Inkscape.org
Beginners' Questions Tracing Trouble - No Preview
  1. #1
    JPx JPx @JPx

    Hi,

    I'm trying to trace the outline of this imported image however the preview window in trace bitmap will either show nothing or it shows the centre markings of the image I want to trace. 

    I follow all the instructions to the letter ie. Import Image > Resize > Place on Artboard > Select Path - Trace BitMap > Select Image and nothing even after hitting Update and Live Preview. 

    Can you please help me work out what is wrong.

    https://photos.app.goo.gl/CLMe65Pa8EiVLLoM7

    Thanks

     

  2. #2
    brynn brynn @brynn

    Welcome JPx!

    The status bar in your screenshot shows that you have selected a Path.  That means it's already a vector path, and therefore does not need to be traced.

    I'm not sure, but I'm guessing you want to trace those....they look like they might be clothing pattern pieces?  It could be you just have the wrong thing selected.  Or it could be they are already traced, and that's what you selected.

    The trace results come out right on top of the original image.  So sometimes it looks like nothing happened when you traced.  I know when I use Trace Bitmap, I always have to drag my original image out of the way, to see my trace results.

    But anyway, keep an eye on the status bar  🙂

  3. #3
    JPx JPx @JPx

    Hi,

    thankyou for the prompt response! 

    I'm still confused so think I should explain in more detail what I did to get to this point.

    After a few attempts I'd thought I'd worked out how to trace the image successfully [image] until I went to move it and the bottom line wasn't attached [another question for another day!] so I opened a new page to have another go at tracing the image incase the issue was my bad tracing technique. I followed the exact same regime as before ie. importing the JPG from my computer onto the new page.

    https://photos.app.goo.gl/HL7GBVDdH5swfGaVA

    Thinking it might be an issue with opening a 'new' page, I shut the site down, reopening to no avail, I still get the same blank preview window.

    I'm hoping it's something in the proceedure I've overlooked or something I am unaware of.

    Thanks

  4. #4
    brynn brynn @brynn

    Could you import the image, save the file as SVG and share the file with us?  I can't tell anything from your 2nd screenshot because nothing is selected.  But with the SVG file, we could investigate for ourselves.

    Are you trying to trace the lines on the left?  Or the part on the right side, that looks like pattern pieces?

  5. #5
    JPx JPx @JPx

    Thanks Brynn - hoping this works.

    https://drive.google.com/file/d/1VmB1c_ax3BahSgfVvA94YU45BKpZvzju/view?usp=sharing

    The lines on the left from the previous message/link are the tracing from the pattern piece on the right.

  6. #6
    JPx JPx @JPx

    I did a couple of things which in combination has possibly fixed my problem.  

    1. changed the name of the file I was importing 

    2. clicked on the Gray button in multiple scans

    http://photos.app.goo.gl/4meoiuNBYz4ctSSJ7

    I am now able to drag my orignal image out of the way however I am curious to know if changing the name of the file made an actual difference and what does 'multiple scans: creates a group of paths' mean?

    Thankyou for your time

     

  7. #7
    brynn brynn @brynn
    *

    So in your 2nd screenshot, where the pattern pieces are on the right, and there is the solid line on the left, did you trace that with the Pen tool?

    Now I understand what the problem is.  The problem is that your original image is not really in the kind of condition where you can achieve a good trace, using auto trace.  The best approach for tracing that image is to trace it by hand, with the Pen tool.  Because your human eye can make out the proper outline.  Inkscape's "eye" can't figure it out.

    Changing the file name did not have anything to do with it.  When you switched to the Grays button, it did 2 things.  First, it set up a multiple scan.  And you need just a single scan.  But 2nd, the reason you could see something in the preview window, is because that option looks only at shades of gray, which is what your image is made of.  The problem is that Inkscape traces exactly what it "sees".  The attachment shows my result from tracing with the Grays option.

    The kind of image which can give the best trace result would be a heavy, solid, black line on a solid white or solid colored background.

    So as I said earlier, tracing by hand using the Pen tool, would be the best approach for that kind of image.

  8. #8
    JPx JPx @JPx

    Thanks brynn and apologies for the late response - think we're on different time zones.

    At the end of the day I want to have the pattern piece as a tiled pdf which can be printed by others. Before I can do anything with the pattern in Inkscape I thought I had to trace the imported image as a bitmap to change it from a raster to vector?!  

  9. #9
    brynn brynn @brynn

    Um, it might not be the time zones.  I tend to keep strange hours!

    Hhmm....  What do you want others to be able to do with the PDF?  Do you want them to be able to cut out whatever you send them?  Or do you just want to send them the pattern, and they can do whatever they want with it?

    I mean, you could simply scan the pattern pieces into your computer, and send them separately (in a multi-page PDF) and they could do whatever they want with them.  But if you want to send them a cuttable file, you'll need to trace the pattern by hand (using Pen tool in Inkscape).  I don't know of any trace engine which can pick out the cutting line from your image.

    Maybe if you could take a marker, a heavy marker, and trace over the line before you scan it in (or however you achieved the image, I'm not sure) (or maybe it's a photo?).  Then possibly Trace Bitmap could be configured to be able to "see it" well enough to create a proper path.  I'm not positive that would work, but it might.  Oh, or maybe if the pattern was a darker color, that might work too.  Like bright red or black or dark blue?  I'd have to have one of those things, and play with it for a bit, to be sure.

    Or else, in your 2nd screenshot, you said the line on the left is a tracing.  I'm not clear if you mean tracing by hand, or by Inkscape Pen tool.  But that's the kind of line that Inkscape needs, for Trace Bitmap.

  10. #10
    JPx JPx @JPx

    You've been very helpful however I was hoping that the scanned image I have [created in photoshop and imported from my computer] could be traced as-is in Inkscape and then saved as a pdf.

     

  11. #11
    brynn brynn @brynn

    Well we've sort of been over that.  It CAN be traced and saved as PDF.  But it won't be a cutting line.  I showed you what auto-tracing that image creates - not a single cutting line or path, but a mess of paths.  The auto-trace engine cannot pick out the cutting line from your image.  No trace engine that I know of could do that.  You could use Inkscape's Pen tool, and your own eyes, to see the cutting line and draw it.

    In your 2nd message above (message #3) you gave a link to a screenshot where there's an image on the left - a single, solid, black line.  THAT is perfect for any auto-trace engine to be able to trace (although you would need to use the Centerline Trace extension, in Inkscape).

    So if you want people who open the PDF file to be able to create a cutting line by auto-tracing it, you need the solid black line.  If you want them to trace it by hand (either using a real pen/pencil or Inkscape's Pen or Pencil) you could send them the image.