Displacement Map
I’m using a photo I downloaded from Pexels.Com and made it tileable in GIMP
I first desaturate the image by going to Colors > Desaturate > Desaturate
I change the mode to Lightness HSL
Next, I distort the image by going to Filters > Distorts > Shift and use a Shift option of 5
I then add some blur by going to Filters > Blur > Gaussian Blur and change the blur to around 10
I then adjust the contrast by going to Colors > Curves and make the blacks darker and the whites lighter
I can now export the displacement map
Blender
In Blender, I subdivide a plane and apply the original image as the base color
Under the Materials tab, in the Settings panel, I change the Displacement to “Displacement and Bump”
I import the displacement map (changing the color space to Non-Color) and connect it to a Displacement node which is then connected to the Material Output
I add a Displace modifier and open the displacement map
I decrease the Strength
I change the coordinates to UV and choose the default UV map
I also change the direction to RGB to XYZ