Easy, Realistic Lens Blur / Bokeh in Sagelight


Duck at Punalu’u Pond (Big Island, Hawaii)

Now that I am working on the next update, I am going to spend some time writing about how to use Sagelight.

(note: I see I wrote quite a long blog post, which really can be used a general article for using Sagelight.  Read the Conclusion for a good summary)

Sagelight has a lot of wonderful and powerful functions, and the Lens Blur / Bokeh is definitely one of those higher end functions in Sagelight that can be used for amazing effects.

Lens Blur and Your Images

Depth-of-Field is all the rage right now, emphasized with the new cell phone cameras, such as my Galaxy S5 and it’s Boke mode (which works with limited success, but it very nice when it gets it right). 

And as well DOF/Lens Blur should be all the rage, because Depth of Field is a great option, even when your camera didn’t deliver it in the original image.

Sagelight has a powerful, fast Lens Blur / Bokeh function that can help your image in many ways.

As Ansel Adams showed, half of Creative Photography takes place after the shot is taken (someone should create an editor with a name that takes off on that notion…hmmm…), and either creating or adding lens blur to an image can be a very powerful part of the post-production process.

I say “creating or adding” lens blur, because sometimes you want to add Depth of Field where there is none, but also a camera will give you a slight or good depth of field, but you might want to add more to focus on your foreground object.

Natural-Looking Lens Blur / Bokeh

In this article, I am writing more about creating natural lens blur and bokeh effects.  That is, creating a lens blur that, well, looks like a real lens blur, as if it came from the camera.  Much of the time, Bokeh is used for artistic effect, which can be very nice, but doesn’t always look like it was the natural result directly from the camera.

If you’re looking for more realism and natural results, the Bokeh and Lens Blur function in Sagelight is very useful.  In fact, I wrote this blog because I was using it for some of my images, and the Lens Blur/Bokeh in Sagelight absolutely saved a number of pictures that weren’t nearly as worthwhile in their original state.

Keys to Natural and Realistic Lens Blur / Bokeh

I will describe these more in the follow paragraphs, but a quick overview of the keys to realistic post-production lens blur:

  1. Don’t blur too much.  This can often be an issue, much the same as the issue with saturation – with saturation, we tend to get acclimatized to the color as we add it, and it’s easy to go too far; what looks great at the time has far too much color when we see it later.

    In the same way, sometimes it seems nice to have all this power to create a lens blur, but going too far looks less natural.

  2. Creating a Selection Mask.  With most images, there is a foreground and a background.  Somewhere in most images (where a lens blur is useful anyway, since the idea of a lens blur is to bring out an object in the foreground), the foreground element(s) overlap onto the background we wish to blur.

    The human eye is amazingly perceptive, and any mistakes where the foreground gets blurred, or the background doesn’t in these overlapping areas can ruin the effect.

    By contrast, it also works the other way around! A great mask on even a small object, keeping the foreground sharp and the background blurry (even just a little) can really sell the effect – our eyes pick up on it, and it makes it look real, adding realistic depth.

Lens Blur vs. Bokeh

For natural results, there is basically no difference between Bokeh and a Lens Blur.   Lens Blur is basically that – a blur through the digital equivalent of an aperture of a specific shape (which you can choose). 

Bokeh is just all the rest added – the highlights and effects that tend to be more for an artistic presentation vs. realism. In a nutshell, Bokeh is simply a superset of the Lens Blur. Lens blur + effects = Bokeh.

If I use the term Lens Blur or Bokeh, it’s all the same function in Sagelight – the Bokeh function.  I tend to use the term “Lens Blur” here, because the term tends to reflect the idea of realism vs. effect. The Lens Blur / Bokeh function is called “Bokeh” in Sagelight because it has all of those things needed for a lens blur plus all of the Bokeh additions. If you’re familiar with Adobe Photoshop, the Lens Blur function is similar to the Bokeh function in Sagelight – Sagelight does more, but the Bokeh in Sagelight and Lens Blur in Photoshop do basically the same thing.  Sagelight adds effects such as the Backlight and more “traditional” bokeh functions, but the lens blur functionality is essentially the equivalent between Photoshop and Sagelight.

