Effect of beam-weighting of wavelet coefficients. a: step-like spatial variation of s (solid black line). The filled black area represents its convolution with the instrumental beam (dashed red line). b: effective spatial variation of s. The blue and red lines represent the absolute value of the positive and negative parts of the wavelet kernel, respectively. The envelopes of the shaded areas coincide with the convolution of the instrumental beam with the support of the positive and negative parts of the kernel.