Automatically Fill Circular Mask to Canvas And Automatically Centre A Mask - PSE 2020

[Chrisn N]

I would be interested to learn if ythere is a way to:

1- Automatically fill a circular mask to fill a frame

2- Automatically centre a mask to the centre of the canvas or other object.

I know how to do this manually, but it would be nice to find out if this can be done automatically to the exact pixel.

Your advice would be appreciated.

Kind regrds

Chris

[Jeff Arola · Accepted solution]

You can use the Ellipse Tool to draw out a filled circle.

Then go to Select>All, chose the Move Tool and use the Align >Center and Middle, then Select>Deselect.

[Chrisn N]

Thank you very much Jeff. This work-around works fine. Evidently, from what I can see, it's not possible to directly centre a mask on the canvas. Using this method, the mask has to be made into an object on a separate layer first, then it can be centered on the canvas using the move tool and Align Centre/Middle. Afterwards, the object can be converted back into a selection using control/left click on the layer icon. Then the object can be deleted if its not needed leaving just the circular selection.

Next I need to find out how to make a circular mask to precisely fill the canvas. Eg if my canvas is 4000 x 4000 pixels, I want the circular mask to be 4000 x 4000 pixels. 

Thanks again for all your help.

Kind regards

Chris

[Greg_S. · Accepted solution]

@Chrisn N said: 

Next I need to find out how to make a circular mask to precisely fill the canvas. Eg if my canvas is 4000 x 4000 pixels, I want the circular mask to be 4000 x 4000 pixels.

You can use the Eliptical Marquee tool and set the options to Fixed size with your 4000px x 4000px dimensions:

Click once to create your selection, move it to the center, then add your layer mask.

[Chrisn N]

Thank you very much Greg. I tried this and it works fine. It will enable me to create a selection the exact size of the canvas. The other good point is that if I move the selection with my mouse near the centre, it will automatically snap to the exact centre without any difficulty (bravo Adobe!). If it is a smaller circular selection than the size of the canvas, then I will have to use the method in Jeff's post to centre it.   

I need to understand how to do this to achieve a fisheye lens effect with photoshop elements. First I make the image and canvas an exact square, then apply the spherize filter. Then I need to use a circular mask without any feathering and copy the centre of the spherized image to a new layer. The finishing touch is to darken the outer circumference of the sphere with a blurred black inner stroke with transparency set to taste.

Thank you Jeff and Greg for all your help. 

Kind regards

Chris