inkscape - trace bitmap help

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redriding
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inkscape - trace bitmap help

Postby redriding » Mon Feb 20, 2012 8:15 pm

Hi, need help with something...

When I trace a bitmap I'm having trouble maintaining the original dimensions of the image - how do I maintain the size of the image from bitmap to vector?

Any help appreciated!!
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brynn
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Re: inkscape - trace bitmap help

Postby brynn » Tue Feb 21, 2012 2:25 pm

Hhhmmmm.....I'm not sure how that would happen. How much does the size change? Is it like a few pixels? Could you estimate the percentage of change? Is the result larger or smaller than the original?

If no one else has any idea about this, I would suggest attaching the image, so we can try it, and investigate.
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redriding
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Re: inkscape - trace bitmap help

Postby redriding » Tue Feb 21, 2012 8:32 pm

The size change depends on image. I'll attach a simple example (two images, the original and the traced):

original is 650.00x378.00 px
traced is 504.302x263.491 px

When the object is traced, it appears the surrounding empty space is cut out. I wish to maintain it in the final trace...

Thanks!
Attachments
testtrace2.JPG
testtrace2.JPG (89.01 KiB) Viewed 1357 times
testtrace1.JPG
testtrace1.JPG (89.34 KiB) Viewed 1357 times
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brynn
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Re: inkscape - trace bitmap help

Postby brynn » Tue Feb 21, 2012 9:11 pm

Ooohhh, I understand now.
There's a technique using trace bitmap where you can automatically have the background removed. Apparently you must have had one or both of those settings engaged, when you did the trace. Make sure that Remove background and SIOX Foreground selection options are not checked, when you do the trace.

Does that fix it?
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Xav
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Re: inkscape - trace bitmap help

Postby Xav » Wed Feb 22, 2012 12:24 am

The "Single Scan" section of the trace bitmap dialogue will always remove the background, as far as I can tell. If you want two paths (one for the "content" and one for the background area) you'll need to use the lower half of the dialogue ("Multiple Scans"). For the example image you posted I would suggest choosing "Greys", making sure that "Remove Background" is unchecked, and put the "Scans" spinbox down to a low value such as 2.

If all you want is a rectangle of the same size and shape as the original image to used as a background, there are a few alternative approaches you could take. I would just draw the background rectangle from scratch - if you enable snapping to bounding box corners then you can draw it precisely to the dimensions and location of the original image.
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brynn
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Re: inkscape - trace bitmap help

Postby brynn » Wed Feb 22, 2012 12:05 pm

The "Single Scan" section of the trace bitmap dialogue will always remove the background, as far as I can tell.

Interesting -- I was not aware of that! I'll have to do some testing, when I get back to my other computer :D
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