What process can I use to print my picture so edges are embossed and can be felt?

Question

I often like to work on low-resolution pictures, adding some data moshing or compression artifacts. Some of them look ok when printed on paper (but I had to make sure the hard edges are preserved, so no interpolation was done when resizing, or I asked for no resizing at all).

But I would like to push the pixels / low-res effect one step further and have the file printed or engraved or embossed, so that the hard egdes in the file can be felt by the finger. The result would be a normal frame that can be hung in the living room, but with a slight relief corresponding to, for exemple, each pixel's luminance level (or maybe I would need to compute and provide another special layer).

From some googling I think embossing produces soft edges, and it not used for big frames printed only a few times. I did not see any "engraving" printers, but I do not even know the name of what I am looking at.

If it do not exists or is too expensive, I wonder if a simple two-levels only solution could be achieved by printing twice the picture, and then laser cutting one, and sticking it on the top of the other.

Anyone with experience in this?

Answer 1

As I work regularly with CNC machines (these are milling machines that can be controlled by a computer), I want to show you two methods that are being used to engrave images in a pixelated style which you can feel with your fingers.

The first method is used to make half tone images, which is very similar to low resolution images in newspapers. The difference is that the dots are milled using a V-bit, so you can feel every dot. An example is the following image (made by metalfusion):

Another method is used to make lithophanes. These are images made of a thin material that is translucent (Corian is often used), engraved with an image. Dark parts of the image are made by keeping the material thicker, as light parts are cut away to make the material more translucent.
Using this method you get the high-contrast lines as extra difference in height of the material, while low contrast parts are only a small difference in height. An example of a lithopane milled in corian is this one (found on the website of Vectric: software that can make lithophanes)

In the first image you can clearly see the high contrast lines being a good height difference in the material.

---

To answer the questions in the comment:

Lithophanes are made with a ball-nose. You could use a ballnose of say 1mm. That would technically give you a pixel (dot) size of 1mm. However, the CNC machine has a resolution of say 0.01mm (at least) and can change it height every resolution step. So in practice you get high resolution but your contrast is limited to the size of your tool.
In the iamges below you'll see the effect of the large toolsize compared to the resolution.

About the colors, I've never seen a multi colored lithopane. However you can use colored material as in the images above. It is probably possible to print over a lithophane, however the backlighting will not work so you can just as easy make a relief (such as the maps with terrain height relief).

Answer 2

What you are talking about is a sort of exaggerated Woodburytype or photorelief print. In the original process, a master print was created using a light-hardening process (an emulsion material was selectively hardened by exposure, and the unhardened material washed away). The master print was then pressed into a soft metal sheet, making a mold into which pigmented gelatin was poured, then transferred to paper, giving a relatively high-volume continuous-tone print suitable for binding into books. That process was, for better or worse, completely displaced by halftone printing. (The "better" part being that books and magazines with photos in them became an awful lot cheaper; the "worse" being that Woodburytypes are freakin' gorgeous and halftones... not so much.)

There is a modern method of creating Woodburytypes using a CNC mill (or a sign-carving machine, if you prefer) to carve the mold. You can make the print a dual-purpose print (looking and feeling) by simply adapting the process to make a deeper relief cut (scaling the z-axis of the milling operation) and using a less strongly pigmented printing material so that you get both an appreciable tactile experience and a beautiful monochrome print. And for reasons of practicality, it really does need to be monochromatic; you could conceivably create colour prints, but it would take a lot of trial and error and multiple plates which will get more and more difficult to align and lay down as the 3-D image is built.

There is a general article describing the CNC-adapted process here. I know that links are frowned upon as answers; the main part of the process is actually a native feature of sign-carving set-ups that have a raster processing facility. Since there will be a lot of experimentation involved in creating a successful print (particularly in selecting a printing medium to replace the traditional gelatin, pigmenting it to the right degree for the print thickness, and coming to a thickness that will have adequate relief for the tactile experience while maintaining the visual experience), the fact that in-depth instructions may go away some day is not much of a worry, and the process is too large and too fraught with uncertainties to include here in any detail.

It will be a Project with a capital P (and some capital investment), but you will probably find that the results, once you get what you want, will probably be spectacular.

Answer 3

You could certainly do this with a 3D printer; you'd have to convert the photograph to an actual 3D model, but it'd be straightforward from there.

3D printing is an emerging technology and outside of a few examples the consumer versions aren't really used for much more than trinkets, but it seems ideal for your application.