As photographers, we can always benefit from sharpening our images, especially when shooting in RAW. Whether it’s to correct image softness, emphasize elements or prepare for final output, your images are likely to gain from Photoshop’s sharpening tools. The tools you decide to use will depend on your sharpening needs and your photography workflow.
In this article I will be discussing the top five sharpening tools in Photoshop: Camera Raw Detail Panel, Unsharp Mask Filter, Smart Sharpen, High Pass Filter, and Blending Modes.
What is Sharpening?
Sharpening tools in Photoshop enhance the perceived detail in an image by altering contrast at the pixel level. That is, the sharpness tools make the contrast between each pixel more or less pronounced. If you find this confusing, you can learn more about this topic in this article.
Sharpening tools enhance image detail by amplifying the contrast between pixels, making lighter pixels lighter and darker pixels darker. Photoshop uses an algorithm to detect pixels with the most tonal differences within an image and makes them more or less pronounced. These tonal differences are called “edges.”
Let’s look at the example image below. In this photo, the edges are highlighted by the red line along the pixels. This is where the most tonal differences occur.
Note that Photoshop cannot identify differences in tonal ranges that are a result of noise. For this reason, sharpening often increases image noise visibility.
How to Find the Sharpening Tools
You can find all the sharpening tools under the filter tab in Photoshop. When you click the filter tab, a drop-down menu will show the available filter options. The image below shows the locations of the sharpening sliders found on the filter dropdown menu.
Camera Raw Detail Panel
The Camera Raw sharpening sliders are some of the most potent sharpening tools in Photoshop. You can find the sliders in Camera Raw Detail Panel. The Detail Panel has four sliders that you can use to sharpen your image: amount, radius, detail, and masking.
Camera RAW will apply a default amount of sharpening to all images opened in Camera RAW. The default values are as follows:
Amount – 40
Radius – 1.0
Detail – 25
Masking – 0
Note that this default setting is not applied in JPEG and TIFF images because Photoshop assumes that JPEG and TIFF images are already sharpened.
Tips Before We Begin:
- Use Photoshop’s grayscale preview while adjusting your sliders. Using this preview will make it easier to identify the changes the sliders make to your images. To do this, press either Option key (MAC) or Alt key (PC) while moving the sharpening sliders.
- Use Photoshop’s split-screen feature for a before and after preview. This is accessed by pressing the “Y” icon at the bottom right corner of your screen in Camera Raw. Doing this will make it easier to view the changes you are making to your images.
The amount slider determines the intensity of sharpening applied in a photo. Increasing its value will apply more contrast between pixels enhancing the appearance of detail within the image.
The other three sliders in the Detail Panel (radius, detail, masking) are dependent on the amount slider. That is, if you have a zero value for the amount slider, the other sliders will not work.
The amount slider has a maximum value of 150. Note that any amount over 100 will increase the noise in your image. Also, it can make pixel edges visible and decrease the aesthetic appeal of the picture.
Let’s look at some examples below.
The image on the left has a default value of 40, while the image on the right has a value of 140. The difference between the images is noticeable. The image on the right has more contrast and appears to have more texture.
The Radius slider determines the number of pixels that will be affected by sharpening. The number of sharpened pixels on the edges increases as you increase the radius slider. For instance, with a radius of 1, one bright pixel and one dark pixel will be adjusted on each edge. A radius of 3 changes three bright pixels and three dark pixels on each edge.
Within a photo, edges can take two forms: fine or soft. Fine edges have significant tonal transitions while softer edges will have less tonal changes. A small radius setting will emphasize fine edges within a photo but not the soft edges, while a wide radius will emphasize both fine and soft edges.
Let’s look at some examples.
On the left image, we used a radius of 0.5 pixels. This radius value only sharpens fine edges and not soft edges. To demonstrate, I boxed an area consisting of primarily soft edges. Notice that the edges in this area are not highlighted which means sharpening was not applied.
On the right image, we increased the radius slider to 3 pixels. Notice that this sharpened nearly all the edges in the photo including the boxed region. At high radius value, more pixels are sharpened, including softer edges.
Tip: A radius less than or equal to 1 pixel works excellent at targeting fine edges if your images do not have plenty of soft edges. To sharpen softer edges using a radius of 2 pixels will work great.
The detail slider controls the amount of contrast applied at the edges.
It has a range of values from 0 to 100 with a default value of 25. Values below 25 will suppress the amount of contrast while values above 25 will enhance it.
The detail slider also controls the amount of sharpening in high vs. low-frequency areas. Frequency is the area(s) of a photo that has soft edges. At low-values, the detail slider will only emphasize fine edges or low-frequency areas in your photo. This setting is often used to reduce blurriness in images.