Lens Blur / Bokeh vs. Fast Depth of Field Function

A quick note about the Fast Depth of Field function.  This function is, as it says in the name, a very fast version of a “variable blur”, which is very similar to a Lens Blur, except that it is more of a digital / Gaussian-type blur and not a Lens Blur (i.e. through a shaped aperture, such as a circle, hexagon, etc.).  The Fast Depth of Field function is very nice, also, and has some great uses. 

I will write more about this when I get to the example with the duck (shown above).


Sunbathing Sea Turtle at Punalu’u (Black Sand Beach), Big Island, Hawaii

A Simple, But Effective Lens Blur / Bokeh

Looking at the picture above, I can see I overdid the Lens Blur a little bit in the foreground.  But, that doesn’t really matter.  It looks great, and this is one of those cases where you see the flaw in it mostly because you’re familiar with the original, and not because it stands out as a glaring issue.

Even though the foreground is a littler overdone, the Lens Blur in the background worked out perfectly, so I just left it as it was. Since I saved the mask, I can just do it again later.

This is a good case of a picture that looked ok on its own, but using the Bokeh controls in Sagelight made it much better.

It may look like I just used the Lens Blur / Bokeh controls without masking, but this isn’t the case.  Two main points of this blog post are about using simple masking (i.e. nothing complicated) and the Backlight Slider control in the Sagelight Bokeh controls.  Read more about this below.


Some Information About the Images in this Blog Post

There’s a couple things going on with the images in this blog post.

  • All Images use a mask to achieve the effect.  I will discuss this in a section below, but its important to note that all images here have a small mask applied to them to help the Lens Blur effect.  Selection masks are used in the foreground area to make sure it doesn’t get blurred.

    You can use the Lens Blur / Bokeh without creating a selection mask, and this also creates a great effect.  For this article, small masks were used to separate the foreground and background, creating a more realistic lens blur (vs. a bokeh effect).

    Selection masks are the main reason the Lens Blur / Bokeh works and looks natural.

    In most cases, the masks used were simple.  With some of the more advanced masks, it is amazing how easy they were to generate.  More about this later.

  • Backlight Slider.  The Baclight Slider was very useful with most of the images in this article.  The Backlight Slider in the Bokeh controls really makes a difference, and made all of the difference in many images, particularly the turtle image, as well as the duck image, and the flowers.

    Try using the Backlight Slider in the Bokeh.  It can really help an image along.   It works because it only lowers the light on the blurred area to the degree it is blurred, darkening less in softer areas, and darkening more in more blurry areas – this turns out to be a great effect that also can look very natural, highlighting your subject.

  • All Images are Natural HDR, as well.  I’ve been working with ‘Natural HDR’, i.e. the idea of bringing out the dynamic range of an image in a way that looks natural.  It’s just been my thing lately.  All images in thise post are “HDR” images in some way or another.  Most are meant to look very natural (for example, you wouldn’t believe how awful the duck picture was originally, as well as some of the others), and the flowers are pushed a little bit into the artistic HDR level just for the effect.


Quick and Easy Masking / Selections

One of the elements that makes the Lens Blur / Bokeh work well – and look natural – is masking/selections.

In the Bokeh Controls, you can select the “More” tab and open up the masking controls.  Here, you can draw or load an existing mask.

The Lens Blur / Bokeh will then avoid these areas by blurring around them.  This creates a nice, tight edge that looks like a natural Lens Blur.

Quick and Basic Masking

The good news here is that you usually don’t have to worry about making an exact mask around your subject.  Many times, you can just create a quick mask and go with it.  The masking controls are interactive, so you can adjust your mask quickly as you go to get rid of problem areas.

