Variable Blur Scrim

About this pattern

Text over photography usually gets a flat dark slab underneath it, which solves legibility by throwing away the image. A progressive blur solves it by degrading the picture gradually instead, and the reason so few are convincing is that almost everyone builds the wrong thing: a single uniformly blurred layer faded in with a gradient mask. That fades the blur's OPACITY rather than its radius, so through the half-transparent region the sharp original shows through its own blur as a ghost — visible immediately once you know to look for it. A real ramp is a stack of layers at increasing radii, each masked to its own band, so that whatever gets blurred twice was already blurred once; because backdrop-filter reads everything painted behind it, including the shallower layers, the radii compound rather than compete. Two details finish it. The radii double rather than stepping evenly, because perceived blur is roughly logarithmic and a linear ramp reads as a jump near the sharp end followed by almost no change. And each band's mask spans about three band-widths with four stops, so it overlaps its neighbours — abutting masks leave a hairline seam at every boundary, and a stack of faint horizontal lines is the clearest giveaway that a scrim was constructed rather than photographed. The darkening stays in one separate gradient, since folding it into the layers multiplies it by the layer count and crushes the bottom edge to black.