Photo to Lithophane: choose the crop and tones
Prepare a photo for a flat lithophane: keep the subject, compare the tones under simulated light and save a closed STL without uploading the image.
Local browser processing · No upload · No account required
JPG, PNG, WebP, HEIC or AVIF. Flat rectangles only. The width includes the frame; frame height is its thickness.
Choose a photo to begin.
Mesh limit: at most 40,000 grid cells and 400 cells on either side. Photos are reduced to a preview up to 1,600 pixels on its longest side; the output uses that preview.
Size, triangles and file size appear here before saving.
How to turn a photo into a lithophane
- Open your photo and choose a crop shape. Look for a subject that stays clear without color and stands apart from its background.
- Move the rectangle over the subject. Resize it from an edge or corner to remove distractions, keeping enough space around hair, hands or other details near the edge.
- Enter the panel width and compare the backlit preview. Change brightness when the whole image feels dark, and contrast when neighboring tones need more separation.
- Check the calculated height and mesh size. Save the STL when the crop reads well, then inspect the model in your slicer before deciding on a printing orientation.
I start with the photograph
For this conversion I care first about the crop. A border through the middle of a hand is still distracting when the photograph becomes a thickness map. I use the ordinary image on the left to judge composition, then the simulated backlight to judge which parts remain readable.
The preview shows what happens to the photo in the browser. It cannot promise the same result under your light or with your filament, so keep the original file and treat the STL as one interpretation of it.
What changing the crop does to size
The maker calculates panel height from width and the crop ratio. These examples come from its size calculation with a width of 100 mm; the border is included inside those dimensions.
| Crop | Width | Calculated height |
|---|---|---|
| Square | 100 mm | 100 mm |
| Landscape 3:2 | 100 mm | 66.67 mm |
| Portrait 2:3 | 100 mm | 150 mm |
Choose a photo that survives grayscale
Color differences do not always become brightness differences. A red subject against a green background can lose separation when converted. I check the backlit view before spending time on fine settings. If the outline disappears there, cropping closer or choosing another photograph may help more than increasing resolution.
Dark tones print thick and bright tones print thin, so a large bright sky becomes a broad thin area and a dark coat a thick patch. The preview shows that relationship in a flat view, with no model to rotate.
Make tonal changes without losing the subject
Brightness shifts the input toward lighter or darker values. Contrast changes how far the tones sit from middle gray. Both controls stop at the darkest and brightest possible values, so a strong adjustment can erase texture. I compare the face, the background and the brightest area after each change, rather than judging only the overall brightness.
The default thickness range is 0.8 to 3.0 mm. It is a tool setting, not a guarantee for every printer. Invert is available for unusual source images, but leave it off for an ordinary positive photo. Otherwise the sky becomes thick and dark under backlight while the shadows become thin and bright.
Keep the crop and frame in agreement
The frame occupies space inside the panel size. A large frame can cover edge details, especially on a narrow portrait crop. I leave room around the subject and inspect the dark outline in the preview. Frame height is its thickness from the back, rather than the vertical size of the photograph.
The editor works from a reduced copy of the source, and the mesh has a fixed limit. The report tells you which resolution was used. Adding more source pixels cannot bypass the cap, and changing the width affects sampling density as well as physical size. When the composition is ready, inspect the downloaded file at its intended scale in a slicer.
Tips for better results
- Keep eyes and outlines away from the inner edge of the frame.
- Compare a subtle contrast change with the original setting before making it stronger.
- Treat smooth blank areas as part of the composition; they also become areas of similar thickness.
Privacy
Your photo is processed in your browser and never leaves your device. No upload or account is needed to create the STL.
Frequently asked questions
Which photos can I convert?
Choose a JPG, PNG or WebP that your browser can decode. Portraits and other clear subjects are useful starting points. A supported file still needs a suitable crop and enough tonal separation to read under simulated light.
Will the lithophane keep the colors?
The STL describes a shape, not colored ink or filament changes. This maker converts the photo to grayscale thickness. Its backlit preview is monochrome, so compare subjects by brightness rather than expecting their original colors to remain.
Can I change the height separately?
Height follows the crop ratio and the width you enter. To make the panel taller relative to its width, choose a portrait rectangle. To keep the existing composition, retain the original rectangle and change only its width.
Is the preview a picture of the final print?
It is a simulated view of light passing through the calculated thickness. It does not measure a filament or a lamp. Use it to compare crops and tonal changes, then assess the sliced file and physical material separately.
Related tools and guides
- Lithophane Maker: turn a photo into a light panel: Make a flat photo lithophane with a backlit preview and a solid STL.
- Image to Lithophane STL: size the download: Make a binary STL from an image with a flat back and closed sides. Check the dimensions, sampling grid, triangle count and download size before saving.
- Lithophane Generator: control the thickness map: Control how a photo becomes plastic thickness. Compare minimum, maximum and frame settings in a backlit preview, then generate the flat panel STL.
- Work out how large your photo can print: Convert pixels and print dimensions; change JPEG DPI tags.
- Make a contact sheet of your photos: Print a page of thumbnails with captions and EXIF lines as a PDF or page images.
- Make a passport photo at home: Passport and visa photos to official sizes, with a printable 10 x 15 cm sheet.
- How I use background blur: Separating a subject before converting a photo to thickness.