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像素长宽比问题！
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The use of desktop computer based packages like PhotoShop and After Effects to produce both 16:9 and 4:3 graphics has increased dramatically over the last few years.
在最近几年，桌面电脑上的软件诸如PS和AE ，在16:9和4:3图形图象处理领域的应用戏剧化地增长。
Although these packages produce excellent results there are problems transferring the images to video. Maintaining the correct size, shape, colour and luminance levels of a graphic is obviously very important.
然而，即使这些软件工作地非常出色，但是从图象到视频仍然有一些问题。比如，保持正确的尺寸，形状，颜色，流明度方面的问题就明显非常重要。
History
What size is a television picture?
There are 576 active lines in a television picture, making it 576 pixels high. A 4:3 image would therefore be:
历史
电视画面的尺寸是多少？
回答：在电视画面中，有576条动态的扫描线，也就是在高度中有576个象素。因此，一个4:3的画面应该是:
(576 x 4) ÷ 3 = 768 pixels wide.
(576*4)/3=768象素 在“宽”（横向）上
However this assumes the pixels are square - but television pixels are not square. They have an aspect ratio of approximately 1:1.094. A 4:3 television picture would therefore be:
然而这个结果是基于象素是正方形的情况下的---但是电视象素不是正方形的。电视上有一个象素长宽比，大约是1:1.094。所以，一个4:3的电视画面因此应该是:
768 ÷ 1.094 = 702 non-square pixels wide
768/1.094=702 象素（非方形象素的情况下，宽度上）
So a 4:3 television image is 702 pixels wide by 576 high.
所以，一个4:3的电视画面是 702象素 * 576高。
But anyone who has imported graphics from a computer system to the television systems knows the correct width to make the image is 720 pixels! Why - and where did the extra 18 pixels come from?
但是任何一个从电脑系统导入到电视系统的人，都知道建立正确图象的宽度上应该是720象素！为什么有这额外的18个象素---以及这18个象素从哪里来的？
Digital pictures are effectively wider than analogue pictures by 18 pixels but the 4:3 image sits inside the 720 by 576 area. The additional 18 pixels are required for digital processing and it would be perfectly acceptable to leave them black - but if the image is shrunk via a digital DVE, two 9 pixel wide black stripes will be seen at the sides.
在最近几年，桌面电脑上的软件诸如PS和AE ，在16:9和4:3图形图象处理领域的应用戏剧化地增长。
Although these packages produce excellent results there are problems transferring the images to video. Maintaining the correct size, shape, colour and luminance levels of a graphic is obviously very important.
然而，即使这些软件工作地非常出色，但是从图象到视频仍然有一些问题。比如，保持正确的尺寸，形状，颜色，流明度方面的问题就明显非常重要。
History
What size is a television picture?
There are 576 active lines in a television picture, making it 576 pixels high. A 4:3 image would therefore be:
历史
电视画面的尺寸是多少？
回答：在电视画面中，有576条动态的扫描线，也就是在高度中有576个象素。因此，一个4:3的画面应该是:
(576 x 4) ÷ 3 = 768 pixels wide.
(576*4)/3=768象素 在“宽”（横向）上
However this assumes the pixels are square - but television pixels are not square. They have an aspect ratio of approximately 1:1.094. A 4:3 television picture would therefore be:
然而这个结果是基于象素是正方形的情况下的---但是电视象素不是正方形的。电视上有一个象素长宽比，大约是1:1.094。所以，一个4:3的电视画面因此应该是:
768 ÷ 1.094 = 702 non-square pixels wide
768/1.094=702 象素（非方形象素的情况下，宽度上）
So a 4:3 television image is 702 pixels wide by 576 high.
所以，一个4:3的电视画面是 702象素 * 576高。
But anyone who has imported graphics from a computer system to the television systems knows the correct width to make the image is 720 pixels! Why - and where did the extra 18 pixels come from?
但是任何一个从电脑系统导入到电视系统的人，都知道建立正确图象的宽度上应该是720象素！为什么有这额外的18个象素---以及这18个象素从哪里来的？
Digital pictures are effectively wider than analogue pictures by 18 pixels but the 4:3 image sits inside the 720 by 576 area. The additional 18 pixels are required for digital processing and it would be perfectly acceptable to leave them black - but if the image is shrunk via a digital DVE, two 9 pixel wide black stripes will be seen at the sides.
数字图象比同类，类似的图象（此处翻译暂时有点小问题)要宽18个象素，但是实际上，4:3图象是基于在720*576的区域的。这额外的多出来的18个象素是由于数字合成处理的需要，并且这些象素会是黑色的（因此能够被接受）--但是一旦图象通过一个数字编辑系统被缩小了，两个9个象素的宽度上的黑条就会在边上被看到。
The new BBC Testcard (Testcard J) shows these extra pixels:
这些新的BBC的Testcard (Testcard J) (Compressed tiff file 1050 by 576)显示出了这些额外的象素。
Old Testcard edge New Testcard J edge
These 18 pixels are of course not square, converting them to square pixels gives:
这些18个象素当然不是正方形的，把他们转换成方形的象素得到以下结果
18 x 1.094 = 20 square pixels
18*1.094=20方形的象素
When making a 4:3 graphic on a square pixel device for conversion to a 720 by 576 (non square pixel) video image, the width of the 768 by 576 (square pixel) image must be increased to:
在基于一个方形象素设备上制作一个4:3图象为了转换成一个720*576(非方象素)的视频图象的情况下，768*576(方形象素)必须增加到以下结果
768 + 20 = 788 square pixels
768+20=788方形象素
making the 4:3 the square pixel graphic 788 by 576
建立4:3的方形象素图象尺寸应该是788*576
These additional pixels are not taken into account when calculating the aspect ratio, but without them images transferred between systems will not be the correct shape.
这些附加的象素在计算图象象素长宽比的情况下是不被计算进去的，但是离开这些象素，在系统间转换的图象将得不到正确的图形。
The new BBC Testcard (Testcard J) shows these extra pixels:
这些新的BBC的Testcard (Testcard J) (Compressed tiff file 1050 by 576)显示出了这些额外的象素。
Old Testcard edge New Testcard J edge
These 18 pixels are of course not square, converting them to square pixels gives:
这些18个象素当然不是正方形的，把他们转换成方形的象素得到以下结果
18 x 1.094 = 20 square pixels
18*1.094=20方形的象素
When making a 4:3 graphic on a square pixel device for conversion to a 720 by 576 (non square pixel) video image, the width of the 768 by 576 (square pixel) image must be increased to:
在基于一个方形象素设备上制作一个4:3图象为了转换成一个720*576(非方象素)的视频图象的情况下，768*576(方形象素)必须增加到以下结果
768 + 20 = 788 square pixels
768+20=788方形象素
making the 4:3 the square pixel graphic 788 by 576
建立4:3的方形象素图象尺寸应该是788*576
These additional pixels are not taken into account when calculating the aspect ratio, but without them images transferred between systems will not be the correct shape.
这些附加的象素在计算图象象素长宽比的情况下是不被计算进去的，但是离开这些象素，在系统间转换的图象将得不到正确的图形。
