Turn an image into a printable lithophane STL: dark areas print thick, bright areas thin, so the picture appears when light shines through.
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A lithophane is a thin relief panel whose image is formed by thickness rather than colour. Held up to a light, the thin areas pass more light and look bright, while thick areas look dark. This generator samples the image to a grid, maps each pixel brightness to a thickness between the minimum and maximum settings (bright pixels become thin, dark pixels become thick), and builds a closed solid with that relief on the front, a flat back at zero, and walls around the edges, exported as a binary STL. The on-screen preview is a shaded 2D canvas where brightness stands in for height, which is enough to judge contrast before printing. Higher resolution gives smoother detail but larger files and longer slice times, so the grid is capped at 300 columns. Simple, high-contrast images work best; print with a light-coloured filament at 100 percent infill and a small layer height.
How does a lithophane work? Light passes through thin plastic more easily than thick plastic. By varying thickness with image brightness, the panel shows a picture when backlit even though it looks plain from the front.
What settings should I start with? The defaults, 100 mm wide, 3 mm maximum and 0.6 mm minimum thickness, 200 columns, are a good starting point for most photos. Increase columns for larger prints.
Why does my preview look washed out? Low-contrast images produce shallow relief. Choose a photo with clear light and dark areas, or accept a subtler result; the preview brightness mirrors the thickness map.