Part 1 of 2:
The purpose of this article is to help you avoid making costly mistakes when purchasing High definition (HD) products and accessories. High definition (HD) video and high definition television have become very popular in recent years. The letters “HD” are now standard lingo among electronics, computers, components, and everyday life. You see the term “HD” everywhere now. The “HD” term brings a wealth of many technical terms and technical verbiage that can be very confusing. Terms such as “480i”, “1080p”, and “aspect ratio” are often used in advertisements. These types of technical terms are commonly misunderstood by the average consumer. This article will explain everything you need to know about “HD” and the technical lingo that is associated with high-definition video. You will be able to make an informed purchase decision on your next high definition product.
Commercials, advertisements, and staff at major stores often talk about many different technical terms all at one time, often confusing beginners.
To understand all of the technical terms we are going to separate this discussion into these categories:
1. Resolution & Definition
2. Screen size & Aspect Ratio
3. Signal Types.
5. Media (VCR, DVD, Blu-Ray)
Resolution & Definition:
Pixel – Is the smallest portion of the TV or digital camera that lights up and is the smallest portion that makes the video or picture on the screen. There are thousands of them that make up the picture.
The terms “resolution” and “definition” refer to the exact same thing. The term “resolution” commonly refers to still photos and cameras. The term “definition” is the term commonly used when referring to video or motion picture. Both terms “resolution” and “definition” refer to the number of pixels that are used to produce the video or still picture. The more the pixels the higher (definition) quality the video is. It is important to know that resolution and definition has NOTHING to do with the screen size. Both of these terms refer only to the number of pixels that make up video or pictures of a FIXED size. The more pixels that are used to create the video or camera picture of a fixed size, the higher the resolution of the photo and the higher the definition of the video. Increasing the resolution or definition is more noticeable in larger photos and larger video screens then smaller.
Megapixel – This term is generally associated with digital cameras and camera phones. A Megapixel is the number of pixels measured in millions. A 3 megapixel camera would have 3 million pixels. A 6.3 megapixel camera would have 6.3 million pixels or 6,300,000 pixels. You generally would want a higher megapixel rating if you plan on printing large photos. Higher megapixel ratings are less noticeable in small pictures and more noticeable in larger photos.
Standard Definition – Is sometimes referred to as “SD”. It is also referred to as “480i” or “480p”. Standard definition is the number of pixels that is and was always used in video and television prior to the High Definition (HD) craze. Standard definition was adopted sometime in the 1950’s and remains the same today. The resolution of standard definition is 720 pixels from left to right and 480 pixels from top to bottom (720×480). For widescreen the definition is 960 pixels from left to right and 480 pixels from top to bottom (960×480). It is important to note that although widescreen has more pixels, the picture size also increases. This is why widescreen is not to be confused with High Definition. The resolution of widescreen remains the same because the picture size increases along with the number of pixels.
High Definition – Is referred to as “HD” or “HI-DEF”. It is also referred to as “720p”, “1080i”, and “1080p”. It is simply a video of a fixed size that contains more pixels (higher resolution) then Standard Definition of the same video size. The common High Definition resolutions are (1280×720), (1920×1080). As discussed earlier the second number is the number of pixels in the top to bottom direction of the video. So when you see the term “720p” on any type of electronics they are referring to video resolution of 1280×720. If you see the terms “1080i” or “1080p” on any piece of electronics, the resolution is 1920×1080 pixels. Lastly if you see the term “480i” or “480p” they are referring to a resolution of 720×480. As discussed earlier “480i” and “480p” refer to Standard Definition.
Screen size & Aspect Ratio
The screen size is simply the size of the TV screen measured diagonally from corner to corner.
It is important to understand that the Aspect Ratio has NOTHING to do with the resolution nor does it have any thing to do with High Definition. There are only two (2) aspect ratios that you need to understand. The first is known as 4:3 and the second is called 16:9. The 4:3 aspect ratio is the aspect ratio that has been is use since the beginning of TV and still in use today. The 16:9 aspect ratio is commonly referred to as “widescreen”. Although the 4:3 aspect ratio has been in use the longest, the 16:9 ratio has recently became popular when flat panel, plasma, and LCD TVs were put on the market. Nowadays just about every flat panel TV, computer monitor, and video recording device is capable of handling the 16:9 aspect ratio. The 16:9 aspect ratio is simply the same as the 4:3 ratio except that the 16:9 displays a video that is 33% wider then the 4:3. The old picture tube TVs can only display 4:3 aspect ratio videos. They will cut the sides of the picture off when displaying 16:9 video.
