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Posts tagged “Gaussian Blur

HOW TO USE PHOTOSHOP’S MEDIAN FILTER

Image of Great Orange Tip Butterfly
Not sure why, but last week I started playing around with the Median Filter and found out it is a pretty nifty Photoshop Filter. It is found by going to Filter -> Noise -> Medium. It works great with other filter or plugin effects and seems to be one of those overlooked older filters that Photoshop packs with its software. Using this filter basically creates an image made of softer shapes with less detail.

The funny little Great Orange Tip Butterfly photo taken at the Rainforest Exhibit at the University of Florida’s Museum used this filter. I did use Topaz Gigapixel (as the image was cropped really tight – see my How to Use Gigapixel AI as a Plug In to Photoshop blog) and Topaz Denoise AI since the crop really showed up any noise in the image. (Topaz website can be found in the sidebar at my Tidbits Blog.) Then I tried out the Medium filter – it actually provided a really interesting beginning background for this image. When set to Multiply blend mode, it gave a really rich feel to the background and made lots of the lines fade into the background. (The other filters used in this image were Corel Painter’s Particle Shop using the Heat Trail filter which gave the pretty string effect and Photoshop’s Spherize filter which really rounded up my butterfly – I will blog on this one soon as it is actually a lot of fun to use also.)

How does this filter work? Heads Up – technical info here – skip if you do not care

The filter is controlled by adjusting the size of the Radius slider which goes from 0 to 600. The following info is from Adobe Photoshop Special Effects Focus Guide from 2003. Amazing this filter is still around and useful. If you set a Radius of 25, the Median filter will select the image using groups of 25 pixels. It blends these pixels together according to the closeness of their color and brightness – any pixels that are too different from the average color in a group of pixels will be discarded.

Adobe says the Median Filter “reduces noise in an image by blending the brightness of pixels within a selection. The filter searches the radius of a pixel selection for pixels of similar brightness, discarding pixels that differ too much from adjacent pixels, and replaces the center pixel with the median brightness value of the searched pixels. This filter is useful for eliminating or reducing the effect of motion on an image.” Yawn!

When would you use this filter?

The filter can be used as an alternative to the Gaussian Blur filter to blur parts of an image to change the depth of field. The result can be more natural-looking similar to a real photograph effect.

At a very low level (like 1 or 2), it has a smoothing effect which can help reduce moire patterns and noise in an image. With scanned images, try setting it to a minimum amount to fill in small white scanning speckles. See my Scanning with a Black Box Blog for more on this.

The filter averages out colors that are too different from those found in the set Radius value. Here is an example of a Radius set very low at 19 and it gives a nice soft depth of field with just the guitar strings sharpened by removing the effect with a layer mask using a brush set to black. This image is one of my favorite images for practicing new techniques from ISO Republic called Guitar Man.

Image of Guitar Play with Median Filter applied

At higher levels, it produces soft, abstract images that still contain fairly distinct edges in contrast areas. This could be used for some very interesting effects.

The Median filters seems to work really well to just soften up any distracting things in the background but does a better job than the Gaussian Blur filter. I will try using this more and decide if it really is better. I tried to soften a waterfall with this filter and use a layer mask so only the water was affected. PS says it works well with motion blur, but I actually found the Motion Blur filter works better for this. (See my Smoothing Those Waterfalls Blog on how to do this.) It would probably be an easy experiment so give it a try. I plan on being a little more sporadic with my blogging for awhile but I will continue blogging. Just not on a very regular schedule. In the meantime, continue working in Photoshop and trying out all the cool things it has…..Digital Lady Syd


HOW TO SUBTLY ADJUST AREAS OF AN IMAGE USING TWO METHODS

Image of a Spanish Cay runway marker in the Bahamas
During Photoshop Week 2019 on Creative Live, I watched a segment by Randy Van Duinen called Lightroom and Photoshop for Architectural Photographers. I did not think there would be much relevant to me, but it is loaded down with some new ways of looking at photographing and post processing. It is an inexpensive class and frequently on sale – definitely worth the buy. One of Randy’s tips is about de-emphasizing those distracting areas and putting them into shadows (or as in the above, making the foreground lighter). After working with his technique, I figured out a way to get the same results using the Properties Panel on a Layer Mask, so check out the Alternate Workflow for these steps. Not sure which is the easiest to do.

