CHAPTER 6 — Sharpness (Clarity) Correction

Lack of clarity or sharpness in your photos results from a camera limitation and is interpreted by the photo viewer as a “lack of depth” and fuzzyness. A common complaint of digital photographs is that they lack sharpness. In actual fact digital photos do lack sharpness because of how the sensors of a digital camera are arranged. Traditional methods used to sharpen your photos, including the widely adopted ‘unsharp masking’, are going to simultaneously shift and distort the colors of your photos. Perfectly Clear’s proprietary method brings clarity to your images while maintaining Real Color and, it does it without the artifacts and shortcomings traditional sharpening methods would introduce.

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One reason for a lack of Sharpness is camera manufacturers intentionally blur your photo

Digital photographs often lack sharpness. There’s several reasons for this, one of which is intentional. Are you aware that manufacturers intentionally blur the light being captured by your camera?

There’s a good reason that camera’s blur the very signal they’re capturing

In the Article 15 Ways Your Cameras Distorts Color the subject of aliasing is covered in some detail. Suffice to say here that aliased data is data that can cause unpredictable outcomes when your photo is being created or “enhanced”. Camera manufacturers are very cognizant of these severe problems and for this reason they want to minimize aliasing. Aliasing of color data is exacerbated by the Bayer array arrangement of sensors in your camera. To reduce the aliasing of the energy, there’s an anti-aliasing filter placed in front of your camera’s sensors. This anti-aliasing filter is designed so that incoming energy which would have struck a single sensor is, instead, spread out over several sensors. This gives the interpolation algorithm additional color information to work with for determining the color of a specific pixel but, it does so at the cost of reducing sharpness.

Just what is Clarity?

It’s important for our discussions to define what “clarity” or “sharpness” is. In layman’s terms think of it as the clarity of the “edge” between two objects. You’d think that where one object ends and another begins would be pretty simple … at least in theory. But the theory and the reality can differ widely in digital photography where the world is not defined by lines but rather by “dots” or “pixels”.

Because of how digital camera’s capture information there’s other reasons digital photos lack sharpness

Pixels aren’t lines, they’re dots, so where does one object end and the other begin? In a world of dots, edges can be hard to “distinguish” because:

• The vast majority of cameras arrange their sensors in a Bayer array. Each sensor represents a single pixel and gathers light for only one color – either red, green or blue. To create the final photo, each single colored pixel will be compared mathematically with the pixels surrounding it, and a final mixture of three colors for the pixel will be interpolated from the color information of these surrounding pixels. Interpolation is a fancy word for “averaged”. In effect, the single color of a single pixel is averaged with the different colors of surrounding pixels to get an ‘averaged’ color. This “averaging” leads to “flatness” – rendering edges between objects less distinct. For a good explanation of the de-mosaicking process see this camera limitation discussion and see www.ronbigelow.com
• some edges of photographed objects will be in the middle of a pixel, and pixels are indivisible
• if your photo is converted to a JPEG image each pixel will be grouped into a square with 7 other pixels. These 8 pixel JPEG squares are created without reference to “edges” and each 8 pixel square can then have different compression applied. The different compression can create edges where there weren’t any, and destroy or distort edges that were present. This camera limitation is covered here.

There can also be a lack of clarity or sharpness due to camera lens distortion but that’s beyond the scope of the discussion here.

We live in a Three Dimensional world so sharpness is important

The indistinct edges in your photo leaves a flat appearance. The sharper the distinction between edges of objects in your photos the more easily the human brain attributes “depth” and “dimensionality” to the image. As humans we live in a three dimensional world and therefore the more depth and dimensionality there is in our photos, the better those photos will act as memory triggers and help us recall the original images of the event in the mind’s eye. So, like contrast, our minds use sharpness to recreate depth and dimensionality in our photographs.

The challenge with traditional Sharpening methodologies is they distort color and introduce artifacts

There’s several challenges when your camera or you, using traditional photo “enhancement” software, sharpen your images. Firstly, sharpening a photo is traditionally achieved by varying the saturation between adjoining pixels. Most “enhancement” software does this using a variant of an unsharp masking process.

