Image Sharpening

The sharpness of the image recorded on your camera is affected by many factors: focus, lens, aperture, shutter speed, raw or jpeg format.

The process of sharpening is done through software tools by increasing the contrast along edges of pixels and enhancing them to heighten image definition. Applying sharpening to your images is both a technical and creative process. It can help emphasize texture and detail and it is essential when resizing for the final output. The difficulty always lies in knowing how much to apply.

Sharpening should be thought of as a multi stage approach within your workflow. There are three stages where a file can be sharpened: Raw Capture, Post-Processing and Output.

Please note that it is very important to judge the sharpness of an image by zooming in 1:1 (100%).


Raw Capture Sharpening

A loss of sharpness is to be expected during the in-camera demosaicing process and therefore it is important to compensate it by applying an appropriate amount of sharpening during the raw conversion stage. When applying sharpening here, it is important to consider the image content, exposure and noise level of the image. If this action is applied without paying enough attention to the details, sharpening artifacts can be created that may become problematic further into your workflow.

Post-Processing Sharpening
This stage of the process involves sharpening the image after it has been converted from Raw format to the Tiff format in RGB colour mode. At this point, you can sharpen the image using Photoshop’s built-in filters like SmartSharpen, Unsharp Mask and High Pass. You can also deploy more sophisticated 3rd party Photoshop actions like Photokit Sharpener or sharpening plugins like NIK Sharpener Pro and FocalBlade. How much sharpening to apply depends on your creative aesthetic and intention for the image. When sharpening the image it is important to take the content into consideration and to keep within its limitations. You want to emphasize the edges without compromising the texture, as in skin tone and without introducing fake texture into the flat areas, as in backgrounds and skies. It’s always important to keep in mind that the file may be resized or that further sharpness may be applied in the final output, therefore it is essential to keep the sharpening to a reasonable amount.

Output Sharpening
Sharpening in the output stage is highly customized and fully dependent on the actual print size. As a rule, the larger the print size, the more sharpening is required to be effective.


Raw Conversion with Adobe Camera Raw

Below are two before and after examples of sharpening being applied in the Raw conversion stage in Adobe Camera Raw. (Examples are based on Nikon D700 12MP Raw original.)

Adobe Camera Raw

Adobe Camera Raw - Full image: no sharpening

Adobe Camera Raw - Details: no sharpening

Adobe Camera Raw - Details: no sharpening

Adobe Camera Raw - Details: appropriate sharpening applied

Adobe Camera Raw - Details: appropriate sharpening applied

As you can see in the above example, sharpening at the Raw conversion stage does not need to be too aggressive to get the desired effect.


Post-Processing in Adobe Photoshop

Below are two examples of good sharpening versus excessive sharpening using Unsharp Mask filter in Photoshop at 100% views. (Examples are based on Nikon D700 12MP Raw original.)

Photoshop Unsharp Masking: appropriate sharpening

Photoshop Unsharp Masking: appropriate sharpening

Photoshop Unsharp Masking: excessive sharpening

Photoshop Unsharp Masking: excessive sharpening

The second example above clearly suffers from over-sharpening. The edges in the details have halos all over and the final look is too artificial. The Radius setting in the Unsharp Mask is a bit too heavy thus resulting in undesirable heavy dark keylines in this image.

Badlands, South Dakota, USA

Badlands National Park, South Dakota, USA

In summary, when sharpening any image file it is important to take the content of the image into consideration and to keep within its limitations. You want to emphasize the pixel edges to bring out sharpness and clarity without compromising the texture or introducing pixel artifacts. It is important to remember there are normally three stages of sharpening: Raw Capture, Post-Processing and Output. The converted raw files may be resized and further sharpening may be applied in the final output. Therefore it is crucial to keep the sharpening to an appropriate amount prior to the final output stage.


MacBook Air for travel photographers

A workshop participant recently asked me about whether the MacBook Air is a good choice for travel photographers. I responded with a few main points that I would consider if I found myself one day inside the Apple Store with a credit card in hand.

MacBook Air

The MacBook Air is a great choice for travel photographers. The obvious selling point is its weight – 2.3 lbs (~1 Kg). However, with this small form factor design, you’ll have to give up a few things that have been with the MacBook family for a number of years. Here’s a short list:

1. Hard Drive: Instead of traditional hard drives found on other MacBooks, the Air has completely switched to flash storage. The advantage of using SSD flash memory is speed. As there are no moving parts, it’s also more shock resistant and in theory less prone to mechanical problems. Macworld has posted some initial speed ‘torture’ test and found that there is no performance degradation over time. This is excellent news. The disadvantage of using SSD flash memory, however, is the price per gigabyte. Right now Apple is only offering maximum 128 GB of storage with the 11-inch model. If you require more storage, it will have to be through external drives.

2. Ports: The Air lacks any Firewire ports but it does have one USB 2 port on either side. In addition, the 11-in model does not have the SD card slot which is available on the 13-in model. I’m a fan of Firewire 800 as I have 2 portable drives for travel so it will be an issue for user like me. If you are planning on using external USB 2 drives then this will not be problematic. Please note that in order to connect the Air to ethernet, an adapter is required.

3. Graphics: According to the Macworld benchmark tests, the graphics card (NVIDIA GeForce 320M – 256 MB) does provide speedy graphics. However, I have not tested it against the MacBook Pros with graphics intensive photo apps like Lightroom or Aperture so I reserve my comment until I have the chance to do so.

Louis Au

As an avid photographer and educator of digital photography, Louis Au knows first hand how challenging it can be to navigate through the labyrinth of ever-changing capture technologies while maintaining quality and sanity.
Louis consults and provides educational seminars for professional photographers around the world. He implements workflows, provides technical training and advises future direction regarding digital capture technologies for individual photographers and studios with small or large work groups. Louis is also one of PIKTO’s instructors for their year-round photography workshops in Toronto’s Distillery District.


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