Tag: Sharpness

Photoshop Sharpness – Getting the most out of your camera

Today I want to address a problem that most of us face at some point during our lives (that sounds dramatic, but it is true, at least if you care about photography anyway!): how to get a perfectly sharp image.

There are a couple of great articles on the Sleeklens blog covering sharpening and noise reduction (two things that are deeply intertwined) in Lightroom, so for this entry I will focus on how to get the sharpest image right from your camera so that the post-processing is as simple as possible. And, for those situations where we had to deal with some blurriness anyway, I will briefly explain a nice technique for that in Photoshop as well.

Capturing the image

First of all, let’s define sharpness, for the purpose of this article, as the contrary to blurriness. This helps us focus on what we need to do to get a sharp image, which is the same as getting an image as free of blurriness as possible.

But where does blurriness come from? In photography, this can originate as an effect of moving the camera or a subject in motion while taking a photo (motion blur), or by more specific aspects related to the camera itself, the lens or filters being used (Gaussian blur). Then there is also the artificial blur that can be introduced with so-called low pass filters, but we are not concerned with that right now.


So let’s start with the easy one: motion blur. Unless you are trying to capture moving objects with long exposure photography or experimenting with your camera in different ways, motion blur is something you want to avoid. And there is only one way to do it: get a sturdy tripod and use it whenever you can. Many people only get their tripods out of their bags when they want to take photos under low light conditions, but I really recommend always using your tripod, unless you are after an action shot that happens too quick to set the tripod or if you don’t carry one at all.

That said, even with a very good tripod, a mild wind can shake your camera in a way you cannot perceive but still make your final image look blurry, so if there is any wind at all, try to put your body between the wind and your camera to block as much as you can. Sometimes this might prove harder than it seems, but most of the time this is as much as you can do.


Finally, use the delay function of your camera to give some time for the tripod to stabilize after pressing the shutter button. Two seconds are usually enough, but the exact time will depend on the camera you use.

Now let’s move on to the hard part. Sometimes you might notice that even on a perfectly still day and after spending $500 on a tripod, after you take your photo, go back home and open your file on Photoshop or Lightroom, you realize that the image is blurry anyway! But before throwing away your tripod or getting a new camera, read on (even though it is true that better cameras produce sharper images, chances are that you have some things that you are able to improve in your workflow before thinking about that!).


One easy thing to try if you are taking long exposures is to turn off the image stabilization of your lens. That sounds counter-intuitive, but if you are using a tripod and taking relatively long exposures, the image stabilization system can actually try to compensate for some motion that is not there, finally producing a slightly blurred image. Image stabilization has helped to push the exposure time at which we definitely need a tripod a lot, but when using a tripod, it becomes unnecessary so taking it out of the way might be helpful sometimes.

The next one is related to the focal length you use. Building lenses is a delicate and difficult task. And building lenses that retain the same sharpness throughout the whole focal length range is almost impossible. It is for this reason that lenses have something called ‘sweet spot’. Simply put, when you take the aperture to the extremes (very small or very large f-numbers) your lens will produced less sharp images. Each lens is different, so the only way to find out the ideal range for your lens is to go out and take the same image only changing the f-number, but as a rule of thumb, staying three steps away from the limits should work quite well.


Finally, using certain types of filters will also affect the overall sharpness of your image. Probably the filters that have the worst effect are neutral density (ND) filters. These filters, used to capture long exposure images in daylight, can have very strong effects both in the sharpness of your image and in the white balance.

But what happens if you end up with a blurry image anyway? You might have needed to use an ND filter or you just did not realize your image was blurry until you got home. What can you do?

Frequency separation in Photoshop

Photoshop, as well as Lightroom, has a set of filters devoted to the sharpening of your images. They are simple to use but they also have a downside: when you want to remove the blurriness of an image, what the filters do is enhance the borders by applying a so-called high pass filter. The problem with high pass filters is that they tend to introduce noise, and this noise can sometimes damage parts of your image, especially those with low contrast such as the sky.

