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Projector Glossary: Master the Technical Terms

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From aspect ratio to zoom: the home theater projector glossary demystifies the technical terms for you in plain English.

Are you thinking of buying a home theater projector but feeling overwhelmed by the technical jargon?

With so many options on the market, it can be challenging to understand what all the different terms mean and which features you really need.

That’s why I’ve put together this home theater projector glossary of common terms to help you make an informed decision. From aspect ratio to zoom, you’ll learn everything you need to know in clear and simple language.

The introduction to home theater projectors gives plenty of detail on the features to look for once you’re comfortable with the terminology.

So, whether you’re a first-time buyer or a seasoned pro, read on to discover the essential features of a home theater projector.

Check out the entire home theater glossary for a complete list of technical terms about other aspects of home theater.

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1080p is a way to describe the clarity of the image produced by a projector. It means the picture has 1920 horizontal pixels and 1080 vertical pixels, which results in a very clear and sharp image. The term is often used to describe high-definition pictures. It is often called 1920x1080 and has a 16:9 aspect ratio.
4K is a term used to describe the resolution of a projector's image. In this case, the number 4K refers to the horizontal resolution of the image, which is approximately 4000 pixels. A 4K projector has a resolution of 3840 horizontal pixels and 2160 vertical pixels (3840x2160), providing a high-quality image with sharp details and vivid colors. This resolution is four times that of 1080p, resulting in an even more immersive viewing experience.
8K is known as ultra-high definition and has a resolution of 7680 horizontal pixels and 4320 vertical pixels (7680x4320). It has four times as many pixels as 4K and sixteen times as many pixels as 1080p. This means that an 8K projector can produce a much clearer and more detailed image than a 4K or 1080p projector, but it requires a larger screen and higher processing power to display the full potential of the resolution. However, 8K projectors are currently very expensive and may not be suitable for all viewing environments.


Acoustic Transparency
Acoustic transparency is a projector screen technology that allows sound to pass through the material instead of being blocked like in a traditional screen. This makes it possible to place speakers behind the screen, creating a more natural and immersive audio experience. Acoustic Transparency screens use a special material with tiny holes, allowing sound to travel through without affecting the quality or volume of the audio. This technology is particularly useful in home theater setups where audio quality is a top priority, and there is limited space to place the speakers.
Ambient Light Rejection (ALR)
An ALR is a type of screen designed to make it easier to see a projected image in a room with lots of light. The screen reflects light in a specific direction, making the projected image brighter and clearer. This is useful in rooms where it's hard to control the lighting, like a living room with windows or lights on. ALR screens are often more expensive than traditional screens but can make a big difference in the quality of the projected image.
Anamorphic Lens
An anamorphic lens is a special lens used with some home theater projectors to show movies in their original widescreen format without black bars or distortion. It squeezes the wider movie image into a smaller space on the projector's image sensor. Then it stretches it back out to its original size on the screen. Without the anamorphic lens, the movie would either have black bars or be stretched and distorted. Using an anamorphic lens can give a better viewing experience for movies with wider aspect ratios, but it may be more expensive and require professional installation.
ANSI Lumens
ANSI lumens are a way to measure the brightness of a home theater projector and are named after the American National Standards Institute (ANSI). The higher the ANSI Lumens rating, the brighter the projector will be. This is important to consider when choosing a projector for your home theater, especially if your room has a lot of ambient light or a large screen. However, brightness is not the only factor to consider when choosing a projector. Other factors, such as contrast, color accuracy, and resolution, should also be considered.
Aspect Ratio
The aspect ratio of a projector refers to the ratio of the width of the projected image to its height and determines the shape and size of the image shown on the screen. The projector screen also has an aspect ratio and will ideally match the image's shape. Typical aspect ratios for projectors and screens are 21:9, 16:10, 16:9 and 4:3. A widescreen projector might have a rectangular 16:9 aspect ratio, while an older model might have a more square-shaped aspect ratio of 4:3.


Black Level
The black level of a projector refers to how dark the black areas of an image appear on the screen. The black level is affected by several factors, including the quality of the projector's light source, the contrast ratio of the projector, and the type of screen being used. A good black level is vital for achieving a high-quality picture, especially in dark scenes with many shadows. A projector with an excellent black level can produce deeper, more detailed blacks and better contrast, making the image look more vibrant and realistic.


