and I want to convert it to vector image. I have Inkscape app and only method I know is tracing bitmap, but when image is very complex and drawn by hand, my vector image has many many points and sometimes the app completely freezes. Also, tracing converts sharp edges to round edges. So the converted image differs from the original. Is there any different technique for doing this. I know there has to be something.
You can get good results in Inkscape with Trace Bitmap, however that image needs some cleaning up in a raster image editor first.
What you could do is open it in GIMP/Photoshop etc, desaturate it, do a levels adjustment to increase the contrast, and paint out all the shadows around the outside with a white brush.
Auto tracing works best when you have a contrasty image, with no shading. Also there's an option to switch off smoothing in the Trace Bitmap dialog in Inkscape.
Obviously I did this pretty quickly just as an example, but if you take a bit more care to clean up the raster image first, you'll get better results.
Generally, you would redraw it. You could try to trace it, but i wouldn't bother with that because odds are that would not give you what you want anyway. Complete workflow would look like this:
- Scan image in a flatbed scanner.
Open in Photoshop.
- Cleanup noise and blemishes.
- Make background white with curves or levels
- make black actually black
- (optional) make image 1 channel
- import in illustrator, put it on a layer and make that layer template
- Manually draw points on top of said image
There no shame in using raster images. You should be aware of that. A high quality, high ppi raster image is exceptionally useful in many instances. That particular image is problematic due to the low contrast background and vignetting. But a clean drawing scanned to a clean image would be more than sufficient for many methods of output.
If you really want vector, then Joojaa is correct in his answer.. redrawing is the best method.
With experience you learn to draw with vector conversion in mind - often using less detail in the drawing knowing you'll add detail in the vector artwork. It sort of gets like tattooing... you draw basic shapes, scan and manually trace those, then add all your detail in the vector application rather than by hand. This saves doing the work twice.
Barring that, tracing is pretty much the only other option, short of hiring someone to do it for you.
Different software will trace differently. You may need to experiment with different auto-trace features in various application to find one which you feel works best for you. In general, you scan as large as possible, use a raster editor to make certain the contract of the scan is high, eliminating any subtle grays and making certain blacks are black.
Essentially you have to learn to scan and adjust for the trace... most tracing features will work best with art as large as possible allowing them to see more detail.
There's no simple solution overall. I, personally, would not be able to do anything with your sample image other than redraw it due to the background and low contrast.
I'd give it a crack with a combination of Paint.Net and then Inkscape.
Open in paint, then cut out the area that you want to include in the image, probably just a circle, then make it black and white from the Adjustments menu. Save this as a lossless file.
Open inkscape, import the file. Right click on it and choose Trace Bitmap.
From here you will get some options for thresholds, I suspect Brightness cutoff will be the most effective, something around 0.65 would probably be a good start.
If you're missing bits up the brigtness. If you have too much noise lower it.
If not all of the image is good then you can always do 2 or 3. Then use edit paths to remove bits from ones that you don't like and group the result together.
HOWEVER, this tool does create lots of nodes, and as a result a bigger file unless you clean it up. Choosing to trace the image using the bezier tool will create a far smaller file.
I often vectorize ink scratchings, but I always scan them before colorizing.
Then, on scanning, I can select the resolution (600, 300, 200, 100, 50 dpi).
For vectorizing the file, I convert the PNG into PNM, because then I can vectorize it with
potrace -s --group -o $name.svg $name.pnm
by script. Potrace itself has plenty of options to experiment with. Maybe you have a look at them.