Gaussian Blur on texture

what is width and height here?
If my image size 720X480 does it mean width is 720 and height is 480.
Or is it the size of the window

I got answer for the above question.
But now I have another question, in the earlier example of a fragment shader it uses 7x1 matrix.
What if I want to use 7x7 matrix?

Hi Vexator I have one question, in the earlier example of a fragment shader it uses 7x1 matrix.
What if I want to use 7x7 matrix? Do I have to use a nested loop with u_Scale = vec2(1.0/width, 1.0/height )