Is It My Memory, Or Has The Stacked Layout (for Galleries) Changed In Any Way?

I'm seeing padded areas on some of my pictures when using Stacked in galleries.  Only noticed it this morning after upgrading to 4.5.4 but it could be coincidence or just bad memory.  Seems to affect mainly vertical orientation images.

Has anything inadvertently changed with Stacked or am I remembering it wrong?   I've been tinkering with layouts quite a lot this past week and never noticed the 'empty' areas around images before (not the spacing between)

It hasn't changed. The image is too small to fill the container. You can either edit the photo display settings and make the row width smaller, or increase the size of the "Small" photo in Settings -> Photo Settings. Changing the sizes of the photo settings won't change existing photos.

Thanks Tim but I'm a bit confused by how these numbers work.

I have Stacked galleries set to use the *Large* photo.  Large size is set to 1600px max width and height, so vertical orientation picture would end up about 1065 pixels across, width-ways.

Yet if I have Stacked layout row width set to anything more than 353px I get the empty padding on vertical pictures.

The large photo is used for viewing enlarged with purchase options. The grid of thumbnails use the "small" photo. 

Fair enough, I guess this is where my confusion is coming from....