神奇的图像处理算法(Amazing algorithms to enhance or transform images)

1 神奇的图像处理算法 

        这是利用数学算法，进行高难度图像处理的一个例子。事实上，图像处理的数学算法，已经发展到令人叹为观止的地步。

Scriptol列出了几种神奇的图像处理算法，让我们一起来看一下。

1.1 像素图生成向量图的算法

数字时代早期的图片，分辨率很低。尤其是一些电子游戏的图片，放大后就是一个个像素方块。 Depixelizing算法可以让低分辨率的像素图转化为高质量的向量图。

1.2 黑白图片的着色算法

让老照片自动变成彩色的 算法。

1.3 消除阴影的算法

不留痕迹地去掉照片上某件东西的阴影的 算法。

1.4 HDR照片的算法

所谓"HDR照片"，就是扩大亮部与暗部的对比效果，亮的地方变得非常亮，暗的地方变得非常暗，亮暗部的细节都很明显。
实现HDR的软件有很多，这里推荐 G'MIC。它是GIMP图像编辑软件的一个插件，代码全部开源。

1.5 消除杂物的算法

所谓"消除杂物"，就是在照片上划出一块区域，然后用背景自动填补。 Resynthesizer可以做到这一点，它也是GIMP的一个插件。

1.6 自动合成照片的算法

根据一张草图，选择原始照片，然后把它们合成在一起，生成新照片。这是清华大学的科研 成果。

1.7 美容算法

  自动对容貌进行"美化"的 算法。

2 Amazing algorithms to enhance or transform images

List of algorithms for image processing whose level of intelligence avoids infinitely complex tasks.
From the simplest to more complex ones...

2.1 Depixelizing images

Starting from a raster image that is made of large squares, we arrive at a clearer picture, 

as if one could a posteriori change the definition of the screen on which it was drawn ...

This can be very useful if one wants to convert an old game on a modern platform such as 

Canvas or a smartphone.

See article depixelizing. Implemented by Scale2x (on Sourceforge). 

HQX is a similar super resolution command line tool to enlarge images.

2.2 Color a black and white image

This technique is so well controlled that we can now see in color old black and white films.

It is explained in an article, Colorization Using Optimization giving several examples.

2.3 Restore a picture or make a HDR

Wisely by removing the "noise", ie the image defects such as dots and stripes, 

and it needs to know to interpret that, the algorithm gives life to a cliche damaged or washed out.

It is implemented in a plugin for Gimp, G'Mic. 

It can also automatically make HDR, ie increase the brightness of light areas and darken the dark parts.

2.4 Turn a photo into drawing

This algorithm is implemented in G'Mic too.

Used from the command line, G'Mic allows many changes examples of which can be seen in the gallery.

2.5 Seam carving

Intelligent algorithm to resize images maintaining the appearance of objects within it.

 It is actually implemented in the resizing functions of the main graphical utilities like Gimp

 with the Liquid Rescale plugin, ImageMagick with the -liquid-rescale option.

Seam Carving for Content-Aware Image Resizing.

2.6 Remove an object

It reached the highest level. From a rough outline of the object to remove on an image, 

and this may be a person like everything else, the algorithm is able to identify itself the object in question, 

to define its exact boundaries, to extrapolate what would be the background if the object had not been present, 

and restore the background all that without any human intervention.

This algorithm is available both as a Gimp plugin to install or in Photoshop.

2.7 Compose a picture

By drawing a sketch and then combining objects drawn in a simplistic way to photos, 

it manages to produce a new image that incorporates natural objects as though they were photographed.

This algorithm is implemented in the software Sketch To Photo. From the article, 

you can download the command line program.

2.8 Beautify a face

There is no written rule to define whether a face is beautiful or if it is not, 

then the creators followed the principle that what is more closer to the common is better.

You judge yourselves t by comparing the two versions of the same face on the photo,

 with the original face at left and at right as amended by the computer.

The algorithm has an augmented reality application, in conjunction with a technology that combines a camera 

with glasses to project an image of a modified reality on the glasses.

More information about this esthetic trick algorithm.


英文原版来源：
http://www.scriptol.com/programming/graphic-algorithms.php 作者：Scriptol
中文翻译来源：
http://www.ruanyifeng.com/blog/2011/08/amazing_algorithms_of_image_processing.html 翻译者：阮一峰