Lithophane Maker

Common questions

How do I make a lithophane from a photo?

Press Choose image, or drop a picture on the dark stage: PNG, JPEG, WebP, GIF and BMP files open. Set the width and height of the picture area in millimetres (Keep aspect holds the picture's shape), the border, the thinnest and thickest points and the grid. The preview shows the plate lit from behind. Then press .stl: the page writes the binary STL, checks it and downloads it. The example harbor, a picture drawn by the page, shows the whole process.

How does brightness become thickness?

Each pixel's brightness L is (0.299 R + 0.587 G + 0.114 B) / 255, with any transparent part laid over white. Each grid cell takes the mean L of the pixels under it, and its thickness is thinnest + (1 - L) x (thickest - thinnest), so white is the thinnest point and black the thickest. At 0.8 and 3.0 mm, gray 128 comes out 1.90 mm. Invert swaps the ends. Each corner of the face takes the mean thickness of the cells that touch it, so where white meets black the corners on the seam sit halfway. Border cells are the thickest setting.

What sizes, thicknesses and grids can I set?

Width and height of the picture area run from 10 to 300 mm, the border from 0 to 20 mm, and the thinnest and thickest points from 0.2 to 20 mm, with the thickest at least the thinnest. The grid is 0.2, 0.25, 0.3, 0.4, 0.5 or 1 mm. The page starts at 100 x 75 mm, a 3 mm border, 0.8 to 3.0 mm and a 0.25 mm grid, and it remembers your settings on this device. It does not say which settings suit your printer or filament.

Is the STL watertight?

Yes. The back is flat, the face and the back each cover the full grid, and the four sides join them cell by cell. Before the download, the page reads the file back, joins corners whose coordinates match exactly, and checks that each edge is walked by exactly two triangles in opposite directions, that every stored normal follows its triangle's winding, and that the enclosed volume is positive, which means the normals point outward. A file that fails, or that the browser lacks the memory to check, is not downloaded. Two of the rows under the stage run the same check on small meshes at your current thickness, the plain-white slab also at your current size.

How big will the STL file be?

It is a binary STL: 84 bytes plus 50 per triangle. The face and the back have two triangles a cell and the sides two a cell along the edge, so a grid of X by Y cells makes 4 x X x Y + 4 x (X + Y) triangles. 100 x 75 mm with a 3 mm border at the 0.25 mm grid is 424 x 324 cells, 552,496 triangles and 27,624,884 bytes (27.6 MB). The page writes up to 2,000,000 triangles (100,000,084 bytes) and says so before building anything larger; a coarser grid or a smaller size brings it under.

Does the preview show how my print will look?

No. The backlit preview is a shading of thickness: brightness falls by a fixed factor of exp(-0.9) for each millimetre over 0.5 mm, so thin parts glow and thick parts stay dark. How a real print looks depends on your filament, printer settings and light, which the page cannot know. The Relief view shows the face lit from the upper left.

Is my picture uploaded, and how large a picture can it open?

Nothing is uploaded. The picture is decoded and sampled in this browser tab, and the page remembers only its settings, never the picture. Before decoding, it reads the picture's declared size from its header and refuses one over 16,384 pixels a side or 100 megapixels, with a message saying so. A picture over 8 megapixels is scaled down to about 8 megapixels before it is sampled.