WORKFLOW WITH GAUSSIAN BLUR FILTER

  1.  Select an areas with the Lasso Tool (or whatever selection tool you wish to use).
  2. Set the Quick Mask options (by double clicking on the 2nd from the bottom icon on the Tool Bar) to show the Masked Area as you want the selected area or area to be changed not covered by the overlay and the Opacity to 100% . Then enter Quick Mask mode.
  3. Go to Filter -> Blur -> Gaussian Blur and set the Radius to a large amount to make a nice smooth transition between selection and other areas. Should be able to see the transition clearly. Click Enter to close filter.
  4. Press Q or press the icon again to exit Quick Mask.
  5. With selection active, open a Curves Adjustment Layer. Can now light or darken the layer mask or change the color of the layer. Remember that the Red, Green and Blue Color Channels can also be used to adjust the results.

Screenshot of the RAW file for Spanish Cay in the Bahamas
The above shows what the original image looked like as it brought in from Lightroom (just used Basic Panel corrections, cropping/straightening, and Lens Correction Panel). Duplicated the Background layer (always do this) and applied Topaz (for website link see sidebar at my Tidbits Blog) Sharpen AI (use this a lot now) set to Focus and Remove Blur 0.65 and Suppress Noise 0.20 – note that a layer mask was added as it definitely was too much sharpening for the soft clouds. I had decided that I wanted the small bush on the left to be brighter and the foreground to look more sandy than it did in the image. On another duplicated layer, the Lasso Tool was used to first select the bush. The the Quick Selection mode was used to select the areas that I DID NOT was to change. See the Screenshots below to see how the edges blend once opened in Quick Selection mode and the Gaussian Blur filter chosen and set to a Radius 52.4 pixels. By changing the radius size, the blending can be set they way you want. If you want to see some of the background, set the Opacity for Quick Mode lower than 100%. The Lasso Tool is really not that exact so if more accuracy is needed, just use the Paint Brush Tool to adjust the mask.
Screenshot of Gaussian Blur on bush
The image below shows how the blending looks with a larger area selected and a larger Radius size is used. Definitely have a much smoother transition. This time the Radius was set to 182.0 pixels, but Randy uses much larger sizes on his images. It definitely depends on the size of what you are blending and how large an image you have.
Screenshot of the foreground in Gaussian Blur for Spanish Cay image
Once the filter is applied, just click Q or the Quick Selection icon to exit and a selection will be available to apply to any type of Adjustment Layer, but with this workflow it usually involves the Curves Adjustment Layer. Of course a Levels Adjustment Layer could be used or some of the color Adjustment Layers could be used like Hue/Saturation. For the above two different Curves Adjustment Layers were used, one for each area selected. The last step was to add a Levels Adjustment Layer vignette (see my How to Create a Subtle Vignette blog).

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Thought I would show you a couple images that also used this same technique. In the leaves image, by darkening the background, it actually created a very 3D effect. This time the large leaves in the foreground were selected with the Lasso Tool since I wanted to darken the background. Inside the Quick Selection Mode a Gaussian Blur Radius of 424.3 pixels was used to create a more subtle transition. Then back in Photoshop a Curves Adjustment Layer was used to darken the area somewhat. The vignette was from Topaz Lens Effects’ preset Soft Olive Green and keeping the opacity low at 32.83.

Image of some pink and green Coleus Plants at the Magic Kingdom
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My last example uses the Watercolor1 Mockup by Digital Florist. Just popped my Day Lily image with a butterfly and put on the drawing pad. The original mockup was very light, so by selecting the sketch pad, the background was darkened using this technique (Gaussian Blur Radius set to 355.2). This now draws the focus to the image and not all the painting supplies. (The crazy background was created using  Corel Particle Shop filter’s Expression and Spring Silk Ribbon brushes.)

Image of a Mockup showing my Day Lilies and a butterfly

ALTERNATE WORKFLOW

There is another way to do this same technique without using the Quick Mask Mode and I will list the steps below. I like both ways of doing this, so give each one a try.

