Today I started to vectorize some old black and white handdrawn designs I created a long time ago. And I ended up with the problem, that some of the scans had a lot of speckles. One of this drawings was the following “skeleton sperm” or whatever you wanna call it:
Doesn’t look that bad, but when you some in you can see a lot of annoying pixels around the lines:
When using Inkscapes “Path >> Trace Bitmap …” feature to vectorize the above image, I ended up with yome really ugly paths:
Years ago I used to remove this either in the bitmap or the path with a lot of effort by hand. Today I found a really nice technique to avoid all that tiresome work.
Step 1: Add Mask to Image
- Open your scanned drawing in Photoshop.
- Use “Image >> Adjustment >> Brightness / Contrast…” and increase the Brightness and contrast a bit to remove all the potential noise you have in the white part of the image.
- Open “Window >> Channels” and Ctrl-Click the RGB Layer to make a selection of the image.
- Add a mask to you drawing using “Layer >> Layer Mask >> Hide Selection”
Step 2: Refine Mask
Now you can use the “Select >> Refine Mask Feature to refine the Selction and get a smoother look. For me the following settings have worked well. This depends on the size of your image and other factor, have fun playing around with these sliders.
Step 3: Create a Solid Color Layer
- Use Ctrl+Click on the refined layer mask to create a selection from the layer mask.
- Use “Layer >> New Fill Layer >> Solid Color” and choose black as the color.
Step 4: Vectorization
Save the image and open it in Inkscape. When you now trace the bitmap image using “Path >> Trace Bitmap …” the result will get much smoother without all the speckles.