Tracing images that aren’t black and white using Inkscape

Sometimes you want to trace images that aren’t a nicely contrasted black and white.  They might be line art with faint lines, colored clip art, or have several shades of gray.  You can always use your favorite photo editing software to manipulate the image, but many times you can get a good trace in Inkscape by changing the “Brightness cutoff” threshold.  Here is how you do that.

Images with empty or incomplete traces

Here I have a line art image with pale lines.

Halloween_ghost_2

If I tried to trace it with the default threshold of 0.45 the preview and the trace would be empty.  The Brightness cutoff threshold needs to be increased to trace the pale lines.  In the image below I have increased the threshold to 0.90 since the lines are so faint.  With the image selected, I have clicked on “Update” to get an idea of how the image will trace.

Trace non ideal1

Since I know that traces are almost always darker than the preview, I will click “OK” to trace the image.  The image below shows what the trace looked like.  All of the lines are traced with no breaks or holes in them.  If you had an image that traced but left gaps or small holes inside the lines, you would need to increase the threshold until the lines trace as solid lines.

Trace non ideal2

Colored images, or images with dark traces

Sometimes you want to trace an image with shades of gray or with colors, such as a colored clip art, but the trace using the default settings gives a blotchy trace, or areas that are solid that shouldn’t be.  Below is a colored clip art that has black sections when traced with the default settings.

Trace non ideal3

The Brightness cutoff threshold needs to be decreased to remove the darker colors from the trace.  In the image below I have decreased the threshold to 0.20.  With the image selected, I have clicked on “Update” to get an idea of how the image will trace.

Trace non ideal4Since the preview looks good, I will click “OK” to trace the image.  The image below shows what the trace looked like.  If more of the image traces than was wanted, simply keep reducing the threshold and click “update” until just the black lines are traced.

Trace non ideal5If a trace is not tracing enough of the image, try increasing the Brightness cutoff threshold.

If a trace is tracing too much, try decreasing the Brightness cutoff threshold.

Some images just won’t trace well and will need to be cleaned up after tracing, or a different method should be used, such as manually outlining using the Bezier tool.

Advertisements

7 Responses to Tracing images that aren’t black and white using Inkscape

  1. Dyan says:

    This program is amazing

  2. Mazaheri Law says:

    First-time visitor here. Love your site and only had a chance to glance at what else you have posted here but I’m subscribed and look forward to more quality content!

  3. broomhilde says:

    Heather you are a dream-come-true! In plain language you’ve taught me a lot. Since I am a week-new into SCAL & Inkscape, I have much and more to learn. I run a windows XP. My problem I have now is step for step to find an imge I want,GET it into Inkscape, (I assume then I goto file-save as a named, desktop.
    Ha! Now when I go into SCAL and file-import-named pic on desktop-HELP! I can’t find the pic!!! What am I doing wrong!

    I would appreciate any and all advice you or others can give me. I do have many software programs with image libraries, etc (at my disposal) Some pics there are vector already. But I want to use whatever.

    So many thanks in advance for even hearing me out.

    • imagesbyheatherm says:

      Hi Broomhilde, you can open, import, or paste images into Inkscape files. Once you do that, you need to convert them to vector form by either tracing them or using the paint bucket tool (I prefer tracing). All text, shapes, and images must be converted to Path (vector) before they can be cut in SCAL, and just saving as “svg” does Not convert them to vector. After making a vector image, be sure to save the file as an “svg”.

      I would recommend creating some kind of file system rather than saving things to the desktop. Most people use a main folder with sub-folders by category.

  4. Thanks for the tutorial.

  5. TeresaW says:

    This tutorial is just brilliant, and just what I need. I have linked it to my Tutorial Blog (http://treesawardintutorials.blogspot.com/2009/10/tracing-images-that-arent-black-and.html) as a reminder for me, I do hope you don’t mind, but there is no point in reinventing the wheel when you did such a nice job of it.

  6. Toni says:

    Thank you so much for the excellent tutorial.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: