How to isolate components of traced bitmap

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bachrock
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How to isolate components of traced bitmap

Postby bachrock » Thu Jan 03, 2013 2:24 pm

So I just used the "Trace Bitmap" command on a silhouette I pulled from the internet. The silhouette has multiple distinct regions. When I click one such region, I'd like to only have that selected. How can I do this?

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brynn
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Re: How to isolate components of traced bitmap

Postby brynn » Thu Jan 03, 2013 2:47 pm

Image
Welcome to InkscapeForum!

When you traced it, did you do a single scan, or multiple scan? If it was a multiple scan, you can ungroup to get the individual colors. That may or may not make the subjects individual. If it doesn't, or if you used a single scan, you could try selecting, then Path menu > Break Apart. Chances are, this will make everything solid black. So try adding a stroke and removing the fill. That will make it easier to see what you have. If that doesn't do the trick, then the only way to make them separate objects will be with node editing.

If you have further questions, it might help us to see the traced image (before you do anything to it).

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Xav
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Re: How to isolate components of traced bitmap

Postby Xav » Thu Jan 03, 2013 9:52 pm

I have to do this a lot with parts of my 'Monsters, Inked' comics, and I've found only two practical ways to do it ("Break Apart" doesn't count as practical for a comic strip outline, as you end up with too many parts - it might work for you if your silhouette is simple).

1) Node editing. Literally making copies of the path, then selectively deleting nodes from each of them to leave you with several paths each containing part of the original. The "!" key can be very useful when it's easier to select the nodes you want to keep than those you want to remove. This approach, however, can be very slow.

2) Much faster, and the approach I usually use, is to make multiple copies of the path then use boolean operations to selectively remove parts from each of them. For example, draw a rough path over the bit you want to keep then select both paths and use Path > Intersection to chop out the rest. Or draw over the bit you want to remove and use Path > Difference.
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bachrock
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Re: How to isolate components of traced bitmap

Postby bachrock » Sun Jan 06, 2013 8:45 am

Great! It turns out I simply needed "Break Apart". Your other comments are helpful with what I want to do next. Thanks guys!

Jopublick
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Re: How to isolate components of traced bitmap

Postby Jopublick » Sat Aug 02, 2014 8:11 pm

Hello, I used break apart on a greyscale bitmap that I'd created using trace bitmap, and Inkscape has stopped working!

....please would you explain what "make multiple copies of the path " is? thanks...new to Inkscape


I do see,though, that once we select OBJECT TO PATH, we need to then select the 2nd tool "edit path by nodes" and the paths are highlighted....

Lazur
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Re: How to isolate components of traced bitmap

Postby Lazur » Sat Aug 02, 2014 9:34 pm

Hello, have you read the manual?

Multiple scans result in a group of paths above eachother, single scan results in one path.
Probably your traced result was made with the latter, and, the freeze is the result of performance issues.
Too much nodes to handle at once can be the problem, to overcome it you can either
use smaller images with less details or
try the 64bit build on a 64 bit windows os.

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Xav
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Re: How to isolate components of traced bitmap

Postby Xav » Fri Aug 08, 2014 9:21 pm

Jopublick wrote:Hello, I used break apart on a greyscale bitmap that I'd created using trace bitmap, and Inkscape has stopped working!

....please would you explain what "make multiple copies of the path " is? thanks...new to Inkscape


If you're trying the method I described above, then I just meant using copy & paste (or duplicate) to create additional copies of the path. In this case I was referring to a path created using the "single scan" mode of the Trace Bitmap dialog. Consider a simple traced bitmap that has three distinct sections that you want to separate:

1) Duplicate the path twice to create three identical paths.
2) Roughly draw a polygon over the top of the first part.
3) Select the polygon and the topmost path, then use Path > Intersection to cut the top path down to just the first part.
4) Repeat steps 2 & 3 for the remaining two parts.

You should end up with three separate paths, but when your "parts" have lots of nodes, holes or are made up of separate bits, this method can be a lot easier and faster than node editing, and produce a better result than "break apart".
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