Intensity change after filtering this image?
For binary images, the filter kernel you have is looking for a $0 \rightarrow 1$ edge in the North-East direction.  Your image raster only has one place where such an edge exists (in the bottom left / South-West corner).

The sign of the output means that the edge is a $1 \rightarrow 0$ edge transition rather than a $0 \rightarrow 1$ transition.