为什么HDMI-DVI可以提供比VGA更清晰的图像？

With all the great hardware we have available these days, it seems we should be enjoying great quality viewing no matter what, but what if that is not the case? Today’s SuperUser Q&A post seeks to clear things up for a confused reader.

如今，借助我们拥有的所有出色硬件，似乎无论如何我们都应该享受高质量的观看，但是如果不是这样的话，该怎么办？ 今天的“超级用户”问答页面旨在为困惑的读者弄清一切。

Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.

今天的“问答”环节由SuperUser提供，它是Stack Exchange的一个分支，该社区是由社区驱动的Q＆A网站分组。

Photo courtesy of lge (Flickr).

照片由lge(Flickr)提供 。

问题 (The Question)

SuperUser reader alkamid wants to know why there is a noticeable difference in quality between HDMI-DVI and VGA:

超级用户阅读器alkamid想知道为什么HDMI-DVI和VGA在质量上有明显的区别：

I have a Dell U2312HM monitor connected to a Dell Latitude E7440 laptop. When I connect them via laptop -> HDMI cable -> HDMI-DVI adaptor -> monitor (the monitor does not have a HDMI socket), the image is much sharper than if I connect via laptop -> miniDisplayPort-VGA adaptor -> VGA cable -> monitor.

我有一台Dell U2312HM显示器连接到Dell Latitude E7440笔记本电脑。 当我通过笔记本电脑-> HDMI电缆-> HDMI-DVI适配器->显示器(显示器没有HDMI插座)连接它们时，图像比通过笔记本电脑-> miniDisplayPort-VGA适配器-> VGA时要清晰得多。电缆->显示器。

The difference is difficult to capture with a camera, but see my attempt at it below. I tried playing with the brightness, contrast, and sharpness settings, but I cannot get the same image quality. The resolution is 1920*1080 with Ubuntu 14.04 as my operating system.

区别很难用相机捕捉，但请参阅下面的尝试。 我尝试使用亮度，对比度和清晰度设置，但无法获得相同的图像质量。 分辨率为1920 * 1080，使用Ubuntu 14.04作为操作系统。

VGA:

VGA：

HDMI:

HDMI：

Why is the quality different? Is it intrinsic to these standards? Could I have a faulty VGA cable or mDP-VGA adaptor?

为什么质量不同？ 这些标准是固有的吗？ VGA电缆或mDP-VGA适配器有问题吗？

Why is there a difference in quality between the two?

为什么两者之间的质量有所不同？

答案 (The Answer)

SuperUser contributors Mate Juhasz, youngwt, and Jarrod Christman have the answer for us. First up, Mate Juhasz:

超级用户贡献者Mate Juhasz，youngwt和Jarrod Christman为我们找到了答案。 首先，伴侣Juhasz：

VGA is the only analog signal among the ones mentioned above, so it is already an explanation for the difference. Using the adapter can further worsen the quality.

VGA是上述信号中唯一的模拟信号，因此已经是差异的解释。 使用适配器会进一步降低质量。

Some further reading: HDMI vs. DisplayPort vs. DVI vs. VGA

进一步阅读： HDMI与DisplayPort与DVI与VGA

Followed by the answer from youngwt:

随后是youngwt的回答：

Assuming that brightness, contrast, and sharpness are the same in both cases, there could be two other reasons why the text is sharper with HDMI-DVI.

假设两种情况下的亮度，对比度和清晰度都相同，则可能还有其他两个原因使HDMI-DVI的文本更清晰。

The first has already been stated, VGA is analog, so it will need to go through an analog to digital conversion inside the monitor. This will theoretically degrade image quality.

第一个已经说明过，VGA是模拟的，因此它将需要在显示器内部进行模数转换。 理论上这将降低图像质量。

Second, assuming that you are using Windows, there is a technique called ClearType (developed by Microsoft) which improves the appearance of text by manipulating the sub pixels of an LCD monitor. VGA was developed with CRT monitors in mind and the notion of a sub pixel is not the same. Because of the requirement for ClearType to use an LCD screen and the fact that the VGA standard does not tell the host the specifications of the display, ClearType would be disabled with a VGA connection.

其次，假设您使用的是Windows，则存在一种称为ClearType(由Microsoft开发)的技术，该技术通过操纵LCD监视器的子像素来改善文本的外观。 VGA是在考虑CRT监视器的情况下开发的，子像素的概念并不相同。 由于要求ClearType使用LCD屏幕，并且VGA标准不能告知主机显示器的规格，因此将通过VGA连接禁用ClearType。

I remember hearing about ClearType from one its creators on a podcast for This().Developers().Life() IIRC, but this Wikipedia article also supports my theory. Also HDMI is backward compatible with DVI and DVI supports Electronic Display Identification (EDID).

我记得在IIRC的Podcast上从其创建者那里听说过ClearType，但这篇Wikipedia文章也支持我的理论。 HDMI也向下兼容DVI，并且DVI支持电子显示识别(EDID)。

With our final answer from Jarrod Christman:

在Jarrod Christman的最终答复中：

The others make some good points, but the main reason is an obvious clock and phase mismatch. VGA is analog and subject to interference and mismatch of the analog sending and receiving sides. Normally one would use a pattern like this:

其他的都有一些优点，但是主要原因是明显的时钟和相位不匹配。 VGA是模拟的，容易受到模拟发送和接收端的干扰和不匹配。 通常，人们会使用这样的模式：

Clock and Phase

时钟和相位

Then adjust the clock and phase of the monitor to get the best match and the sharpest picture. However, since it is analog, these adjustments may shift over time, and thus you should ideally just use a digital signal.

然后调整显示器的时钟和相位，以获得最佳匹配和最清晰的图像。 但是，由于它是模拟信号，所以这些调整可能会随时间推移而变化，因此理想情况下，您应该只使用数字信号。

Have something to add to the explanation? Sound off in the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.

有什么补充说明吗？ 在评论中听起来不错。 是否想从其他精通Stack Exchange的用户那里获得更多答案？ 在此处查看完整的讨论线程 。

翻译自: https://www.howtogeek.com/214661/why-does-hdmi-dvi-provide-a-sharper-image-than-vga/