What is Deinterlacing? Facts, solutions, examples
本博文由Alex Sen翻译自网站http://www.100fps.com。不保证会有机会全文翻译。
博文适合希望做视频反交错的同学学习。特别适合入门的学习。文章反交错举例丰富，是广大Ripper和拍客反交错问题的福音。
正文：（译文字数：1100）
This site shows you how to make brilliant looking DivX video (from TV, DVB, DV, DVD etc) for archiving purposes OR how to reduce file size to produce
就由本站来告诉你怎样利用来自TV，DVB，DV，DVD等片源制作才华横溢的DivX视频从而表现表现自己，也能让你学习压缩视频大小，以小视频来
good-looking yet small DivX footage.
表现不俗的画面张力。
If you are dealing with DivX, this site features a few video statistics and experiments, that may be of some interest for all video publishers and DivX
如果你正在与DivX打交道，本网站以少量的视频信息统计和实验为特点，这也许是所有视频压制家们与DivX爱好者
enthusiasts.
趋之若鹜的好东东呀。
A great part of this site deals with interlacing/deinterlacing which introduces some of the nastiest interlacing problems like these:
我们引以为豪的就是处理各种经典的反交错问题及介绍各种交错，像这样：
Resized before deinterlaced 1
缩放画面在反交错前面完成 1
Resized before deinterlaced 2
缩放画面在反交错前面完成 2
Not resized and not deinterlaced
不进行缩放与反交错
Deinterlaced properly
正确的反交错
Well, read on.
咳，再往下读读吧。
Some definitions and explanations
概念与解释齐飞
Do you think you record 25 frames per second when you make a movie with your digital camcorder?
你有木有想过用你自己的数码摄像机来拍摄每秒25帧的视频？
Not quite.
差不多，会有的吧。
Your digital camcorder does the following:
数码摄像机会这样做：
Records 50 pictures per second, intermixing every 2 consecutive pictures (with half the height) into 1 frame.
每秒拍下50张图片，混合所有连续的两张图片（每张只有一半的高度）从而形成1帧。
In fact, you don’t call them pictures, but fields. So 2 fields are mixed into 1 frame.
This mixing is called interlacing.
事实上，那些不应该称为图片，而是“场”。所以说，两场混合成一帧。这种混合我们叫它：交错。
So this is the timeline of your digital camcorder or digital television
那么接下来就是你数码摄像机或者数码电视的工作流程啦，看看吧：
1) Record field 1
获取第一场
2) Record field 2
获取第二场
3) Mix (=interlace) field 1 and field 2 into one frame and save the frame as frame 1.
混合（=交错）场一和场二形成一帧并将此帧存储为第一帧。
4) Record field 3
获取第3场
5) Record field 4
获取第4场
6)
Mix (=interlace) field 3 and field 4 into one frame and save the frame as frame 2.
混合（=交错）场3和场4形成一帧并将此帧存储为第2帧。
Note: The timeline of your analog camcorder is usually different. Analog camcorders, VCRs etc do not mix the recorded pictures. They record picture after picture after picture. Analog
注意：模拟摄像机（那些用实物记录信息的）的工作流程通常是不同的。模拟摄像机，像盒式磁带录象机这样的不是混合所记录的图像。它们是一幅接着一幅记录图像的。
camcorders use “odd” and “even” sets of scan lines, too, but they don’t intermix them into 1 frame.
模拟摄像机虽然也是用“奇数”和“偶数”来设置扫描线的，但它们并不交错场为一帧。
One could use the term 50 images per second (50 ips), to emphasize, that both analog and digital recorders are capturing 50 times per second.
有些人称之为每秒用一组50张图像（50 ips，即每秒50场），需要强调的是，不管是模拟的还是数码的，它们每秒都是记录50次图像信息。
The digitalizers nowadays (e.g. Hauppauge WinTV) capture 25fps=50 fields per second, so in the end on your harddisk it makes no difference to say 25 (interlaced) digital frames per
现在的数码设备（像Hauppauge WinTV）是每秒显示25帧/50场的，所以你磁盘里的每秒25（交错）“数码”帧
second or 50 not interweaved analog fields per second. But there IS a difference.
和每秒50未反交错“模拟”场是看着是一样一样的。但是，确实是有区别。
So the timeline of the analog camcorder is/was:
最后，模拟摄像机的工作就是这样：
1) Record field 1 (=frame 1) (odd scan lines)
记录场一（=帧一）（扫描奇数行）
2) Record field 2 (=frame 2) (even scan lines)
记录场二（=帧二）（扫描偶数行）
3) Record field 3 (=frame 3) (odd scan lines)
记录场三（=帧三）（扫描奇数行）
4) Record field 4 (=frame 4) (even scan lines)
记录场四（=帧四）（扫描偶数行）
Here is an example of what your digital camcorder does:
这里就是你数码摄像拍摄的图例：
Capture field1 (captures at half the height, or full height and then resizes down):
获取场1（只获取一半的高度，或全高而后缩放为一半）：
Capture field2:
获取场2：
They pretty much look the same. But wait, they ARE different. You can see by comparing the position of the thumb and the keyboard
它们看起来的确相当相似。不过别急，它们确实是不同的。你可以比较比较拇指与键盘的相对位置的变化从而看到
keys.
变化。
Now these two fields are mixed (=interlaced) into Frame1 (full height):
现在，这两场被混合（=交错）成帧一了（完整高度）
What you see above is an exact frame as on tape of your camcorder.
你所看到的上图就是摄像机生成的一帧。
Here is a zoomed view of the above Frame 1:
这是帧一局部的放大：
As you can clearly see above, Frame1 consists of Field1 and Field2.
你能清晰的从上图看出，帧一是由场一和场二组成的。
The way it looks is called saw tooth type edge distortion = mice teeth = combing = serrations = interlaced lines.
看到的图像特征我们叫它 锯齿边缘=老鼠齿=梳齿=锯齿状=交错线。