Take a look at this image, captured in the Cordillera Blanca in Peru:

DSCN1995_withouthsharp DSCN1995_withsharp

The top image is the original file without any added effect while for the bottom one a simple sharpening filter was added (Filter -> Sharpen -> Smart Sharpen… in Photoshop). They both might look pretty similar, but if you look closely enough, the top one is a bit blurry, especially noticeable in the mountains. This has been improved in the bottom one, but the problem I mentioned before is there: the sky looks now rather noisy. This is easier to see if we zoom in to 100%:



You can improve the situation by creating a layer mask in Photoshop and masking out the sharpening effect on the sky, but then it gets quite complicated when you try to select the horizon. Luckily enough, there is a nice technique called ‘frequency separation’ that comes to our rescue.

The term frequency separation comes from the fact that images, same as for instance music, are formed of many different components that have different frequencies. While in music high frequency refers to high pitch tones and low frequency to low pitch tones, in photography high frequency refers to regions where there are many changes in contrast within a small area while low frequency refers to regions with few changes over that same area. For instance, in our image, the sky is a low-frequency area (because for a given area there are not many changes in color) while the mountains are high-frequency areas.

So what we want to do is separate the low-frequency part of our image from the high-frequency part in order to be able to separately edit them. This way, we can increase the sharpness in the high-frequency part (mountains in this case) without affecting the low-frequency part (sky).

The first thing we do is duplicate our base layer twice. You can name these new layers however you want. I called them here ‘Low Frequency’ and ‘High Frequency’.


The next thing to do is separate the frequencies. The low-frequency component is achieved by blurring the image until you see a uniform sky (or any other part of your image that you don’t want to get modified when applying the sharpening filter later on). The amount of blur will vary, but it usually is relatively large (around 10 pixels or more), so that the whole image looks blurry. For this you make the top layer (high frequency) invisible, select the middle layer (low frequency), go to Filter -> Blur -> Gaussian Blur… and apply the amount you feel happy with. In my case, I chose 50 pixels.


For the high-frequency component, we make the top layer visible again, go to Image -> Apply Image… and select Subtract as the Blending method and apply it to the Low-Frequency layer (see the different parameters in the next figure).


After you do this last step, the image will look like the one above. This is because you are looking at the difference between the two layers. To get a normal image again, just change ‘Normal’ to ‘Linear Light’ in the drop-down menu right above your layers and to the left of opacity.


We are now ready to apply the sharpening filter. For this, we select the top layer, go to Filter -> Sharpen -> Unsharp Mask… and we select the values according to what makes our image look the way we want.


Notice that we are able to select relatively large values for the Amount and the Radius and, as we will see in the next couple of images, the sky is unaffected by this.



The top image shows a 100% view of a part of the image before the sharpening and the bottom image shows the same area after the sharpening. Notice that the sharpening is visible in the mountains but not in the sky, thus avoiding the appearance of unwanted noise. The really neat thing about frequency separation is that we don’t need to worry about a very precise horizon selection, but with just a few steps, everything is automatically done.

I know this might sound a bit complicated at first (it was for me, at least!) but with practice you will work it out. So, as usual, have fun with it!

A Guide to Using the Adjustment Brush in Lightroom

Correcting exposure, color balance, and contrast are likely how you begin editing the majority of images in Lightroom presets. Often, it might be all that is required to finish editing the image; however, to take your images a step further Lightroom has given its users a tool called the Adjustment Brush. It allows for photographers and retouchers to localize their editing by carefully selecting specific parts of the image to enhance, hide or correct. The Adjustment Brush is a fairly easy tool to master, but it comes with a few settings that need to be understood, to use this tool well. This is the complete guide to using the Adjustment Brush in Lightroom.