Increasing the detail slider will emphasize contrast in the softer edges or higher-frequency regions of your image. A high value is often used to give images more texture.
The detail slider is excellent because it allows you to enhance the sharpness of an image without increasing noise.
Note: If you have a low-frequency photo, using detail slider values above 50 will have little impact. Also, values above 50 tend to exaggerate very fine details such as image noise.
Let’s look at the images below to see how the slider impacts an image.
The grey scale image on the left has the default value of 25 for the detail slider. In this case, only areas with low frequency are highlighted and being sharpened.
The image on the left has a detail slider of 95. Notice that the number of edges highlighted has increased. At this setting, both low and high-frequency areas are being sharpened, creating an improved appearance in texture.
The masking slider constricts the areas sharpened in your image. Low values will sharpen most of your image while high values will sharpen only edges with the highest contrast.
This slider is helpful if you want to avoid sharpening in certain areas of your photo. As the masking slider increase, the areas sharpened will decrease.
The greyscale preview for the masking slider is black and white. The mask only sharpens the white areas in the preview.
Let’s look at the example images below. The left image has the masking value set to zero. The greyscale preview is primarily white, which means most of the image is being sharpened.
On the right image, I’ve set the masking value to 100. In this case, the mask is sharpening only the areas that are high in contrast, highlighted in white.
Unsharp Mask Filter
The Unsharp Mask filter is the most widely used sharpening tool in photoshop and rightfully so. The Unsharp Mask filter offers the control, power, and speed that other sharpening filters do not provide.
This filter applies the following default settings:
100 – amount
1 – radius
0 – threshold.
It is important to note that these sliders are sticky and will not revert to the default values when using the filter on a new image.
Similar to Camera Raw, the default settings are not applied to JPEGs or TIFF images.
Why is it called unsharp mask when it’s used to sharpen?
The unsharp mask derives its name from a process used to sharpen analog photos. The analog process uses an out-of-focus or “unsharp” negative of the original photo to sharpen the edges.
Photoshop applies a similar process to digital photos. It takes a blurred version of the image and places it in the background. It uses the differences between the blurred and the original image to identify the edges needed in the sharpening process.
The word “unsharp” refers to the image used for sharpening and not to describe the image after sharpening.
1. Amount and Radius Sliders
The Amount and Radius sliders used in Unsharp Mask work the same as the ones in Camera Raw. The only difference is the Unsharp Mask’s Amount slider has a broader range of values than in Camera Raw. The maximum value for the amount slider in the Unsharp Mask filter is 500%, while the max value in the Camera Raw filter is 150%.
- For the Amount slider, avoid using values higher than 100%. They will typically increase noise and give your images an unrealistic feel.
- For the Radius slider, avoid using high values, this will cause sharpening to appear as a contrast adjustment rather than a sharpening adjustment.
The threshold determines what the Unmask filter will consider an edge when applying sharpness. Low threshold values, define edges as pixels with small differences in tones between them. High threshold values, on the other hand, view edges as pixels with a significant difference in tones between them.
The Threshold slider is similar to the masking slider found in Camera Raw. These two sliders are both designed to constrict sharpening. They differ, however in how they restrict sharpening. The threshold slider restricts sharpening by changing the tonal difference required for pixels to be treated as an edge. On the other hand, the masking slider does not affect how we classify edges. The masking slider restricts sharpening based on the tonal differences between pixels.
While the difference in methodology between the sliders is subtle, it is important. It determines how the sliders in Camera Raw or Unsharp Mask affect an image when high values for the threshold or masking slider are used.
For example, when using a high value for the masking slider in Camera Raw we can sharpen soft edges by using a high detail slider. When using a high value for the threshold slider soft edges cannot be sharpened.
Limitations of Unsharp Mask
While the Unsharp Mask is powerful and versatile there are some limitations I would like to mention.
- The threshold slider does not work very well, low values enhance noise while large values give the image an unnatural appearance.
- Increasing threshold slider eliminates sharpening in the mid-tones. Midtones are usually the areas in the image that require the most sharpening.
- The Unsharp mask doesn’t provide sharpening in the best locations. It often over-sharpens highlights and under-sharpens mid-tones and shadows.
The Smart Sharpen filter is very flexible, offering more sliders than any sharpening tool available on photoshop. It offers advanced settings that give it additional control not available in the other sharpening tools. These advanced settings include noise reduction, blur removal, fade amount, tonal width, and radius.
1. Amount and Radius
The amount and radius sliders in Smart Sharpen Filter work the same as the sliders in Camera Raw and Unsharp mask.