In the mask above, for example, you can see that I just went through and quickly made a very sloppy mask.  The Sagelight Bokeh function will show you the results as you go, so I was able to just adjust areas I didn’t like.

Here is the result:


You can see little blurred edges where I didn’t mask with complete accuracy.  But, it looks ok for me, and this is another one of those cases where you don’t really see it unless you already know its there.  In a way, I kind of even like these blurred edges because they look a little intentional.

If I was really annoyed by these blurred edges (which I am not in this case, but with other pictures, I might be), there are two things I can do, both of which are pretty effective:

  1. Redo the Bokeh.  I can just press the Undo Button and re-enter the Bokeh function. I can also save the mask, so if I see this later on, I can redo it.   When pressing the Undo Button and re-entering the Bokeh function, it will return the same settings and mask from the previous Bokeh application, and will make the image look the same as before you pressed the Undo Image – except now you can change things.

    Now, you can edit the mask and get rid of those little edges.

  2. Use the Clone Brush (A good general option, too!).  You can also use the clone brush to clone some of the areas around the blur – this effectively removes the blur, and a little practice with the clone brush goes a long way; you can adjust these edges in just a few seconds, creating a more edgy, natural look. 

    This is a good option when you notice this sort of thing well after you’ve used the Bokeh (or any function where something went unnoticed).   Then you don’t have to worry about any other things you’ve done with the image, such as color and contrast adjustments.

Accurate Masking and Lens Blur / Bokeh


If I want to spend a little more time, I can create a more accurate mask, which will create even better results, removing those little blurred edges.

In this case, the masking didn’t take very long – I was able to use a combination of the Sagelight Masking and the Fill Brush to create this mask in less than 5 minutes (the subject of another blog post)!

A good example of more accurate masking is the duck or the turtle – these masks were either a little more accurate or didn’t have many complicated edges (which don’t require great accuracy in the mask).


In the case of the duck, because of the less defined edges around the body, I made a more accurate mask, and then interactively edited the mask in the Bokeh Controls for some quick feedback on where the mask needed a little more refinement.

The Backlight Slider Made a Big Difference

Note the use of the Backlight Slider used in the Bokeh – it created a nice vignette effect, highlighting the main image.

In many ways, the Backlight Slider saved this image.  It was too bright overall, and generally lowering the brightness didn’t work out too well, as it made the picture too dark.

Using the Backlight Slider created a vignette for the image only in the blurry areas – the  Backlight Slider was used only in those areas where I wanted to defocus the attention, creating even more of a focus on the subject (the duck in the water).

See the next image below, for comparison between the non-Bokeh version and the one above.

Lens Effect: Lens Blur vs. Fast Depth of Field Blur



As you can see, the difference between the Lens Blur / Bokeh version and the pre-bokeh version really makes the difference in the presentation of the picture.

Also note the use of the Backlight Slider.  Many things in image editing work best when they are imperceptible – they draw your attention to your intended object of focus without gaining any attention themselves.  Such is the case with the use of the Backlight Slider in this image.  It successfully put a vignette in the blurry areas but is essentially not a noticeable part of the image.


Circle Shapes

In addition to the use of the Backlight Slider in the Bokeh, there is also one more thing to notice: the circular highlights in the background.

In the image above, you can see the circle shapes.  These are created by a true lens blur – not a Gaussian, Box, or other blur.  The Fast Depth of Focus, for example, tends to be more Gaussian-like, which would just blur the entire background, but not create circles.

This is how a blur looks like with a short depth of field on a camera, which is why it’s called a Lens Blur, and also why it looks just like it was taken by a camera.

In some cases, you may want more of a general blur, but for the effect of using a lens, the Lens Blur can emulate many different aperture shapes – circle (in this case), hexagon, octagon, and so-forth.  There are also more “” shapes, such as a square, triangle, and so-forth, used mostly for effect (but not realism).


“An Old Car Near Top Hat, near Foyil, Oklahoma” by Kevin (Flickr)

One More Example (Randomly Downloaded From Flickr)

Here is another example, one that I downloaded from Flickr. I made no changes to it except to perform the lens blur.

