Photoshop Tutorials: Add A Realistic Water Reflection
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Step 8: Apply The "Gaussian Blur" Filter To The Lines
Before we can use our black and white lines as water ripples , we need to smooth them out and create nice, smooth transitions between them. To do that, go up to the Filter menu once again, choose Blur, and then choose Gaussian Blur, which brings up the "Gaussian Blur" dialog box. Keep an eye on your image and drag the slider at the bottom of the dialog box to increase the Radius value until the lines have a very soft edge to them. I'm using a small image for this tutorial, so for me, a Radius value of about 4 pixels works well. If you're using a larger, high resolution image, you'll need to set yours to a higher value:

Click OK to exit out of the dialog box and apply the blur to the lines.
Step 9: Duplicate The Lines Layer As A New Document
We're going to create a brand new document out of our lines layer, which we'll then use as our displacement map for our water ripples . With the lines layer selected, go up to the Layer menu at the top of the screen and select Duplicate Layer, which brings up the "Duplicate Layer" dialog box. In the "Destination" options, click on the down-pointing arrow to the right of the Document option and set it to New, which will create a new Photoshop document out of our layer:

Click OK to exit out of the dialog box, and your layer will open up in a new document on the screen.
Step 10: Save The New Document And Close Out Of It
This new document that we've created is going to become our displacement map, but before we can use it, we need to save it. We're also going to close out of it after we've saved it, since we won't need it open anymore, and the easiest way to accomplish both of those tasks is to simply close out of the document. When you try to close out of it, Photoshop will as you if you want to save the document before closing it. Click Yes:

Photoshop will bring up the Save As dialog box. You can name your new document anything you like. I'm going to name mine "water-ripples". Make sure you save it as a Photoshop .PSD file, since those are the only files that Photoshop can use as a displacement map. You'll probably want to save the document to your Desktop, since we'll need to find it again in a moment.
Step 11: Delete The Lines Layer
Now that we've used our black and white lines to create the file we'll be using as our displacement map, we can get rid of it. To do that, simply click on it and drag it down onto the Trash Bin icon at the bottom of the Layers palette:

Step 12: Merge The Two Layers Onto A New Layer
Before we can add use our displacement map, we need to merge our two image layers onto a new layer above them. To do that, with "Layer 1" selected, use the keyboard shortcut Shift+Ctrl+Alt+E (Win) / Shift+Command+Option+E (Mac). Nothing will appear to have happened in the document, but if we look in the Layers palette, we can see that both layers have been merged onto a new layer at the top:
