PhotoShop Blur Filters

[T Paul]

PhotoShop has several blur tools and some are worth using and others probably should be avoided.

Possible Uses:

• soften portions of an image
  create dreamy portraits
  blur backgrounds to draw attention to a subject in the foreground
  create depth of field in a photo by selective blurring
  eliminate dust
  soften print texture and film grain
  minimize moiré effect
  add a creative flare to your images
  add movement to an image
  soften distracting elements
  clear up skin on portraits…create that glamour look
  convert an image to line art

Blur tool
Very straightforward to use, but has no controls or preview.

More Blur
Simply increases the amount of blur applied and is just as uncontrollable and undesirable as the blur filter as it has no controls or preview.

Radial Blur
Adds a creative flare to your images, but beware as this is a very memory intensive filter. To give a swirl or rotational motion effect, first select a portion of the image then apply the filter. This filter is a fun one to use when creating backgrounds or adding emphasis to an object.

Gaussian Blur
The powerhouse of the blur tools. Gaussian Blur is a real simple tool with a single control and real-time preview window. Using it, you are able to control the amount of blur applied very precisely and dramatically transform your photo. The blur tool will blur the pixels that you are selecting. Note this tool does not have a threshold so if you keep the mouse held down it will keep blurring.

Tip
If you are using the blur tool and you need to use the sharpen tool you can press Alt to switch to the sharpen tool temporarily. This works with the sharpen tool also.

Smart Blur
What does Smart Blur do? It smoothes out grain and noise patterns between edges without adversely affecting image sharpness or fine detail. Basically Smart Blur only blurs areas that are of similar color. Image color, sharpness & important detail are therefore retained, and noise & grain are virtually eliminated.

Motion Blur
A great way to add movement to an image.

Tip: Rotate the angle of the motion blur filter to match the direction of your subject.

Got some of your own creative uses for the blur filters, please add them to this thread!

[Andrew B.]

Some other uses of blur are:

1. If you composite an image and anti-alias is not adequate, or for some other reason the edge is too sharp. You can blur the edge. This can be done by selecting the added image and modifying the selection it to only select the border. Or, you can use the blur tool around the edge by hand.

2. Luminosity masks, contrast masks, etc. These are all helped by applying a gaussian blur.

[DannyRaphael]

Alternatives to Gaussian Blur:
* Noise > Median: Retains color saturation better
* Noise > Dust and Scratches: Same as Median, plus has a Threshold setting = more options

Comments:

* Why bother with Blur? You have no idea what it will do and no control over it.

* Blur More: Ditto. (The same applies for filters Sharpen and Sharpen More)

* Smart Blur > Normal: Sometimes leaves edges a bit ragged. To smoothe edges a bit, apply Stylize > Diffuse > Anisotropic, then Fade > Diffuse to adjust the application.

* Smart Blur > Edge Only: Renders an image composed of major edges. Follow it with an Image > Adjustments > Invert command to render black lines on a white background.

Then apply Stylize > Diffuse > Anisotropic, then Fade > Diffuse to tone down the line softening.

* To create a background for your image that contains the colors in your image, duplicate the Background layer and apply Motion blur (at a non-vertical or horizontal angle) with a large amount of blur. Merge this layer with the original with a Layer mask.

* Gaussian Blur and Quick Masks: Applying (say) a 2 pixel Gaussian Blur while in Quick Mask mode yields the same results as Select > Feather (2 pixels) with one major advantage. You can actually SEE the impact of the feathering on the mask as you tweak the Gblur slider assuming the mask opacity is high enough in Quick Mask mode to visually distinguish the effect of radius changes.

Along the same lines (and this is a bit off topic overall, but since we're here anyway...), Filter > Other > Minimum (2 pixels) in Quick Mask Mode is the functional equivalent of Select > Modify Selection > Expand 2 pixels; Other > Maximum (2 pixels) = Modify Selection > Contract 2 pixels. Using the Preview option on these filters gives you the ability to, well, preview the effect of moving the radius slider before applying the selection modification.

~Happy Blurring~
Danny

[T Paul]

You can easily convert an image into a line drawing using the Smart Blur filter.

To do so, open your image and choose Filter, Blur, Smart Blur. The resulting Smart Blur dialog box has four settings: Radius, Threshold, Quality, and Mode. Set the Quality to High and Mode to Edge Only. Then, set Radius to 2 or 3 and Threshold to between 35 and 50. Use the Preview window to examine the filter effects and change the Radius or Threshold setting to optimize the result. Then, click OK.

As you'll notice, the filter creates white lines on a black background. To set the image to black lines on a white background, choose Image, Adjust, Invert.

To thicken each line to achieve an effect much like a wood block stamp, choose Filter, Other, Minimum. Then, you enter 2 or 3 in the text field and click OK.

Another great thread about this is locate here:
Line Art Using Smart Blur

[T Paul]

The Blur tool is especially useful on files that have a lot of small, random dust specks on a variety of backgrounds.

1. Open your file and add a new layer
2. Activate the Blur tool and set its options to 100% Pressure and Use All Layers. To eradicate light specks, set the Blur tool's Blending Mode to Darken; to make dark specks disappear, set the Blending Mode to Lighten.
3. Zoom in to 100% or 200% view.
4. Set the Blur tool's size to approximately match the size of the dust speck.
5. Click and hold the Blur tool over the dust spot. The longer you hold down the mouse button, the more the dust will be blurred into oblivion.

NOTE
Be careful not to over blur the dust because that will soften the image area so much that soft blobs will begin to appear. There is a fine balance between just right and too much blurring—with a bit of practice you'll develop an eye for the right amount of blurring.

TIP
Matching the size of the brush to the size of the dust speck to be removed and using a hard-edged brush ensures that you don't soften the grain of the image surrounding the dust speck.

Use the keyboard shortcuts to control the size of the brushes:
Left bracket ([) decreases brush size.
Right bracket (]) increases brush size.
Using the Shift key with either bracket adjusts the brush hardness in 25% increments.

[Ed_L]

Great thread T. I like to use gaussian blur on alpha channels which I have saved a selection to. Instead of using feathering, I save the selection as an alpha channel, then I can use gaussian blur to soften the edges of the selection as many times as I want without having to remake the selection. If I get lucky, I get it right the first time , but when unlucky, this comes in very handy.

Ed

[T Paul]

Smart Blur is not always the world's best noise reduction filter. But for some pictures, nothing works better and easier. It's simply another useful option. Smart Blur can be really good for correcting ruddy, blotchy skin tones in high ISO pictures. Low radius values (0.5 to 0.8) will be necessary to retain natural looking skin textures. If close-up fine detail appears degraded after applying the Smart Blur filter, lower threshold values to around 15 or so.