Sharpening Digital Photographs

Sharpness is the level of delineation of fine detail in a photograph. In a sharp image fine details can be seen. In an unsharp image those details tend to look blurred or smudged.

Have you ever wondered why some digital photographs appear to be sharper that some others? There can be three reasons for an image to be less sharp than another image. Camera movement at the moment of exposure will motion blur. Incorrect focus will create out of focus images. Both of those deficiencies deteriorate the sharpness of a photograph. Neither of those deficiencies can be corrected after the photograph is taken. The third reason arises from the design of digital camera sensors. The unsharp appearance caused by the digital sensor design can be remedied in post capture processing.

Digital camera sensors consist of millions of light sensitive receptors that send a signal to a processor, which the creates a digital image from the data received from the sensors. Each of those sensors sits in its own site on the sensor and each site is separated from adjacent sites by a micro thin wall. Those wall capture no image detail. The in-camera image processor compensates for the lack of data in those spots, but that becomes tricky when those points are areas of an image where there are tonal or color changes. Since the data on those edges is created not recorded, it does not have the distinct delineation that areas created by the light sensors.  Fortunately, the techies found a way to improve on the cameras deficiencies when a digital photographs is processes after initial capture in camera or by scanner. That’s right. This applies to scanned photographs too.

Most good digital photo processing software will have provisions to “sharpen” a digital image. That control is usually called Sharpening, although in some software it is called Unsharp Mask. I’ll spare you the tedium of learning how the term unsharp mask came about. All you need to know is that it is a sharpening tool.

I am a Mac user so I am not familiar with image processing software for Windows computers except for Adobe’s Photoshop CS, Photoshop Elements, and Lightroom. The Windows and Mac versions of those program are alike.I use Apple’s  Aperture to process my images, but I have used Apple’s iPhoto too.  Both programs have sharpening tools, but Apertures is more sophisticated. However, iPhoto’s tool is quite sufficient for most amateur photographers.   

In the gallery are variations of several photos that go from no sharpening applied to maximum sharpening applied. You will have to look at them carefully since the image size is relatively small, and in smaller images the effect of sharpening is harder to see. However, if you looked at the same image full screen the differences in sharpness would jump out at you.

If you want your photographs to look as best they can, then you wan to sharpen them.