How can I create something like this in Photoshop?
Have two versions of a photo in 2 layers:
- bottom layer = the photo as is
- top layer = the photo with heavy blur, maybe darkened, too
You can simply make selections with polygonal lasso tool and delete pieces of the top layer. Better idea would be to insert a layer mask and make there those areas black which should vanish, white=stay as is. Layer masks are recommended, because they can be edited removed and redone without destroying the image.
NOTE1: Masking like this needs a photo which has a good contrast between the background and the foreground. Otherwise the result is messy.
The blurred version is 25% darker. It has a layer mask.The mask was originally white, but I painted some black to it (=made selections in the mask and painted with black those selections, the mask icon was clicked at first in the layers panel to change the focus to the mask instead of the image)
Complex symmetric geometric shapes are easier to make in Illustrator. From there they can be pasted to Photoshop to be used to make selections or to be placed into a layer mask.
A simple pattern is made in Illustrator.
The pattern is copied and pasted to a layer in Photoshop. It was pasted as pixels and stretched a little at the same time.
Next the pattern could be used to make a selection with magic wand and to delete a part of the blurred copy. A selection was made, but nothing was deleted, only generated a layer mask to the blurred layer. It got automatically the right shape. Magic wand was used to select the black shapes.
This all can be done in Illustrator. Opacity Mask does the same as the layer mask in Photoshop.