droger的資訊心得整理

前二天有朋友貼了一個將會出現在Photoshop CS5的新功能，可以將許多物件或不規則形狀做自動拉伸及補償，其實這項功能在CS4也有，稱為Content-aware Scaling。

2007年，Shai Avidan和Ariel Shamir在電腦圖形運算相當有名的SIGGRAPH會議當中發表，後來首先在Gimp繪圖軟體中實現這項技術，推出了一個稱為Liquid Rescale的Plugin，後來Adobe就雇用了其中一位發表人，在CS4當中推出了Content-aware Scaling。

而這項濾鏡的原理主要是運用到碎形的基礎，不過在這邊先跳過複雜的數學公式，只看對於碎形的文字介紹，從維基或這裡的一份簡介可以了解到：

【「碎形幾何學」（fractal）是一門新數學，它能夠處理不規則、無定形且複雜的圖形，諸如樹木的分枝、海岸線、動物的犄角、河流分叉、山勢、螺貝圖、雲的形狀、樹葉、閃電等形狀，用我們所學的歐幾里得幾何學，無法說明這些特殊的形狀，但是這些外觀上極不規則的自然界複雜型態，都能夠以碎形幾何學來予以解釋。

碎形具有自相似性，「自相似性」是指某圖形的任意部分經放大或縮小後，仍然可以展現出原來的型態，也就是指整體圖形和部分圖形都具有相似型態。所以將碎形圖形無限放大，將會出現與原來圖形極相似的形像。自然界有多種形態都擁有碎形性，裁切密林或山水風景相片的某部分，將其貼在另一張風景相片上，則往往不會損傷我們對此張相片的印象，這就是具相似性的形態和圖形所擁有的特點。】

知道碎形的性質之後，就可以開始解釋這個濾鏡的演算運用了。

首先像這樣的一張風景圖，在人眼看起來是有許多不重複性的。

但是把它經過高反差的處理之後，就可以發現到其實當中有許多碎形分布的相似性存在。

而這個濾鏡的所運用之處就在於，它會去自動計算出這類型照片當中的碎形分布，所以在伸縮拉放的過程當中，就會做出自動補償的動作，於是人眼看起來就不容易察覺到破綻，而在CS4當中，大多是運用在風景上。

一開頭的CS5特色影片，則是開始將這樣的原理，運用在建築物的圖片修補當中。雖然目前這個濾鏡都還是比較適合針對無機物或風景使用，但是對於一些圖片修補的步驟已經大幅縮減許多了。

A friend of mine posted two days before there will be a new feature in Photoshop CS5, you can do a number of irregularly shaped objects or automatic stretch and compensation, in fact, this feature in CS4 is also known as the Content-aware Scaling.

In 2007, Shai Avidan and Ariel Shamir in the fairly well-known computer graphics computing SIGGRAPH conference which was published first in the Gimp graphics software was implemented in the technology, launched a group called Liquid Rescale the Plugin, Adobe was one of the hired on people, which in the CS4 launch Content-aware Scaling.

The principle of this filter is mainly applied to the fractal based, but in here to skip the first complex mathematical formulas, a look at the text description for the fractal, from the wiki, or a brief description here can learn:

【 "Fractal Geometry" (fractal) is a new math, it can handle irregular, amorphous and complex graphics, such as tree branches, coastline, animal horns, the river forks, mountain, snail shell diagram , cloud shapes, leaves, lightning and other shapes, with our learned Euclidean geometry, can not account for these special shapes, but the appearance of nature extremely complex and irregular patterns, are able to fractal geometry learn to be explained.

Fractal self-similarity, "self-similarity" refers to any portion of a graphical zoom in or out, you can still show the original patterns, but also refers to the overall graphics and some graphics have a similar pattern. Therefore, the fractal graphics infinite zoom, there will be very similar to the original graphic image. There are many forms of nature have fractal nature, cutting forests or mountain landscape photo of a certain part of its attached to another on the landscape photos, you often do not damage the impression that we have photos, which is a similarity owned by the shape and graphics features. 】

To know the nature of the fractal, you can begin to explain the use of the calculus of this filter.

First, a landscape like this map, the human eye seems there are many non-repetitive.

However, it's processed through the high-contrast, you can find into account the fact that there are still fractal distribution of similarity exists.

And this filter by the use of the place is that it will go automatically calculate this type of fractal distribution of photos of them, so in the process of telescopic pull-release, it will make automatic compensation of the action, so the human eye looks not easily detected flaws, while in the CS4 them, mostly used in the landscape.

CS5 the beginning of a feature film, it is beginning to such a principle, used in building the picture mend. Although there are still quite suitable for this filter for inorganic or landscape use, but for some image repair a number of steps have been substantially reduced.