Automatic tracing of uploaded photos is one important feature coming to clker.com . I will describe briefly how far we reached, and what I hope to accomplish within the next few days until it is released.
First off, let me outline the benefits and draw backs of auto tracing. The obvious biggest benefit is no human work is put into the segmentation and vectorization process. However, it has been proven in lots of domains that when two humans segment the same picture their result will have approx. 80-85% common areas. This means that humans will disagree about the segmentation of the same image in about 15% of the image itself. That’s because the way our brain interprets an image depends on every persons own understanding and knowledge of the contents image, and that can vary a lot. Even when the human segmentation results are in a very specific context like brain segmentation, and done by radiologists the comparison between the similarity between their results was between 83-87% using a similarity measure similar to the Jaccard index. So the disadvantage of automatic segmentation is that if we were able to reach the perfect algorithm to segment an image, the user will always have around 15-20% disagreement with its result.
The results that I will show here are based on this helicopter image (also shown on the top). There are several parameters used as the inputs to the segmentation program. Most of those will either be selected by us to provide good results in average, or passed through clker’s interface in a more humanly understandable fashion. The image was reduced in size to approximately 1 mega pixel before processing.
Those two images are direct output of the vectorizing program without any modifications. The difference between them is the number of regions in each. In the image on the right, we attempted to reduce the number of resulting segments, which can help greatly especially if the user plans on editing the image after.
To see how hard it is to produce a clip art out of this segmentation, I tried to edit the image on the left (the one with larger number of segments) and delete all the sky regions. It took me around a minute to do so, just select and delete and the result is below:
However, some people will not perceive this image as a clip art. One reason is the lack of hard outlines around the object when compared to an image like the deck officer here . The other reason is the number of regions is way smaller. I will be spending the next couple of days trying to get some borders up and hopefully we’ll get some good results.
I imagine now two ways to have this feature up. The first one once you upload a raster image, clker will work on vectorizing it then you will get an email with a link to the vectorized version. The other way (which will come later in time) will be requesting a custom segmentation with the ability to adjust some of the parameters like for example requesting smaller number of regions, or different types of color enhancement including equalization, white balance correction ..etc.
Hopefully this will be running on clker by Monday next week.