The Adjustment Brush tool is found in the Develop module of the Lightroom panel which can be found if you have an installed Lightroom presets.  You can quickly access the Develop module by using the keyboard shortcut ‘D’. The Adjustment Brush tool is marked as a dotted circle with a brush coming out of it – make a habit of using keyboard shortcut ‘K’ to access the tool, to save time when retouching.

Adjustment Bursh

Once the tool is selected, you will see that the mouse pointer turns into a circle. It marks the area affected by the Adjustment Brush. Further, you will notice that it opens a number of options that change what affect the Adjustment Brush will have on the image.

The first two sliders control the temperature and color tint of the image. These, in short, control the white balance settings of the Adjustment Brush. For example, you could use this tool stylistically to add a complimentary color in the shadows of an image for a more saturated photo.

Adjustment Bursh2

Moving forward, the next six sliders control the exposure and tone settings of the Adjustment Brush. Exposure will change the overall tone shift of the area affected by the Adjustment Brush. The contrast will control the ratio between the black and the white values of the image, which can be the further adjusted by the last two ‘Whites’ and ‘Blacks’ sliders. The Highlights slider will control the extent to which the Adjustment Brush affects the brightest sections of the adjusted area, while the Shadows slider will control the darker areas. Adjusting these settings can help you bring certain parts of the image forward or hide other areas in shadows.

Adjustment Bursh3

The next section allows for changes in clarity (one of the features you have to consider for rating system in Lightroom), which controls the contrast of the lines in the image, and saturation, that affects the intensity of the colors in the area of the adjustment brush. Often clarity can be great in revealing the amount of detail present in the image; however, usually you want to avoid adding it to faces as it will accentuate lines and creases in the skin – to avoid that we can use the Adjustment Brush tool to only increase clarity outside those areas.

Adjustment Bursh4

The next section is responsible for correcting the issues caused by the camera sensors. First, are the Sharpness and Noise sliders that can be used to make parts of the image stand out from the rest or used to reduce noise and grain caused by the camera sensor. The Moire slider is there to compensate for the Moire effect that occurs when a frequency of pattern in the image aligns with the pixels of the sensor, resulting in a distortion of that pattern. The Defringe slider reduces the chromatic aberration caused by lens shortcomings.

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Further, the Color option of the Adjustment Brush allows you to select a color cast that the brush will add to the affected area of the image. Last part of the Adjustment Brush options controls the Size, Feather, Flow and Density of the Adjustment Brush. A quick way to adjust the size of the brush while retouching is to use the keyboard shortcut ‘[‘ to make it smaller and ‘]’ to increase its size. The Feather of the Adjustment Brush controls how quickly the Adjustment Brush will fade into the rest of the image. The larger the Feather level – the more gradual the fade will be.

Adjustment Bursh6

Flow affects how quickly the Adjustment Brush is applied to the image. If it is set to 100%, it means the Adjustment Brush will affect the area to a maximum level. If it is set to 50%, only half of the effect of the Brush will be seen.

The Density slider is similar to Flow and controls the amount of change that can be applied by the Adjustment Brush; however, unlike Flow, it will limit the effect indefinitely, meaning that once it is set to a specific value that area will always remain affected at that percentage, unless the Adjustment Brush settings are changed.

Last, the Auto Mask options attempts to guess, which parts of the image you aim to be affected by

the Adjustment Brush. It does so by checking for contrast ratios between pixels, meaning that if you have a subject in the image that clearly stands out from the background, it should be able to easily identify that you only want the subject affected; however, if the background is very cluttered, likely, it will not be able to distinguish the subject well.

Adjustment Bursh7

If you are finished with the first set of adjustments, you can create a new brush. Simply click the ‘New’ option in the Adjustment Brush settings panel, set the new settings for the Adjustment Brush and start applying it to the image. Note, that you will be painting on top of the first Adjustment Brush that you used. A quick way to undo the changes made by the Adjustment Brush is to hold the ‘Alt’ key while brushing the areas you want to be undone.