Alexandre Prokoudine wrote:
The howto says: "2. Cover desired foreground". Could it possibly be reworded to "Draw a closed path around object in foreground" or something like that? Same applies to hint above "SIOX" in Trace dialog.
Not really. Determining what is selected is done by using the NR::Arena stuff to render the shape over the bitmap. This way, the fill rule can be borrowed to determine what is in or out of the shape. So "covering" or "obscuring" is actually what is needed to determine what parts of the image are background and which are not. Just drawing a line around it is not enough. But there probably is a better way to say that.
I agree, the selection mechanism needs to be improved. In addition to designating what is background, we need to provide the option to designate what is foreground. This will greatly help the algorithm decide how the remaining regions attract to either foreground or background.
Look at the siox.org page, middle image, to see what I mean. The blue-marked areas are "certain background", meaning that they will certainly not be in the final image. The green-marked part is "certain foreground" meaning that it certainly will be in the final image. The regions between the two will be analyzed to determine which way they will go.
Right now, we are only marking "certain background" by selecting the part we want. Everything else is background. This PDF from the siox.org site has a lot of good examples about what this means: http://www.siox.org/downloads/tr-b-05-07.pdf
bob