2. Noise Reduction
Most sharpening tools do not offer a noise reduction slider. This feature is useful since increasing sharpening also increases image noise.
3. Remove Slider
The Remove slider controls the application of the Amount slider. It offers three different control options: Gaussian, Lens, and Motion. Within the remove slider, there is an “accurate” checkbox. Selecting this box will result in a softer sharpening.
→ Gaussian Blur: The Gaussian is the default setting in smart sharpen. It detects edges and sharpens them evenly.
The Gaussian blur performs identically to the Unsharp Mask filter in a specific setting: when the radius and amount sliders are equal and the threshold value set to zero.
Selecting the accurate checkbox while using the Gaussian Blur will soften the sharpening applied to the image.
→ Lens blur: This option uses a different algorithm when sharpening an image. The Lens Blur attempts to differentiate edges from noise.
In doing so, it will sharpen edges precisely to reduce sharpening halos. This will apply more sharpening to the mid-tones in the image than when using Gaussian blur.
→ Motion blur: Motion blur is best used to reduce blur caused by movement in an image. It offers a direction-setting that allows you to set the angle of movement to sharpen.
4. Advanced Sliders
The smart sharpen filter allows you to apply the following sliders separately to the shadows and highlights in an image.
5. Fade Amount
The fade amount slider gives you additional control over the sharpening occurring over the highlights and shadows.
A value of 0% will apply the same level of sharpening to a specific tonal range. On the other hand, an amount of 100% will remove any sharpening occurring at that tonal range.
For example, Let’s say you only want to sharpen your highlights and not your shadows. To do this, you would set the fade amount for highlight to 100% and set the fade amount for shadows to 0%. This removes the sharpening effects applied in your highlights while leaving the sharpening effects in your midtones and shadows constant.
6. Tonal Width
The tonal width slider determines the range of tones that will fall into highlights or shadows. For instance, increasing the total width will treat more tones as highlights while decreasing it will reduce the tones treated as highlights.
This tool is useful in changing the number of pixels affected by advanced sliders. That is if you increase the total width for highlights the other sliders will control more pixels.
The radius slider will function similar to the radius slider used above but will only apply to a specific tonal range.
High Pass Filter
This slider is unique in that it is designed to enhance high-frequency elements in a photo while simultaneously overlooking low-frequency areas. This means that edges in a picture will be enhanced while other areas will be left untouched.
Unlike other sharpening tools, the highpass filter comes with only one slider- the radius slider.
The radius slider on the high pass filter functions the same as the other radius sliders.
The highpass filter displays your image on a greyscale. The filter sharpens the white areas while leaving the grey areas unsharpened.
Let’s look at the images below.
As you can see, at a pixel value of 2.8 only the fine details are highlighted. Increasing the pixel value to 138 include nearly every pixel in the image and highlights almost the entire picture.
2. Blending Modes
Using blending modes is one way you can adjust the intensity of the sharpening applied by the high pass filter. Although, blending modes offer less control than an amount slider they are easier to apply.
The blending mode options used for sharpening are Overlay, Soft Light, and Hard Light. Each of these will emphasize different tonal regions when sharpening an image.
The soft light mode produces the least sharpening in your image. The hard light mode will provide the most sharpening and overlay will provide a medium level of sharpening.
Enhancing / Reducing the Intensity
There are two other ways to adjust the sharpening intensity using the highpass filter:
- Use multiple filters. The more filters you use, the sharper your image will become.
- Use the opacity slider. By adjusting the opacity slider, you can reduce the effect of the filter you applied.
Adjustment Brush- Camera Raw
The adjustment brush in Camera Raw applies localized sharpening to your images. You can do so by adjusting the sharpness slider (see image above) and brushing over the locations in the image you want to sharpen.
The sharpness slider on the adjustment brush has a range of negative to positive 100. Negative values will reduce the sharpness in an image. An amount of -100 will completely blur the picture. Positive values will increase the sharpness of your photo. A high positive value will increase both sharpness and noise in an image.
When using the adjustment brush, you can also adjust the type and size of the brush to accommodate the portions of your image you are trying to sharpen. To sharpen the entire image, max out the size slider and brush over the whole image. To sharpen fine details reduce the size of the brush and brush over the features where you want sharpening.
Other Sharpening Filters
There are several other sharpening filters that I didn’t discuss in this article because they are relatively easy to use and offer no control.
These filters include Sharpen, Sharpen Edges, and Sharpen More. The Sharpen, Sharpen Edges and Sharpen More filters apply a universal amount of sharpening to the entire image with no adjustment sliders available.
Similar to the highpass filter, to adjust the intensity of the sharpening when using these filters you can add multiple filters or use the opacity slider.