Sharpening and noise reduction
DOI link for Sharpening and noise reduction
Sharpening and noise reduction book
When to sharpen All digital images will require sharpening at one or more stages in the digital capture and image editing process. Even with the best camera sensors and lenses, it is inevitable that some image sharpness will get lost along the way from capture through to print. At the capture end, image sharpness can be lost due to the quality of the optics and the image resolving ability of the camera sensor, which in turn can also be affected by the anti-aliasing filter that covers the sensor (and blurs the camera focused image very slightly). With scanned images you have a similar problem, where the resolving power of the scanner sensor and the scanner lens optics can lead to scans slightly lacking in sharpness. These main factors can all lead to capture images that are less sharp than they should be. When it comes to making a print, this too results in a loss of sharpness, which is why it is always necessary to add some extra sharpening before you send the photograph to the printer. Also, between the capture and print stages you may find that some photographs can do with a little localized sharpening to make certain areas of the picture appear that extra bit sharper. This briefly summarizes what we call a multi-pass sharpening workflow: capture sharpening followed by an optional creative sharpen, followed by a final sharpening for print.