This is a good example, for a couple reasons:

  1. The Building in the background makes the picture look a little busy.  If we want to put focus on the car, we can blur the background with the Lens Blur
  2. But… the Building in the background adds value to the image.  On the other hand, the building really helps build the picture.  This may be a case where using a Lens Blur isn’t the best thing to do.  I am going to do it anyway to demonstrate the Lens Blur, but its good to point out they elements in the image often give a sense of symmetry or contrast to a picture.  Adding a Lens Blur will basically make this into a different picture.  It’s really up to whatever your artistic view of it is, and what you want to stand out in the picture.


Using a Light Lens Blur – Keeping it Realistic (and also the sense of Time and Place)

In the above image, I used just a light touch on the Lens Blur.  This can keep the sense of realism high (i.e. not look like an intentional, after-effect Lens Blur).

With this particular image, it also helps keep the sense of time and place.  The building has a slight blur to it, but its still obvious it’s a building, keeping the symmetry and mood of the image – an older wooden building next to a rusting, classic car.

This image came out very nice, and looks real – which is the point.  This particular picture is a good reminder that sometimes doing less is more (which really should be a mantra in image editing!)


Masking the Hood Ornament is What Really Sells the Lens Blur

The effect of the lens blur, in terms of keeping it realistic, is really about the little things.  In this case, it was the nice masking on the hood ornament. 

I drew this mask (over the entire car, including the hood ornament) in about 5 minutes.  It’s not really complicated, especially when you can go back and forth between the Bokeh and Editing the Mask so easily.



In the above image, you can see more of a close-up of the hood ornament, and how such a little thing – because it has such nice foreground properties – really helps sell the idea of the lens blur as a natural blur.

Heavy Lens Blur – both a Caution and an Option

As mentioned in the last section, a lighter lens blur can help keep it natural.  But, there are times when you want it to be heavier.  In this case, the masking usually needs to be more accurate.

Be careful not to blur too much, or you enter tilt-shift territory:



A heavy Lens Blur, such as the one above, can be nice, too – the focus is more on the car, even though it does get more of a tilt-shift look (i.e. it looks a little miniaturized).  It may not look completely natural, but it still looks nice and can really help the car stand out (especially if you then use the HDR, Power Details, Retinex, or a host of other tools to bring out the details – again, not realistic, but nice anyway).


While researching and implementing the new UI changes for Sagelight, I decided to write about various things, as well as post some images. 

While I was doing that, I used the Lens Blur function so much – as it helped really save some images – I thought I’d write about my thoughts. 

Sagelight’s Lens Blur / Bokeh function is very powerful and also extremely quick in the scheme of Lens Blur functions (Lens Blur functions are very CPU-intensive), and can provide some great effects for your image.

In this article, the effect I’m looking at is the realistic lens blur.  You can use the Bokeh Function for many things, such as tilt-shift (i.e. miniaturized look), smoothing background elements, Bokeh effects, as well as a realistic lens blur.

Using the Selection Masking and Backlight Slider can create a powerful, natural-looking result that focuses the eyes on the object in the foreground.  With a light blur (as demonstrated with the ‘Old Car’ image above), you can also keep the sense of the background and context of the image while focusing on the foreground.

Creating a Selection Mask is very easy, and in most cases you can just do a general mask inside the bokeh function in just a minute or two.  With some images, you might want to be more accurate with your masking, but this doesn’t usually take much more time.  One of the reasons for this is because you only really need to mask the area where the foreground meets the background, and you typically don’t need to create an accurate mask for the entire foreground object.

One of the reasons I thought about writing this article is because I realized that creating a realistic lens blur – including foreground objects – isn’t that hard, nor is it time-consuming.  Using a couple simple rules (such as creating a quick selection mask, blurring less than more, not to mention using the Backlight Slider) in addition to just a little practice with the Bokeh controls, can make an incredible difference in your image.


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