P: Simulating a center-radiating "linear" gradient

Forum|Forum|2 years ago
July 30, 2023
3 replies
1605 views

Is there any way in LrC to create a linear gradient that radiates out equally from the centre rather than always graduating from the top or bottom?

ON1 Photo RAW has this feature and it was a really useful way to accurately mask a section of the image. I suppose one could replicate it with a very large flat radial gradient but I wondered if there was a keyboard modifier that did this to the LR linear gradient that I'm missing or is this something for the next upgrade?

Correct answer johnrellis

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"a linear gradient that radiates out equally from the centre rather than always graduating from the top or bottom"

Here's a preset Symmetric Linear Gradient that implements Rikk's interpretation (which makes most sense to me now):

It's flat to 6 parts out of 10,000 (0.06%).

Rikk Flohr_Photography

Community Manager

@johnrellis I've been doing this adjustment as a preset for years. I originally built as series of these to simulate the Singh Ray Reverse Graduated filters. Editing the preset by hand allows you to be very precise in your transition between the two constituent linear gradients. https://singh-ray.com/equipment-technique/nd-filters/the-reverse-graduated-nd-filter/

Rikk Flohr: Adobe Photography Org

johnrellis

Legend

@Rikk Flohr: Photography, the Symmetric Linear Gradient preset I posted shouldn't require manual editing. You can drag it anywhere and independently adjust the inner lines (where the preset starts to fade out) and the outer lines (where the preset completely fades out).

I uses a very wide radial gradient that is very nearly linear (6 pixels out of 10,000). It took some careful discovery of the parameters of that gradient, since the LR/ACR rendering engine fails to render extremely wide radial gradients.

johnrellis

Legend

"I suppose one could replicate it with a very large flat radial gradient"

It's not clear to me how what you're describing differs from a radial-gradient mask? Are you asking for a quick way to create a radial gradient that's perfectly centered in the photo extending to the edges? I've attached a preset Centered Radial Gradient that does that.

Centered_Radial_Gradient.zip