Image difference when connecting via VGA, DVI and HDMI
VGA, DVI, and HDMI are video interfaces for transmitting video signals from a source to an image output device. They differ in the method of transmission and signal processing, as well as in the connector.
VGA was developed in 1987 and was intended to transmit an analog signal to cathode ray tube monitors. Ten years later, LCD monitors began to dominate the market.
Via VGA, the process of transmitting a video signal was carried out by converting a digital signal into an analog one, which was then transmitted and displayed on a CRT monitor. With the advent of LCD monitors, design has become more complex. Now it was necessary to convert the signal from digital to analog, transmit it to the LCD monitor, and convert it back to digital. It became obvious that the analog signal could be removed from the chain and in 1999 the DVI video interface appeared.
VGA, DVI, HDMI and miniHDMI
In the early 2000s, HDMI was developed. It differs from DVI in a more compact connector and in the ability to transmit digital audio signals (since 2008, DVI has also learned to transmit sound). The benefits of the new interface were obvious and, at the moment, it is advanced. Its popularity has led to the appearance of varieties such as miniHDMI and microHDMI. Their difference is only in the size of the connectors.
Are DVI and HDMI better than VGA?
The main argument in favor of digital interfaces is that the analog signal is exposed to external electromagnetic fields during transmission and this leads to its distortion. There is some truth to this, but at home there is no serious interference that can cause noticeable distortion, even when transmitting over long distances. DVI and HDMI are also believed to transmit the signal as accurately as possible due to post-error correction, which is not the case with VGA. This is true, but this is an advantage only with a high-quality cable of short length (up to 5 meters).
Another reason in favor of digital video interfaces is the absence of unnecessary signal conversions, from digital to analog and vice versa. It would seem that HDMI and DVI should be better than VGA in this regard. In practice, it sometimes turns out the other way around, since in no case can you do without transformations. Digital signals are encrypted and must be decoded and processed before being displayed on the screen. For this process, separate modules of the image output devices are responsible and their transcoding algorithms are not always ideal. It is true that over time they are improving and are currently at a good level even on cheap monitors and televisions.
VGA, DVI and HDMI connectors
Cable quality is another sticking point. The analog signal is less demanding, while the digital signal needs a good conductor. This is especially true with a cable length of more than five meters. In this case, with a bit loss, the error correction does not always work and in the output we can obtain an image many times worse than if a VGA connection were used.
summarizing
Although I have downplayed the merits of DVI / HDMI, in some cases the image transmitted through them will be better. But you can only notice this if you have a high-quality cable, a reliable connection between the connectors, and a good output device – a monitor or high-definition television.
If your monitor offers a good image via VGA, don’t expect that when connected via a digital video interface the image will shine in new colors. In my practice, I have seen a significant improvement only once when connecting monitors from the company “AOC”. They worked disgustingly via VGA – the picture was blurry, fuzzy. In this case, it’s just the manufacturer’s fault.
