Sharpen Filter in Image Processing
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Sharpen filter in image processing improves spatial resolution by enhancing object boundaries but at the cost of image noise:
        i) Highlight fine detail.
        ii) Enhance detail that has been blurred.

There are various methods of sharpen filtering depending on applications:
        i) High pass filtering.
        ii) High boost filtering.
        iii) Derivative filtering.

This filter is used mainly to increase the brightness at edges and boundaries. Its kernel size can be 3 x 3, 5 x 5 or 7 x 7 as shown in Figure 1371a.

Kernel size: (a) 3 x 3, (b) 5 x 5, and (c) 7 x 7
Kernel size: (a) 3 x 3, (b) 5 x 5, and (c) 7 x 7
Kernel size: (a) 3 x 3, (b) 5 x 5, and (c) 7 x 7
(a)
(b)
(c)

Figure 1371a. Kernel size: (a) 3 x 3, (b) 5 x 5, and (c) 7 x 7.

In Gatan Digital Micrograph, sharpen filtering function is performed with kernel size 3 x 3 (Figure 1371a (a)) by the following steps:
        i) Open or select the image you want to sharpen.
        ii) Choose SHARPEN from the SPATIAL FILTER submenu under the PROCESS menu.
        iii) A new, sharpen-filtered image will be created.

In Photoshop, sharpen filtering function can also be performed (e.g. Figure 1371b) by the following steps:
        i) Open or select the image you want to sharpen.
        ii) Choose SHARPEN from the SHARPEN submenu under the FILTER menu.
        iii) The image is then sharpened.

Image processing with sharpen filtering in Photoshop
Image processing with sharpen filtering in Photoshop
(a)
(b)
Figure 1371b. Image processing with sharpen filtering in Photoshop: (a) Before sharpening and (b) After sharpening.

 

 

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