Convert a line drawing from raster to vector

Question

I have a raster image, basically a scanned drawing of the outlines (and some detail) of various objects, and I wish to convert these lines to vectors, using either Illustrator or Inkscape.

My present solution is to have the raster image as a background layer, and in a new layer above it I use the pen to follow the lines as close as possible. Later I tweak these lines to fit the raster image better. That has worked fine for simple drawings. However for some of my extremely complex drawings, this is very tedious to do.

Is there any tool or filter of some sort that is capable of recognizing the lines in line drawings and creating vector paths from them?

Answer 1

In inkscape, you count on sort of Potrace(an excelent tracer, free) embedded there. Just go to top Path menu, vectorize. I've played quite with its settings, and while you won't get total control you can reduce it to quite an accurate result and few nodes. But you need to play a lot with the settings till you find the right ones for you. It worked for me for producing game line-art from rasters (in a very similar style to comics drawings)

Other ways I used is forcing Illustrator to do a kind of averaging, in stroke settings. And lately, using the free MyPaint, because it has quite a lot of settings(more than in many commercial packages) to control your stroke and does a fix in real time of the trembling stroke (btw, the reason why it takes more time inking with pen tablets is as the electro magnetic system andmaybe the resolution is not as accurate as your hand, pen and paper.Often a low resolution table, like Intuos Small, is not enough, and you need a bigger format for better control. IMHO, is best the biggest formats. (a lot of people think other way, but imho, for inking is just like that.))

Answer 2

Illustrator has a feature called live trace. It sounds like it would be perfect for your case.

Place the source image. With the source image selected:

Object > Live Trace > Make.

OR

Object > Live Trace > Tracing Options. Set tracing options, and then click Trace.

You can then convert the tracing to paths.

Answer 3

For Illustrator CS6 or Illustrator CC.....

Open or Place the raster image into Illustrator.

Select the image and click the Image Trace button in the Control Bar across the top of the screen.

To refine the tracing, choose Window > Image Trace and you can adjust the trace options in the Panel which opens.

In previous Illustrator versions there was Live Trace. However, the feature was completely rewritten, from the ground up, for Illustrator CS6. Image Trace performs the same basic functions as Live Trace used to. Although being similar to Live Trace, Image Trace is entirely different, with different logic, features, and options.

Answer 4

I frequently have similar situations where I'm given some drawing -usually graphite pen drawings (sketchy, hairy lines sigh)- where drawing with the pen tool gets really tedious up to annoying.

I found my digital tablet to be very effective for tackling this situations. Even though I end up tracing the original image again, I do tend to have it done in less time than before. It took me usually up to 12-20 hours of work per sketch. Now I´m down to "just" 3-4hours.

I have done a few tries with livetrace in Illustrator but end up spending more time correcting or -in the best cases- using the results only partially.

For technical illustrations there seems to be no easy way around re-tracing the thing manually. At least I know of no automatic one.

Sometimes I'm able to take advantage of Rhinoceros which is a 3D software that allows you to export a view (perspective, parallel) of your model as vector lines (*.AI files). If you have some praxis in modeling you will be able to create the objects in 3D and take advantage of the possibility to export multiple views. Rhino-exported illustrator files still need some touching up. especially since lines tend to get very fragmented but at least you get a manageable amount of nodes (still more messy than tracing manually).

Hope this helps

Answer 5

First, prime your image to make the job of the raster-to-vector conversion utilities/ algorithms easier

1. Scan your image as Black and White, and then as Grey Scale (sometimes one works better than the other). Scan at the highest resolution you can manage 600dpi or 1200dpi, if your computer can handle it.
2. Use Image > Adjustments > Levels to correct for paper that is not completely white
   1. Optionally, adjust brightness/ contrast levels as well at this stage. You are trying to maximise the perceivable difference between the lines and the blank parts of your drwaing.
3. Apply Posterize to accentuate the lines

Now apply the vectorize techniques as mentioned in previous answers. For Illustrator, Live Trace, followed by manual touch-ups works quite well.