The chipset is a key projector component that processes the video signal and generates images on the screen. Common projector chipsets are LCD, DLP and LCoS. The different chipsets have various pros and cons, which might affect the projector you buy.
Color Gamut
Color gamut refers to the range of colors that a projector can display. It is usually measured using the CIE 1931 color space, a mathematical model describing how humans perceive color. A projector with a limited color gamut may not reproduce the full range of colors in a movie or video game, resulting in less vibrant and less realistic images. As part of the 4K UHD specification, BT.2020 introduced a wide color gamut, meaning 4K projectors could display many more colors than older 1080p models.
Color Temperature
Color temperature is a standard of how "warm" or "cool" the colors in the projected image appear and is measured in degrees Kelvin (K). The color temperature setting of a projector adjusts the balance between blue and yellow tones in the picture. A lower color temperature produces a warmer, yellowish image, while a higher temperature produces a cooler, bluish image. The color temperature setting is crucial because it can affect the perceived color accuracy of the picture. Many projectors adjust the color temperature to ensure accurate and consistent colors across different lighting conditions.
Contrast Ratio
The contrast ratio is the difference between the brightest and darkest parts of the image. The higher the contrast ratio, the better the projector displays details in the image's bright and dark areas. This is important for creating a more immersive viewing experience, especially in dark environments. It's important to note that the contrast ratio is not the same as brightness, which is measured in lumens.


DLP stands for Digital Light Processing, a type of projector technology that uses tiny mirrors to reflect light and create an image on a screen. DLP projectors have many advantages, such as high contrast ratios, fast response times, no color wheel artifacts and compact size. They are commonly used in home theaters and portable projectors.
Dynamic Iris
A dynamic iris is a feature in some projectors that improves the image's contrast and black level. It works by adjusting the amount of light passing through the lens based on the projected image's brightness. This feature helps create more realistic and immersive movie experiences. However, not all projectors have a dynamic iris, and its usefulness depends on your room's lighting conditions and screen size.


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Fan Noise
Fan noise refers to the sound that comes from the cooling fan in a projector. Some projectors have quieter fans or offer a "quiet mode" to reduce fan noise, while others may have louder fans that cannot be adjusted. Fan noise can be distracting during quiet moments of a movie or video game, so it's important to consider the noise level of a projector's fan when buying a projector.
Foot-lamberts are a unit of measurement for the brightness of a projected image on a screen. It tells you how much light is reflected from a 1-foot by 1-foot area of the screen and is helpful as a guide to the required amount of light in different viewing conditions.


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HDMI stands for High-Definition Multimedia Interface and is a way to connect your projector to other devices like a Blu-ray player or laptop. It's a digital connection that carries high-quality audio and video signals, and it's easy to use because you only need one cable. Most projectors come with at least one HDMI port. However, different standards, like HDMI 1.4, HDMI 2.0, and HDMI 2.1, support different features and video formats.
HDR (High Dynamic Range) is a technology that makes the images projected by a projector look more realistic and vivid. It expands the range of brightness, contrast, and color a projector can display, resulting in a more immersive and enjoyable viewing experience. HDR content is becoming more common, so choosing a projector that supports HDR is important if you want to take full advantage of the new technology. There are different levels of HDR, ranging from basic HDR10 to more advanced formats like Dolby HDR10+, Vision and HLG (Hybrid Log-Gamma). When choosing a projector with HDR, it's important to ensure that it supports the specific HDR format used by the content you plan to watch.


Image Processing
Image processing in a projector refers to the various techniques used to enhance the picture quality of the projected image. These techniques can include adjusting the color, contrast, sharpness, and other elements of the image to improve its clarity and overall appearance. Image processing aims to produce a clear, vibrant, and realistic picture on the screen, which can significantly enhance the viewing experience.
Input Lag
Input lag is the delay between when a signal is sent to a projector and when it is displayed on the screen. It can be measured in milliseconds and is often a concern for gamers or anyone who wants a responsive and smooth experience. Lower input lag means less delay between your actions and the visuals on the screen. High input lag can cause problems like stuttering, lagging, or a lack of synchronization between sound and image.
Input Ports
Input ports on a projector are the physical connections that allow you to connect different devices, such as a laptop, gaming console, or Blu-ray player. The most common input ports on a projector are HDMI, VGA, and USB, but other types of ports may also be available, like component and composite video. The more input ports a projector has, the more devices you can connect to it simultaneously, making it more versatile and convenient to use.


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Keystone Correction
Keystone correction is a feature in projectors that helps to fix the distortion that occurs when the projector is not placed directly in front of the screen or is tilted upwards or downwards. It adjusts the image to make it rectangular and proportional to the screen. This feature is useful when there is limited space to position the projector or the screen is not at the same height as the projector. Keystone correction can be done manually or automatically through the projector's settings.


