Yes it's possible.
Add an adjustment layer to an image, and select the mask thumbnail in the layers panel. It will be highlighted with a white outline showing that it is selected.
Choose the gradient tool, set a black to white gradient from the drop down

- Click and drag on the main image window, and the gradient will be applied to the selected mask.

Note: you can also use this method to apply a gradient to any layer mask, not just adjustment layer masks. You can also paint with brushes directly on a layer mask to edit it, you aren't just limited to using the gradient tool. Painting in white makes the mask opaque, painting in black makes the mask transparent, painting in shades of grey makes the mask semi-transparent.
Answer from Billy Kerr on Stack ExchangeYes it's possible.
Add an adjustment layer to an image, and select the mask thumbnail in the layers panel. It will be highlighted with a white outline showing that it is selected.
Choose the gradient tool, set a black to white gradient from the drop down

- Click and drag on the main image window, and the gradient will be applied to the selected mask.

Note: you can also use this method to apply a gradient to any layer mask, not just adjustment layer masks. You can also paint with brushes directly on a layer mask to edit it, you aren't just limited to using the gradient tool. Painting in white makes the mask opaque, painting in black makes the mask transparent, painting in shades of grey makes the mask semi-transparent.
Grab the Gradient Tool...
.... set the Gradient to Black -> White, or Black -> Transparent..
....then click-drag on the layer mask in the direction you want the gradient to follow.
As far as I'm aware, there's no "automated" way to fill any layer mask (on an adjustment layer or any other layer type) with a gradient. It always required the user to click-drag with the Gradient Tool.
Videos
Hi folks, apoligize this is Inkscape specific, but i believe the mechanisms are the same. i am a dummy with image editing. I am having a big headache with this. Totally new to image editing.
I want to accomplish this: I want to edit a background image for my website. The original image is very bright, I want to make the left side of it darker (less brightness), and the right side stays the same brightness. So I can overlay white text on top of the image on the left half. So I want to add a gradient layer to my image.
I am just totally new to this, watched a bunch of youtube videos. This is where I am at so far:
I created a gradient layer, and selected both of that and the original image, and set mask. However, the end result is so opaque. What did I do wrong? How can I get what I actually wanted?
Is there a reason why this happens automatically?
Hello!
I was working on something and remembered I could use gradients in layer masks to make the fade off look really nice and smooth. However, when I am trying to do the gradient in the layer mask, absolutely nothing happens. I attached a video for reference. Am I doing something wrong? Help would be very much appreciated. Thank you!
Video: https://imgur.com/a/EPwoRBr
Hi, I'm new to CSP (coming from Photoshop). CSP won't let me apply a gradient to a layer mask to make the layer gradient-transparent. Using the gradient tool on the layer make doesn't show any gradient. Is there a different way to do this, or am I missing a step or setting? Thank you in advance!