PNG to STL Converter
Turn a PNG into a printable lithophane: a thin panel whose thickness follows the brightness of the picture, so the image appears when a light shines through it.
3D Model Converter
or drop STL, OBJ, MTL … files here ·
Max 95 MB per file· Up to 20 files· Deleted after 30 minutes
Files are processed on our servers and deleted after 30 minutes.
STL and OBJ store no units. If a part shows up 10× or 25.4× too small or too big in the slicer, the units were read wrong — set them here.
Blender, CAD programs and slicers use Z-up; glTF, Unity and most game engines use Y-up. Switch it if the model lies on its side after import.
Used when converting STEP or IGES solids to a mesh. Fine gives smooth curves but larger files; coarse is enough for quick previews.
Only used for PNG, JPG or SVG input. Relief raises dark areas; a lithophane is a thin panel that shows the photo when lit from behind; extrude turns a logo or SVG outline into a flat solid shape.
Width of the printed model; the height follows the image's aspect ratio.
Maximum raised height for a relief or lithophane, or the thickness of an extruded shape. Lithophanes usually use 2–3 mm.
Solid plate under the relief so the print holds together. 0 means no base.
How to use this tool
- 1
Upload the PNG
Add one PNG or up to 20 at once. JPG, BMP and WebP also work, but a PNG keeps the smooth tones a lithophane needs.
- 2
Check the panel size
Image becomes is set to Lithophane, 100 mm wide, with Height / depth 2.4 mm on top of a 0.8 mm Base thickness. The height follows the picture's proportions.
- 3
Convert to STL
Press Convert to STL. The binary STL opens in Cura, PrusaSlicer, Bambu Studio or any other slicer.
PNG to STL conversion maps every pixel's brightness to a thickness: a white pixel becomes 0.8 mm of plastic, a black one 3.2 mm, and the grays fall in between.
How a PNG becomes a lithophane STL
Lithophanes are nearly two centuries old: porcelain plaques with the picture carved as varying thickness were patented in France in 1827. A 3D printer does the same thing in plastic. The converter reads your PNG as a grid of gray values, raises a surface over that grid, and closes it with a flat back and sides so the slicer receives a solid, watertight panel.
PNG suits this job better than the photo formats around it. It is lossless, so the gradients on a face or sky carry no compression blocks that would print as ridges. The original 1996 specification also allows 16-bit grayscale, which is why terrain tools export height maps as PNG; for a lithophane, the familiar 8-bit gray already gives steps far finer than any printer layer.
STL, defined by 3D Systems in 1987, stores nothing but triangles. No pixels, colors or units travel with it, so the size you set here in millimeters is the size your slicer will show, because slicers read STL numbers as millimeters.
PNG to STL lithophane settings in numbers
- thinnest plastic, where the PNG is white
- 0.8 mm
- thickest plastic, where it is black
- 3.2 mm
- gray levels in an 8-bit PNG
- 256
- thickness per gray level over 2.4 mm
- 0.0094 mm
Prepare the PNG
Crop to the subject, raise contrast slightly and keep faces large. Small details below about 0.4 mm, a typical nozzle width, will not resolve.
Pick the panel width
100 mm suits a desk frame. For larger panels raise Model width; the thickness range stays the same, so the image does not get darker.
Light it from behind
A daylight LED panel or a phone flashlight behind the print shows the image; in normal room light it looks like a plain white tile.
PNG
Portable Network Graphics
PNG is a lossless raster format published in 1996 by the PNG Development Group and later standardised by the W3C and ISO. It keeps every pixel exactly, supports full alpha transparency and handles text, sharp edges and flat colours without artefacts. That precision makes it ideal for screenshots, logos, icons and interface graphics. The trade-off is size: photographs saved as PNG are often several times larger than the same photo as JPEG or WebP. All browsers, operating systems and editors open PNG files.
- Compression
- Lossless
- Transparency
- Yes
- Animation
- No
- Introduced
- 1996 · PNG Development Group
STL
STL mesh
STL (stereolithography) is a 3D mesh format created by 3D Systems in 1987. It describes only the surface geometry of an object as a list of triangles, without colour, materials, units or scene information. Its simplicity makes it the default input for 3D printing slicers such as Cura and PrusaSlicer. Curved surfaces are approximated by many flat triangles, so smooth models can produce very large files.
- Compression
- –
- Transparency
- –
- Animation
- No
- Introduced
- 1987 · 3D Systems
People convert PNG to STL to print a picture as a physical object, most often a backlit lithophane, because a slicer needs triangle geometry and a PNG only holds pixels.
Relief and logo shapes from a PNG
Lithophane is one of three modes under Image becomes. Relief raises the dark parts of the picture on a solid base, like a coin or embossed plaque, and is meant to be seen in reflected light. Extruded shape traces the outline of a logo or icon and turns it into a flat solid, the way keychains, door signs and cookie stamps are made. The general image to STL converter starts in relief mode and explains how many pixels each print size needs.
Pixel count matters most in extruded mode, because a raster outline is a staircase. A 200 px wide icon stretched to 100 mm has steps of half a millimeter along every curve, which a printer reproduces faithfully. Upscale the PNG or trace it to vector first; how to convert PNG to SVG covers the tracing route.
PNG to STL questions
Why does a lithophane from a JPG look blotchy while a PNG looks smooth?
JPEG compression works in 8 × 8 pixel blocks and leaves faint steps between them. On screen they are invisible, but in a lithophane every brightness step becomes a thickness step, so the blocks print as a grid of tiny ridges. A PNG has no such artifacts.
What should I do with the transparent background of my PNG?
Fill it with a solid color before converting, white if the area should glow brightly and black if it should stay dark. Transparent pixels have no brightness of their own, so a flat fill makes the result predictable.
Does a color PNG work, or must it be black and white?
Color works. Only brightness is used to build the panel, so the colors are reduced to gray tones first. If two colors of similar brightness sit side by side, such as red and green, they look almost the same in the print; raising contrast in a photo editor helps.
Can I make a curved lithophane for a lamp?
This converter makes a flat panel. Flat lithophanes sit in a picture frame, a window or on an LED light box; a curved shade needs a lithophane generator or CAD software that bends the panel.
How do I turn a PNG logo into a solid STL instead?
Set Image becomes to Extruded shape. The logo's outline becomes a flat solid of the thickness in Height / depth, good for keychains and signs. If the logo also exists as a vector file, SVG to STL gives cleaner edges.
Why are the bright parts of my lithophane thin?
That is how lithophanes work: thin plastic lets more light through, so bright areas must be thin and dark areas thick. The converter inverts the image for you in this mode, so leave Invert heights off.
