Re:Learning Lens Blur Fields
by mcdeltat on Monday September 15, 2025 @05:23AM
(#45247732)
I always wondered why lens blur is considered hard computationally. Lens mathematics seems pretty well understood given that we can create quite complex lens designs with incredible performance (take a look at modern DSLR lenses, they often have 10+ elements). And in general blurs (e.g. Gaussian) are not complex algorithms.
Are there situations where lens blurs are easier/harder? I heard for 2D images it's hard to add blur - seems true because most smartphone artificial bokeh is horrible despite significant effort there. Presumably because depth information is missing? Is it easier for raytraced 3D renders?
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Lens blur without a depth map is an ill-posed problem. So the computation goes into faking depth information somehow.
It is exactly that. Blur is a function of depth related to the focal distance, so without depth you cannot "blur".
Re:Learning Lens Blur Fields
by AlecSchueler on Monday September 15, 2025 @05:51AM
(#45247913)
You've got it exactly. It's difficult to recalculate depth when you only have two dimensions. In a 3D environment it's as simple as you would expect.