Radial gradient

A tool in Lightroom and some other photo editing applications. The centre of the gradient area is left unedited, and the editing adjustment you make are blended in progressively towards the edges of the picture. You can change the size of the gradient, its position and how progressively the adjustments are blended in. The gradient can also be inverted so that your adjustments are applied in the centre and areas outside the gradient area are unaltered.