This process requires you, as the user, to define three variables. Once you’ve selected the constraints for the variables they’ll be applied throughout the entire image. Because these variables lack granularity and intelligent adaptability, no matter what constraints you choose they’ll prove to be arbitrary and result in color shifts and distortions in your photo. Secondly, the more you sharpen your images the more likely you’ll create artifacts or “ringing” (sometimes called halos).

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The artifacts and “ringing” seen in the above images can arise for several technical reasons, including: amplification of “aliased” color information, the de-mosaicking algorithm unsuccessfully resolving the edge, the revealing of JPEG squares, the JPEG squares interfering with the sharpening algorithm, or from photon effects.

Conventional thinking is that you may wish to sharpen your image two or three times for the desired outcome. Using traditional methods, each of these sharpening actions is going to increase color distortion and risk the introduction of artifacts.

Sharpening photos the traditional ways takes a lot of time

The unsharp masking methodology was spawned in the dark room of film developers. Sharpening varies the local contrast along the edges in your photos. With an Unsharp Masking tool the sharpening process requires that you set three variables for the tool.
• an Amount which signifies to the tool the amount of saturation change you wish to make between pixels (amplitude of change desired),
• a Radius which signifies to the tool how many pixels away from the “edge” you wish included in the sharpening process, and
• a Threshold which tells the tool what tonal difference between pixels (0-255) is to trigger sharpening.
These are all dependent variables meaning that changing any one variable impacts the operations and outcomes of the other two. This means that achieving the most appealing sharpening now becomes an iterative process, requiring you to adjust and readjust all these variables until the earlier of getting a satisfactory result and fatigue of the process itself. While you’re doing this just remember that you’re continually shifting saturation in an arbitrary way and distorting the colors of your photo the entire time.

Perfectly Clear clarifies photos while maintaining Real Color and never introduces artifacts

With all these challenges in mind Perfectly Clear developed a proprietary methodology that sharpens images optimally and will NOT create ringing, will NOT reveal JPEG squares, and will always maintain the Real Colors.

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This is made possible because Perfectly Clear’s sharpening correction stands on the shoulders of its patented Perfect Exposure process which increasing and decreasing light by providing the essential and correct missing eye function your camera lacks.

In essence, the technology adjusts adjoining pixels using the principles of how the eye gathers more or less light. By effectively increasing the light on some pixels and reducing it on others that adjoin, but doing it just as the human eye would do it, a sharp edge appears. This innovative approach is also bounded by the patented approach to maintaining the Real Color with the RGB Triplet Ratio. The technology avoids all information represented by the smallest signals.

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Perfectly Clear also constrains its sharpening correction with the physics principles of light to avoid sharpening any incidents of small signal because this data is:
• apt to be characterized by photon effects,
• have the least precision, and
• be most prone to come from a low signal to noise sensor response.
If one were to sharpen data with any of these characteristics it’s most likely going to result in amplifying noise, create artifacts and distort edges. When Perfectly Clear provides a tweaking control to improve its auto correction, as in Perfectly Clear Pro Software, the slider is always an independent single (ie. – easy to use) control.

Maintaining the accurate colors of your photo while providing crisp sharpening is necessary for a high quality photo

Increasing sharpness is imperative for a realistic representation of what you saw when you took the photograph. As we’ve seen there’s several causes for a lack of sharpness including how the original signal of your photo is interpolated. This is a camera limitation. However it’s also introduced by traditional “enhancements” such as brightness and contrast. Increasing sharpness by traditional methods takes considerable time and causes significant color distortion. The Sharpness Correction in Perfectly Clear is constrained by the patented invention of Perfect Exposure, which limits light adjustments to the physics principles of how the eye gathers light ensuring that the correction reproduces photos with true, accurate color … Real Color.

Perfectly Clear overcomes your camera’s limitation of inadequate sharpness in your photos, a very common problem of digital cameras. Unlike other photo “enhancements”, the Perfectly Clear correction operates to add sharpness in a manner consistent with how the human eye gathers light. This includes replacing the essential missing eye function the camera lacks.

The results are Accurate Photos that match the original image in the mind’s eye and serve to preserve Precious Memories perfectly. Accurate Photos are Superior Photos and science shows superior photos have the greatest emotional impact with viewers.