我有一个位图，其中的颜色两大块相交，我想找到这两个区块的交集。

I have a bitmap where two large blocks of colors intersect, and I would like to find the intersection of these two blocks.

请注意，我不知道这两个形状的实际几何结构，因为这一切只是原始像素数据。

Note that I do not know the actual geometry of the two shapes, because this is all just raw pixel data.

有没有什么算法，我可以用它来做到这一点？

Is there any algorithm I could use to do this?

推荐答案

如果您在内存中的所有像素数据（我认为你这样做，但是这是一个主要症结点）和只有两个截然不同的颜色，所有你需要做的工作是运行水平扫描线找到的地步，从彩色X RGB改变颜色Y（请注意，您可能需要运行该扫描线几次，但在任何情况下，它比啊，不差（高度））。 一个简单的图遍历（BFS或DFS），那么将继续走你失望该行（你应该只需要3分，那么你就能够形成与方程* X + B * Y的几何线条+ C = 0 （假设它不是一个曲线））。 垂直重复该扫描线（同样​​，最坏的情况是O（宽））。找到3分，那么你就必须两条线与D * X + E * Y + F = 0。使用补偿了一点点。 GEOM，这两条线的交叉点会给你点。

If you have all the pixel data in memory (which I'd assume you do, but this is a major sticking point) and there are only two distinct colours, all you should need to do is run a horizontal scanline to find the point where RGB changes from colour X to colour Y (note that you may need to run this scanline a few times, but in any case it's no worse than O(height)). A simple graph traversal (BFS or DFS) will then continue to walk you down that line (you should only need 3 points and then you'll be able to form a geometric line with equation a*x + b*y + c = 0 (assuming it's not a curve)). Repeat this scanline vertically (again, worst case it's O(width)). Find 3 points and you'll then have two lines with d*x + e*y + f = 0. Using a little bit of comp. geom, the intersection of these two lines will give you your point.