Duplicated, selected out background and feathered selection heavily.
Created a mask from the selection and multiplied the background to intensify it, and dropped the brightness a tad.
Followed wulf's DIY highpass filter by duplicating the bottom layer twice, blurring copy 1 with a guassian radius of 15ish, setting to grain extract, merging down, setting to overlay, merging down.
Then I cropped it to square, rotated, and added a vignette by duplicating it, creating a heavily blurred circular mask on the top later, darkening the top layer heavily, setting the layer to multiply, and merging it all down.