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3DToolBench

Turn an STL into a JPG

This is not a conversion and it is worth being clear about that. A picture of a model is a render: it is flat, and there is no way back from it to the shape. What this page gives you is a clean image of your model from the angle you choose, for a listing, a document or a message.

Drag a 3D file here, or.

This page is set up for STL files. Other formats we can read work here too.

The file is read on your own computer. It is never uploaded.

Add a file to switch this on.

Your file is read by your own browser and never sent to a server. There is no upload, no account and no copy of your model anywhere but on your computer.

You are framing the picture, not converting a file

Every other page on this site turns one file into another and the result does not depend on what you were looking at. This one does. The picture is exactly what is in the 3D view — same angle, same zoom, same size on screen — so the way you leave the model is the way the picture comes out.

Drag to rotate, scroll to zoom, and use the grid and wireframe buttons if you want them in or out of the shot. When it looks right, press the button.

That also means the picture is as large as the viewport is on your screen. On a desktop monitor that is a comfortable size for a listing or a document. On a phone it is small, and a wider browser window is the way to get a larger picture.

Why the background is white, and when you want PNG instead

JPEG has no transparency. None at all — it is not a setting, the format has nowhere to record it. So the render is taken on a white background, which is what a product listing, a printed document and a spreadsheet all expect.

If you want the model cut out, with nothing behind it, choose PNG instead in the format box. A PNG of the same model comes out with a transparent background and drops onto a coloured slide or a dark page without a white rectangle around it.

The short rule: JPEG for a photograph-like picture going somewhere white, PNG for anything you are going to place on top of something else.

What a picture is good for, and what it is not

Good for: showing somebody what a part looks like, a listing on a marketplace, an illustration in a document or a manual, a thumbnail, a message to a client who does not have CAD software.

Not good for: anything anybody needs to measure, print or edit. The picture holds no dimensions, no geometry and no scale. If somebody needs the part, send the STL — it is usually smaller than the picture anyway.

And there is no way back. No tool can turn a photograph or a render into a 3D model, because the shape was never recorded. A picture stores how bright each point was, not how far away it was.

What survives, and what does not

Kept in the JPEG file

  • Exactly the view you framed, at the size of the 3D viewport
  • The shading, so the shape reads clearly in the picture

Lost on the way

  • All three dimensions — a picture is flat, and there is no way back
  • Any scale or measurement; the picture records no sizes
  • Transparency, which JPEG cannot store — choose PNG if you need it

How to convert STL to JPEG

  1. Drop the .stl file in

    The model appears in the 3D view, framed to fit.

  2. Turn the model to the angle you want

    Drag to rotate, scroll to zoom. A three-quarter view usually reads better than a straight-on one, because it shows depth.

  3. Decide about the grid and the wireframe

    The buttons in the corner of the viewport switch them off. For a clean picture, off is usually right.

  4. Make the browser window as large as you want the picture

    The image is taken at the size of the 3D view on screen, so a wider window gives a larger picture.

  5. Press the button and save the JPG

    Choose PNG in the format box instead if you need the background cut out rather than white.

STL and JPEG compared

STL and JPEG compared, row by row
PropertySTL.stlJPEG.jpg .jpeg
File contentsBinary or plain text. Binary is an 80-byte header, a triangle count, then 50 bytes per triangle.Binary, compressed by throwing away detail the eye does not notice. Saving again loses a little more each time.
GeometryTriangles only. Curves are approximated when the file is made, and cannot be recovered.None. It is a grid of pixels.
UnitsNone. The file stores bare numbers, and every reader has to guess what they mean.An optional density in the JFIF or Exif header, meant for printing on paper.
Colour and textureNone. There is no place in the format for a colour, a material or a texture.8 bits per channel, and no transparency at all.
Separate objectsOne body. Several parts written into one STL become one undivided lump of triangles.One image, usually with camera settings recorded beside it.
Published by3D Systems, 1987, for the first stereolithography machines.The Joint Photographic Experts Group, 1992. Now ISO 10918.
Written byEvery CAD program and every slicer, as the common denominator.Every camera, every phone and every image editor.

Questions

How large is the picture?
The same size the 3D view is on your screen, in pixels. Widen the browser window before taking it if you want more. There is no fixed resolution to choose because the render is the viewport itself.
Can I get a transparent background?
Not in a JPEG — the format cannot store transparency. Choose PNG in the format box and the background comes out transparent.
Can I turn a JPG back into an STL?
Not into a model of the object, no. A picture records brightness, not distance, so the shape is simply not in the file. What can be done is treating brightness as height, which makes a relief — that is what the image to STL tool does, and it is the right answer for a plaque or a lithophane rather than for recovering a part.
Why is the picture empty?
The 3D view has to be on screen when the picture is taken, because the renderer stops drawing while it is scrolled out of sight. Scroll up so the model is visible and press the button again.
Is my model uploaded?
No. The render happens in your browser using your own graphics hardware. Nothing is sent anywhere.

Where to go next