I assume that one of the most important thing is for every photographer, to set up an impressive image gallery with high-quality photos. Low-quality pictures might look noisy, blurred, dark or bright, while good quality photos are drawing the viewer’s attention. For high standard pictures first and foremost we have to get the correct exposure, then we have to make sure our images look sharp and crisp by focusing accurately. However, if our images are slightly out of focus, thanks to digital technology, there is a possibility to improve them in post-processing. Sharpening is one of the most basic editing tools for fixing soft images, and all photographers should know how to use it.

What is image sharpness?

All photographer knows what sharpness means, however sometimes we disagree about how sharp that image is, as everybody detects sharpness differently. Sharpness means the picture’s entire clarity, in relation to focus and contrast as well, and most noticeable next to image edges, where the contrast differences look quite large. Moreover, the sharpness of the picture depends on the resolution and acutance. In addition, images need high acutance and resolution to be detected particularly sharp.

Resolution is the amount of detail in a picture, and mainly influenced by the photographer’s camera technique – bear in mind, that camera shake affects sharpness-. Furthermore, the resolution is limited by the DSLR camera sensor.

Acutance is the edge contrast of an image and depends on the quality of the lens and the method of post-processing as well.

Sharpness mainly depends on the photographer’s camera technique, so it’s good to know, that the tiniest camera shake can dramatically reduce the sharpness of our picture. Moreover, the viewing distance also affects the sharpness of the photo.

Lenses are more important than the camera, when it comes to image quality. Maybe it’s hard to believe, but entry-level cameras with good quality lenses can deliver excellent sharpness throughout images, as they have less optical distortion and chromatic aberration.

What is image sharpening?

Nowadays in the world of digital technology, every picture needs some sharpening in image-processing to improve quality, because digital camera sensors and lenses are not accurate, and blur the images to some degree. Sharpening process means that we increase the contrast between the pixels in the image, to achieve crisper, more detailed appearance. As we discussed earlier, cameras can automatically apply some sharpening to JPEG images, but for RAW files.

Images with small mistakes, – such as minor camera shake or slightly out-of-focus – can be also repaired by sharpening. Even more, when we take images in low-light situations or at a far distance, many details can disappear. Although, we can bring those details back with image editing software like Photoshop, Lightroom.

Why we need to sharpen our images?

The main reason of the sharpening, to bring out fine detail by darkening the darker pixels and lightening the brighter ones.

Before the sharpening process we need to be aware of what the image is going to be used for, web or print. If we would like to use it for the web, first we need to resize the picture for the website’s preferred size. However, after that step our image can look blurry and a lot less sharp than the full-sized photo. Then we can apply sharpening to the image, but the question is how?

How to apply sharpening on images?

There are several ways in Photoshop to find the optimal sharpness level for our image. Let’s see three sharpening technique that generate the best results.

First I am going to explain how Unsharp Mask works.

  • Open up the desired image in Photoshop, then create a duplicate layer.
  • Then go to the Filter menu and choose Convert for Smart Filters, so it won’t affect the original image, it stays safe.
  • In the Filter menu choose Sharpen filter and select Unsharp Mask.
  • Now we can see 3 sliders in the dialogue box: amount, radius and threshold. We can increase the amount by moving the slider to the right side, and to decrease it drag the slider to the left. Amount is responsible for the strength of the sharpness in the image. Radius manages the width of sharpness at image edges on the photo. Threshold controls the entire sharpness of the image.
  • If we select the Preview option, we can see the image with the applied settings.
  • Try to apply different amounts, to see which one works best for the chosen image, then adjust settings accordingly.

Keep in mind, that too little sharpening results soft image, while too much sharpening causes jagged lines, and it’s essential to find the balance between them. One of the best advantage of Unsharp Mask is, that it gives more control when sharpening images, as it has options, while other filters are automatic, so we have no control over them. Moreover, it doesn’t increase noise.

The other method is using Smart Sharpen filter on our images by going to Filter, Sharpen, then select Smart Sharpen from the list.

This is very similar to Unsharp Mask filter, but it has a noise reduction option which is useful to remove unwanted noise, without affecting the edges. Moreover, we can find a remove option, which sets the sharpening algorithm to sharpen the image.

  • Gaussian blur is the method what Unsharp Mask uses.
  • Lens blur is to find edges and detail in the image, plus reduces halos.
  • Motion blur reduces camera blur effects or subject movement. We can also set the angle of the motion at this option.
  • By using the shadows, highlights sliders, we can remove dark and light halos.

The last method is the High Pass filter. It is a very simple sharpening filter with only one option, to change the radius, by setting it to the minimum level. It makes the image grey.

To see the sharpness of the picture, choose overlay, soft light, hard light or linear light option.

If we don’t want to apply sharpening to the whole image, we can use selective sharpening by using a mask or a selection tool, to avoid sharpening in specific areas of the image. For this method we need to select Duplicate Layer first, then apply one of the selection tools to isolate the desired part of the image and sharpen it apart.

So, these are only a few of the options of the sharpening techniques and every photographer has an own preferred method which can vary from image to image. Make sure, sharpening is the last step in post-processing, then apply it in small amounts, and repeat the process if needed. High amounts of sharpening  may destroy the picture and results unnatural and ugly look.

This is it! I hope I have covered everything about image sharpening. Try out more techniques and use the one that works best for you!