Global discrete gradient-norm denoising
= Global discrete gradient-norm denoising
{title2=$\min_u\{\alpha\|Au\|_2+\tfrac12\|u-g\|_2^2\}$}
For a discrete <image signal> operator $A$, minimize $\alpha\|Au\|_2+\tfrac12\|u-g\|_2^2$ with one <Euclidean norm> on the full <gradient> array. This differs from <discrete isotropic total variation>, which sums pixelwise Euclidean lengths. The global <norm>'s dual ball is a single ball; its <convex projection> normalizes the whole vector array.