How The Aspect Ratio Is Determined:
It is important to understand that the aspect ratio gets measured from two (2) different places. The first place is the TV or monitor screen. The aspect ratio of the TV or monitor screen is determined by taking the measured width of the screen and dividing it by the measured height. The second place the aspect ratio is measured is within the video itself. The aspect ratio of the video is determined by taking the left to right resolution and dividing it by the top to bottom resolution. For example if you have a HI-DEF video that is 1920×1080, you would take 1920 and divide it by 1080. This will give you the number 1.77. If you take the other HI-DEF video that has a resolution of 1280×720 you would take 1280 divide by 720. This would also give you the number 1.77. If you take 16 and divide it by 9 you would also get 1.77. This is how the aspect ratio of 16:9 is determined from the TV industry. The 4:3 aspect ratio is not used in conjunction with high definition.
Although 720×480 is always considered as standard resolution, only 640×480 is the viewable resolution. The additional 60 pixels in the left to right direction are used for information for the TV. The 4:3 aspect ratio is determined taking 640 divided by 480. This gives you 1.33. If you take 4 divide by 3 you also get 1.33. This is where 4:3 aspect ratio comes from.
There are four signal types that you must understand when buying video electronics.
1. Analog – This is the signal type that was used in VCRs, Cassette tapes, 8-Track Tapes, and records. Up until recently it was the signal format that was broadcasted by TV stations and cable companies. The analog signal format carries unwanted noise and “hiss” in the audio and fuzziness within the video. The digital signal format was introduced in the 1980’s due to its ability to play audio without noise or “hiss” and display video with superior quality. It is important to know that many older music and TV movies were originally recorded using the analog signal format. Producers have made great efforts to convert older music and movies to the digital signal format. Audio and video will only be perfect quality if it was originally recorded in the digital format.
2. Digital – This is the signal type that was introduced in the 1980’s. It became widely known because it was and still is the signal format used by compact discs. It is also the signal format that is used by DVDs, Blu-Ray, and is now the signal type that is broadcasted by TV stations. It has become the standard signal format and has replaced the analog for all TV and computer video components. The digital signal offers superior audio and video quality with no noise, “hiss”, or “fuzz”.
3. “i” – This is the “i” within “480i” and “1080i” that you commonly see on video electronics. It stands for “interlace”. This has nothing to do with the resolution. Interlaced is simply an arrangement of how the different parts of the TV signal are arranged. You will not see any better of a picture when viewing a “1080i” picture vs. a “1080p” picture. Nor will you see any difference in picture quality between a “480i” or “480p” picture. The interlaced signal is simply the oldest of both the “i” and “p” signal types. Interlaced signal types were needed by the old picture tube TV’s and picture tube computer monitors. The interlaced video format has been in use since the beginning of TV. The “p” (progressive) signal types have been introduced to be used for all the flat-panel TV’s and flat-panel computer monitors. Although flat-panel TVs and computer monitors can accept an interlaced signal, the interlaced signal is always converted to the “p” progressive format prior to displaying the picture.
4. “p” – This is the “p” within “480p”, “720p”, and “1080p” that you commonly see on electronic products. The “p” simply stands for “progressive”. This is the newer of the “p” and “i” signal types. The progressive signal was created strictly for use with plasma TVs, LCD TVs, and flat-panel computer monitors. The video that is displayed by flat-panel devices is displayed on the screen in a “progressive” manner. All flat-panel devices convert the incoming “i” (interlaced) signals to the progressive “p” type before displaying the video on the screen. It is important to know that there is NO visual difference within the video quality when comparing the “i” signal type and the “p” signal type.
Be sure to continue on to “Part 2: High Definition (HD) for Dummies & Beginners”. We want to make sure that you are armed with all of the required knowledge so you will make an informed purchase.