Inside/Outside Matting

There are limits for bluescreen matting. In mose case, we need a more general way, which can:

1，No special limits in background
2，Support semitransparent.
3，Easy to understand and some kind of 'automatical'.

The inside/outside matting match all 3 items, that means it can be applied on most photos. The inside edge of object means a selection inside the object and close to its real edge. And the outside edge means selection cover all pixels of the object and close to its edge. The area between inside and outside is the edge of object and the semitransparent part. The programe will calculate the real mask by the user specified inside/outside edge.

The users will save their time, because the inside/outside edge need not to be very precision. The final quality of mattes depend on how accurate the program 'guess' the area between inside/outside edge.

What is the main reason cause the inaccurate 'guess' which brings defects in result?

There are defects because the program can not tell the right foreground color and background color when it judgement a pixel in interspace. The orginal photo is a composed one, the matting work is an inverse caculate processing, To know the what the subject opacity should be, it need to know the real background color, the read foreground color, or two of these 3 variables. Now, the real foreground and background can be misjudgement, so the opacity could be wrong, and that caused the defects.

The following samples may cause lots of defects for program:

1,It's hard to be distinguished for even human eyes.

 

2,The program guess the color from inside and outside, if there are much changes in interspace, the program may make mistake.

As above, the inside edge goes through the skin, the program will suppose the foreground color in '?' area is skin color. Actually, it is black. In this case, the foreground injector is need to inject some hair samples into inside.