  1.  Add a black layer mask to your image.
  2. With a larger soft brush, switch to white and paint over the area you want changed. For the top image it would be the left bush or foreground area. Note, you have do this twice for the different areas if you want to use different setting in the Adjustment Layer for each.
  3. Add a Curves Adjustment Layer above the image and clip it to the layer (press the first icon at the bottom of the Curves Adjustment Layer Panel or CTRL+click between the Image and Adjustment Layer layers in Layers Panel. Otherwise the selection changes will apply to the whole image. Do your adjustments. Levels Adjustment Layer can be used here – sometimes it gives a little better result.
  4. Click on the Layer Mask of the image layer to bring up the Properties Panel – set the Feather to get the soft transition you want. To see it as if you were in the Quick Mask Mode, click the (\) key to see the overlay or ALT+click to see just the black and white mask. Also fine tune your Layer Mask with a brush at this point in case areas were missed.

Alternate Workflow Screenshot

Not sure which way is easier, but it gives similar results. I do believe the Gaussian Blur is a little easier to see the effect, but with the overlay in the Alternate Method, it is still pretty easy to see.

This technique can be used for just a subtle change which is what I like, especially in landscape images. Have a good one until next time!…..Digital Lady Syd

Digital Lady Syd’s Related Blogs:

How to Use a Selection to Draw Focus in an Image
Using Curves Adjustment Layers to Get Rid of Shadows and Highlights


A NEW LOOK AT CHROMATIC ABERRATION

Image of the Carousel at Jacksonville ZooThought I would share a tip that can really improve your photos, especially landscapes. Wikipedia says “Chromatic aberration manifests itself as “fringes” of color along boundaries that separate dark and bright parts of the image.” This seems to be very apparent in blue skies in landscapes with lots of trees. The above image was taken at the Jacksonville Zoo of a vintage-looking carousel (see my Only in Florida! Tidbits Blog for a closer look). Just a few Basic panel adjustments Lens Corrections (checking just the Enable Profile Corrections and Remove Chromatic Aberration boxes) were done in Lightroom before opening up Photoshop.

This technique was passed along by one of my favorite Photoshop people, Blake Rudis (who says he learned it from Steve Perry), at his f64 Academy in a video called The Color Blend Mode – there is a free downloadable action here to do this technique. The image had some empty branches against the blue sky along with was some real blue-cyan chromatic aberration. In Lightroom the Remove Chromatic Aberration checkbox did not remove this and to be honest, I did not  notice it until I was in Photoshop since only the upper corners were affected. Below it can be seen what a subtle difference the technique makes – you can definitely see the cyan color shift due to the Chromatic Aberration in the sky. It is hard to see, but the branches on the right side image look a bit darker and sharper, especially where the larger branches are present. This was also true on the upper left side of the image.

Image showing with and without Chromatic Aberration

So here are my steps to get rid of this ugly blue edging in this case but it will work on any color of chromatic aberration.

  1. Duplicate the Background layer (CTRL+J) and turn it into a Smart Object by right clicking on the layer text area and selecting Convert to Smart Object. A stamped layer (CTRL+ALT+SHIFT+E) could be used and duplicated if in the middle of post-processing.
  2. Go to Filter -> Blur -> Gaussian Blur and set the Radius somewhere between 6 and 20. I used 6.8 for this image.
  3. Change the layer blend mode to Color – now the whole image is blurred.
  4. Click in the Smart Filter layer mask and CTRL+I to turn it black. With a regular soft round brush, paint with white just in the areas you want the blur to correct the chromatic aberration.

Blake does not use a Smart Object, just applies the filter and adds a black layer mask – then paints back areas that need correction. This technique also works if the chromatic aberration is not completely removed when using the Camera Raw filter. What is really useful is that this is a localized correction and only affects the part of the image that needs the correction. The Blur does not affect the whole image! I find this gives a very subtle and sharp result to the bad areas. Here is a link to one of my Tidbits Blogs called  Defringe that Nasty Blue Edge from Trees On a Bright Blue Sky! done a while ago where 4 other ways to remove Chromatic Aberration are presented if you would like to try out some other techniques.

There were lots of steps used for final processing in this image – Topaz (see sidebar at my Tidbits Blog for website link) Glow, Topaz DeNoise, Photo Filter Adjustment Layer, Vignette, and clean up layers. Overall I was pretty happy with the final results.

Give this Chromatic Aberration trick a go, especially if you have cyan blue going around those branches in trees. It works really great! Also check out Blake’s f64 Academy website as he has lots of great ideas on improving pictures. Well, back to my organizing until next week…..Digital Lady Syd