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4. Other blurring kernels
Since itās clear that subtraction and blurring are the core of this kind of sharpening, I started wondering what if other kernels are used instead of, or at the same time with, GB.
Letās take Surface Blur (SB), aka Bilateral Filter, a well known edge preserving blurring algorithm. If it keeps edges and wipes the rest out it should lead us to think: SB equal something to enhance everything but the edges. Letās see:
(Fig 4.1) Subtraction using the edge-aware SB instead of GB.
(Fig 4.2) Affecting less the edges, the texture is more enhanced.
(Fig 4.3) The result using SB Radius = 6 and Threshold = 15.
It works as itās supposed to do. Besides the fact that SB isnāt the fastest ļ¬lter ever in the Photoshop arsenal, there are more annoying things. Itās required a bit of experience to ļ¬nd the correct radius/threshold couple; due to the algorithm itself, at large radii a reversion starts to appear and instead of more blurring we get more edges coming back:
(Fig 4.4) SB with Threashold 15 and radii 6.0 - 50.0 - 100.0; SB fails at larger radii and detail appears again.
A much better edge preserving ļ¬lter is the Weighted Least Squares (WLS) operator. Unless you are an experienced programmer or you ļ¬nd the way to put your hands on a computer with MatLab and Photoshop both installed, to use it is quite a problem.The results are remarkable indeed, check the links at the bottom of the page.
A simple yet powerful Photoshop tool to effectively boost the local contrast of an image, by means of a smart algorithm which avoids the clipping issues typical of methods like shadows/highlights. The user interface is simple and clean, with just one slider, allowing the user to customize the effect in a straightforward way.
In 2000 Imacon, now Hasselblad, created a new proprietary format for the Imacon scanners, the Flexible File Format or fff. 3F has determined the biggest revolution in the field of original analog scanning since the introduction of the drum scanner.
First of all forgive us the word play, which might come off as presumptuous. However, we felt like we came up with something that perfectly summarizes our philosophy in this arena by uniting the concepts of high resolution and quality reproduction.