Gaussian Blur In Photoshop – How To Enhance Your Images

This tutorial looks at using gaussian blur in Photoshop to improve your photographs and create a finished image to be proud of!

In my last tutorial, I talked about 2 specific tools used in making selections – the Magic Wand tool and the Lasso tool. Now let’s talk about the “finishing touches”. Here’s how you can make your selections look natural–not fake or manipulated, using gaussian blur as  a great way to really enhance your image.

This article is for older versions of Photoshop
(prior to CS6/CC), but the fundamentals still apply.

Purpose:  Gaussian Blur and the Refine Edge Tool smooth and soften the edge of your selection, if necessary, to help it blend in with the overall image.

  Where to find the tool:

Gaussian Blur: Select the Adjustment Layer to which you want to apply Gaussian Blur, then go to the “Filter” menu ->“Blur” -> “Gaussian Blur”.

Refine Edge: There are two places to find this.

1. In the “Options Bar” of Selection Tools, such as the Magic Wand Tool and the Lasso Tool, Photoshop has thoughtfully provided a button for quick access..

2. Select the Adjustment Layer’s Layer Mask Thumbnail to which you want to apply Refine Edge, then go to the “Select” menu -> “Refine Edge”.

Which One to Use:

Typically, I try Gaussian Blur first, because it is quick and simple. If that does not work, then I’ll use Refine Edge for more control, although it is a bit slower and more complicated.

gaussian blur photoshop

Screen shot of Photoshop's Refine Edge tool by John Watts.

 

Screen shot of Photoshop's Gaussian Blur tool examples by John Watts.

GAUSSIAN BLUR

Gaussian Blur blurs a selection edge quickly and easily, but lacks the fine-tuning available in Refine Edge

(Note – There are ways to blur more than the edge with Gaussian Blur. For simplicity’s sake, I will explaining the basic tools).

How It Works:

1. Select the Adjustment Layer to which you want to apply Gaussian Blur to its edge.

2. Go to the “Filter” menu -> “Blur” -> “Gaussian Blur”.

3. Apply an amount in the “Radius” box to get the desired results.

Here’s an Example:
In Image “A”: The sky needs to be darkened.

In Image “B”: After selecting the sky with the Magic Wand and using Levels, there’s an obvious white line on the horizon and the area above the breaking wave is hard-looking and fake.

In Image “C”: After applying Gaussian Blur, the edge softens, and the white line on the horizon disappears.

An Explanation of Some Features

There are some nifty things that you can do with the Preview Pane in the Gaussian Blur Dialog Box. (By the way, these things can also be done in the Unsharp Mask Dialog Box).

1. You can “preview” the effects of the blur in the Preview Window in the Gaussian Blur Dialogue Box by holding your cursor over it (the cursor changes to a “hand”). Then press your left mouse button–pressing it and holding it is the “before” view, releasing the mouse button is the “after” view.

2. You can also put the cursor in the Preview Window. Press and hold down the “Space” bar on your keyboard, press and hold down your left mouse button, and drag the view of the preview pane to a more desirable location.

3. With the Gaussian Blur Dialogue Box open, you can put the cursor in your actual image (a small square “box” will show up as your pointer), place it over an area that you’d like to see in the Preview Window, and left-click: Voila! That area shows up in the Preview Window.

Judge the effects of your Gaussian Blur at 25% magnification (at 300ppi) as this is the closest to “1 to 1” viewing of your image. Too much Gaussian Blur is evidenced by a “halo” effect. A good starting point would be 7.0. Increase or decrease as necessary for the desired results.

Note: Don’t forget to toggle the “Preview” option to see the effects of Gaussian Blur.

 

Screen shot of Photoshop's Refine Edge tool examples by John Watts

REFINE EDGE

The Refine Edge tool is quite powerful and gives you all sorts of options and control, but at a price. It can be slow and complicated, and has a steep learning curve.

How It Works:

1.Select the Adjustment Layer’s Layer Mask Thumbnail to which you want to apply Refine Edge.

2.Select the “Refine Edge” button or choose from the menu.

3. Apply the values needed to get the desired results.

Here’s an Example:
In Image “A”: The sky needs to be darkened.

In Image “B”: After selecting the sky with the Magic Wand and using Levels, there’s an obvious dark line on the horizon and the hill.

In Image “C”: After applying “Refine Edge”, the edge smoothes out, and the dark line on the horizon and hill disappears.

By the way, the values used in the example are:
Radius = 4.7 px
Contrast = 33%
Smooth = 17
Feather = 3.7 px
Contract / Expand = -10%.

Screen shot of Photoshop's Refine Edge tool "preview option" examples by John Watts

A Few Suggestions:

1.I have found that the first adjustment to make is “Feather”. Increase this amount to see if this does the trick. If not, then you have some experimenting to do.

2.  Be patient. You have lots of choices, and with these choices come confusion. I would suggest using one slider at a time, see what the outcome is, and go from there.

3. “Description” option: Photoshop has thoughtfully provided an instant “Help” menu for this tool within the Dialog box. Click on the Description arrow at the bottom, place your mouse cursor over the function that you want to use, and a description of that function, along with helpful speed keys, will show up at the bottom of the Dialog box.

4. “Preview” options: You can select from five “preview” options (two are shown to the right). These options help you “see” the effects of your various adjustments.

I also like to use view in the “Navigator” Palette in conjunction with these Preview options. You can see the effects of your adjustments without any “Marching Ants”.

An Explanation of Some Features

1. Radius: This determines the size of the area around the selection to be adjusted.

2. Contrast: This “sharpens” the edges and can remove “noise”.

3. Smooth: This creates a smoother outline.

4. Feather: This softens the selection edge.

5. Contract/Expand: This shrinks or enlarges the selection boundary.

Until the next time, have fun and stay well!

All text & photos / screen shots: © 2011 John Watts, Watts Digital Imaging. All rights reserved.

All written content (and most images) in these articles are copyrighted by the authors. Copyrighted material from Apogee Photo Mag should not be used elsewhere without seeking the authors permission.

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