What it does: A full 3D object reconstructed from the photo | Best for: Figures, products and characters — in the 3D Studio

## Steps
1. Add your picture — Drop a JPG, PNG or WebP onto the box above — or try a sample.
2. Choose the type — Relief for raised pictures, Lithophane for backlit photos, Extrude for logos and silhouettes.
3. Set the size — Choose the width in mm, then the base and height (or min/max thickness for lithophanes).
4. Download — Pick STL or 3MF and download. Open it in your slicer and print.

## In depth

### Why there isn't one 'image to STL'
A picture is flat; an STL needs depth. Every converter has to invent that depth from something. Heightmap tools take it from brightness, lithophanes from darkness (to block light), extrusion from a mask, and AI image-to-3D from a learned guess of the hidden shape. Picking the method is the most important decision — the sliders come second.

### Brightness, polarity and contrast
Tools disagree on direction: some raise white, some sink it. Here Relief raises bright pixels by default, so a depth map (white = near) comes out right, and Invert flips it. The full brightness range maps onto your chosen relief height, so a low-contrast photo gives a shallow result — raise contrast before converting for a stronger relief.

### Detail, triangles and file size
STL stores every triangle at 50 bytes in binary form [1]. A heightmap makes about two triangles per sample, so doubling the detail in both directions quadruples the file. That's why this tool caps the grid at 640 samples per side — beyond that, files get too big for slicers and phones without visible gain at typical print sizes.

### Make it printable
Walls thinner than one perimeter (about 0.45 mm with a 0.4 mm nozzle) can't print; two perimeters, about 0.9 mm, is a safer minimum [11]. Keep a base of at least 1.5–2 mm under a relief so it doesn't warp, and print reliefs flat on the bed.

References:
[1] Wikipedia — STL (file format): https://en.wikipedia.org/wiki/STL_(file_format)
[2] Wikipedia — Wavefront .obj file: https://en.wikipedia.org/wiki/Wavefront_.obj_file
[3] Wikipedia — FBX: https://en.wikipedia.org/wiki/FBX
[4] Khronos Group — glTF: https://www.khronos.org/gltf/
[5] 3MF Consortium — 3MF specification: https://3mf.io/specification/
[6] Wikipedia — Universal Scene Description (USD / USDZ): https://en.wikipedia.org/wiki/Universal_Scene_Description
[7] Wikipedia — PLY (file format): https://en.wikipedia.org/wiki/PLY_(file_format)
[8] Khronos Group — glTF 2.0 specification: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html
[9] Apple — AR Quick Look: https://developer.apple.com/augmented-reality/quick-look/
[10] three.js — documentation: https://threejs.org/docs/
[11] Prusa Knowledge Base — Modeling with 3D printing in mind: https://help.prusa3d.com/article/modeling-with-3d-printing-in-mind_164135
[12] Prusa Blog — lithophanes and filament transparency: https://blog.prusa3d.com/lets-play-with-filament-transparency-how-to-make-amazing-lifelike-color-photos-with-just-a-simple-color-change_104338/
[13] Polymers (2024) 16(20):2862 — FFF parameters and translucency of PLA: https://doi.org/10.3390/polym16202862
[14] Wikipedia — Lithophane: https://en.wikipedia.org/wiki/Lithophane
[15] W3C — CSS Values and Units Level 3 (absolute lengths): https://www.w3.org/TR/css-values-3/
[16] Adobe Substance 3D — OpenGL vs DirectX normal maps: https://experienceleague.adobe.com/en/docs/substance-3d/bakers/common-questions/what-is-the-difference-between-the-opengl-and-directx-normal-format
[17] Blender Manual — Normal Map node: https://docs.blender.org/manual/en/latest/render/shader_nodes/displacement/normal_map.html
[18] Wikipedia — Normal mapping: https://en.wikipedia.org/wiki/Normal_mapping
[19] SIL Open Font License: https://openfontlicense.org/

## FAQ
Q: Can you convert an image to STL for free?
A: Yes. This converter is free, needs no account and runs in your browser, so there's no upload or watermark.

Q: Which mode should I use for a photo?
A: For a photo of a person, pet or landscape, a lithophane gives the most recognisable result. A relief works best when the image is already a depth map or has simple, strong shapes.

Q: Is it white = high or black = high?
A: In Relief mode, white is high and black is low; tick Invert to swap. In a lithophane, dark areas are thick (so they block light). In Extrude mode, dark pixels become the solid — or, for a PNG with transparency, the opaque pixels do.

Q: Will my STL be in colour?
A: No. STL has no colour. The shape carries the picture: as height in a relief, or as light and shadow in a lithophane.

Q: How big will the file be?
A: Each sample becomes two triangles on top (plus the base and walls), and binary STL uses 50 bytes per triangle. A 100 mm relief at 0.3 mm detail is about 110,000 samples — roughly 22 MB. Increase the grid step for smaller files.

Q: How thin can details be?
A: A 0.4 mm nozzle prints walls down to about 0.45 mm (one perimeter); 0.9 mm (two perimeters) is safer. Very fine lines in a picture won't survive at small sizes.

Q: Is there an image to STL AI?
A: Yes — that's AI image-to-3D, which builds a full object rather than a flat relief. The Kenerate 3D Studio rebuilds a full object from one photo with engines like Tripo, Meshy and Rodin; 3D generation needs a one-time credit pack.

Q: Is my image uploaded?
A: No. It's processed on your device and never sent to a server.

Q: Is this image to STL converter safe?
A: Yes. The picture is read and turned into a mesh by code running in your own browser tab — it isn't uploaded, stored or shared, and there's nothing to install. The STL you download is a plain triangle mesh that any slicer opens.

## Related pages
- AI 3D Model Generator: https://kenerateai.com/ai-3d-model-generator
- Image to 3D: https://kenerateai.com/image-to-3d-converter
- AI STL Generator: https://kenerateai.com/ai-3d-printing-model-generator
- Text to 3D: https://kenerateai.com/text-to-3d-generator

## Sources
- Wikipedia — STL (file format): https://en.wikipedia.org/wiki/STL_(file_format)
- Wikipedia — Wavefront .obj file: https://en.wikipedia.org/wiki/Wavefront_.obj_file
- Wikipedia — FBX: https://en.wikipedia.org/wiki/FBX
- Khronos Group — glTF: https://www.khronos.org/gltf/
- 3MF Consortium — 3MF specification: https://3mf.io/specification/
- Wikipedia — Universal Scene Description (USD / USDZ): https://en.wikipedia.org/wiki/Universal_Scene_Description
- Wikipedia — PLY (file format): https://en.wikipedia.org/wiki/PLY_(file_format)
- Khronos Group — glTF 2.0 specification: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html
- Apple — AR Quick Look: https://developer.apple.com/augmented-reality/quick-look/
- three.js — documentation: https://threejs.org/docs/
- Prusa Knowledge Base — Modeling with 3D printing in mind: https://help.prusa3d.com/article/modeling-with-3d-printing-in-mind_164135
- Prusa Blog — lithophanes and filament transparency: https://blog.prusa3d.com/lets-play-with-filament-transparency-how-to-make-amazing-lifelike-color-photos-with-just-a-simple-color-change_104338/
- Polymers (2024) 16(20):2862 — FFF parameters and translucency of PLA: https://doi.org/10.3390/polym16202862
- Wikipedia — Lithophane: https://en.wikipedia.org/wiki/Lithophane
- W3C — CSS Values and Units Level 3 (absolute lengths): https://www.w3.org/TR/css-values-3/
- Adobe Substance 3D — OpenGL vs DirectX normal maps: https://experienceleague.adobe.com/en/docs/substance-3d/bakers/common-questions/what-is-the-difference-between-the-opengl-and-directx-normal-format
- Blender Manual — Normal Map node: https://docs.blender.org/manual/en/latest/render/shader_nodes/displacement/normal_map.html
- Wikipedia — Normal mapping: https://en.wikipedia.org/wiki/Normal_mapping
- SIL Open Font License: https://openfontlicense.org/