*Your images need to be the same size in order for this to work.
To start you are going to need 2 images. One of your main subject, and one of what you are going to use with the displacement map.
I use textures for my displacement map, and for this tutorial I am using an image of some tile I took.
Open up your subject in Photoshop.
(Convert the images to 8-bit if it is a 16-bit image by going to Image->Modes->8Bit/Channels)
We don't want to overwrite or originals by accident, so lets duplicate the image by going to Image->Duplicate
With the copy of the image go to Filters->Blur->Guassian Blur
I used a radius of 27 pixels.
Your image should look similar to this.
Now save this image as a PSD file.
Open up your texture.
Go to Filters->Distort->Displace
I used the following settings:
Horizontal Scale: 95
Vertical Scale: 95
Displacement Map: Stretch to Fit
Undefined Areas: Wrap Around
You will now be prompted to open your displacement map.
This is the blurred image you just saved as a PSD file.
In your layers palette, right click on the background layer and select "Layer From Background ..."
This will let us edit/adjust the background if needed later on. A background layer has limitations that a layer does not. By converting the background to a layer, we are able to manipulate it in more ways than if it were just a background.
Now we need to copy the original image of our subject/model into the displacement image.
Lets organize our two images (the original and our new displacement map) side-by-side. Then select your Move tool. While holding down the shift key click on your original image and drag it on top of your displacement image.
Holding down the shift key automatically aligns the two new image layers up.
If you haven't been saving along the way, this is definitely a good time. Be sure to save this image as a PSD so your layers stay adjustable.
This is the time to play. Change the blending modes on the layers, change opacity, just keep playing until you find something you really like. I am sure you are going to come across some amazing combos. Also, you don't need to limit yourself to just these layers, add more if you want.
I am going to add a 2nd part to this tutorial on using the quick mask to keep detail in parts of your image.
You can ask questions or discuss this tutorial on Digital Grin.