Lamp Life
Lamp life is a term used for projectors to describe the duration that the projector's lamp can be used before it needs to be replaced. The lamp life is typically measured in hours and can vary depending on the projector model, usage, and quality of the lamp. Keeping track of a projector's lamp life is vital, as a failing lamp can lead to dimming, color distortion, or even complete failure.
LCD stands for Liquid Crystal Display and refers to a type of technology used in projectors to create images. LCD projectors use a bright light source to shine light through panels of liquid crystals. These panels have millions of tiny pixels that can be manipulated to control the light that passes through, creating different shades and colors. LCD projectors are known for producing bright, clear images with accurate color reproduction and low response times, making them suitable for gaming.
LCoS stands for Liquid Crystal on Silicon, a technology some projectors use to produce high-quality images. Using a combination of LCD and DLP techniques, LCoS projectors use a tiny reflective surface covered with liquid crystals to reflect and control light, which allows for sharp and detailed images. They are known for producing deep blacks and vivid colors, making them a popular choice for home theater enthusiasts, although they are expensive.
Lens Memory
Lens memory is a feature in some high-end projectors allowing users to save different zoom and focus settings for various aspect ratios and screen sizes. With lens memory, users can easily switch between different aspect ratios (such as 16:9 and 2.35:1) without manually adjusting the zoom and focus every time. This feature is handy for home theater enthusiasts who regularly play content with different aspect ratios.
Lens Shift
Lens shift refers to a projector's ability to adjust the lens's position and move the projected image up, down, left or right. This allows you to place the projector off-center and still project a straight, aligned image onto the screen. This avoids keystone distortion or other image distortions caused by projecting at an angle.
Letterboxing is caused by displaying a widescreen image on a screen with a different aspect ratio, resulting in black bars appearing at the top and bottom of the image. This is done so the image appears in its correct aspect ratio without being stretched or distorted. For example, suppose you watch a widescreen movie on a traditional 4:3 aspect ratio projector screen. In that case, black bars will appear at the top and bottom of the screen to maintain the original widescreen aspect ratio of the movie.


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Native Resolution
Native resolution is the maximum resolution the projector can display without scaling the image, which can affect the quality and clarity of the picture. For the best picture, use content with the same resolution as the projector's native resolution. For example, if you have a 4K projector, try to play 4K material for the best picture quality.


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Picture-in-Picture (PiP)
Picture-in-Picture is a projector feature that simultaneously displays two different images or video sources on the same screen. It is like having two separate windows or screens overlaid on top of each other, with one smaller than the other. This can be useful for presentations, gaming, or watching multiple videos at the same time.
Pixel Shift
Pixel shift is a technology used by some projectors to enhance the resolution of the projected image. It works by rapidly shifting the position of pixels in a diagonal direction by a small distance, creating a higher resolution image than the projector's native resolution. This can result in a clearer and more detailed picture.


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Refresh Rate
The refresh rate refers to how many times per second the image on the screen is updated. A higher refresh rate means the image updates more frequently, resulting in smoother motion and less flicker. A typical refresh rate for projectors is 60 Hz. However, some projectors offer higher refresh rates of 120 Hz or more, which can benefit fast-moving content such as sports, action movies and gaming.


Screen Gain
Screen gain is the amount of light reflected by a projector screen compared to a flat white surface. A higher screen gain means more light is reflected back to the viewer, resulting in a brighter and more vibrant image. This can be especially useful when ambient light is present and may otherwise wash out the projected image. However, higher screen gain may also result in more visible texture or "hot spotting" on the screen and may not be suitable for all viewing environments.
Short Throw Projector
A short throw projector can display a large image from a short distance from the screen, usually less than 4 feet away. This makes them ideal for smaller rooms or where space is limited for installing a traditional projector further away.
Standard Throw Projector
A standard throw projector needs to be placed at a certain distance from the screen to project an image properly. The distance required for a standard throw projector is typically 1.5 to 2 times the screen's width, meaning the projector would have a throw ratio of 1.5:1 or 2:1. They are suitable for larger rooms or outdoor spaces where a larger image size is required.


Throw Distance
The throw distance is the space required between the projector and the screen to display a specific image size. This distance depends on the projector type and lens used. Knowing the throw distance is essential when purchasing a projector, as it indicates the required position for achieving your desired image size.
Throw Ratio
The throw ratio is a measurement used to describe the distance between a projector and the screen relative to the projected image's width. It helps you figure out how far from the screen you need to place the projector to get a particular size image. A typical throw ratio for a standard throw projector is 2:1, meaning the image covers one foot of width for every two feet of distance between the projector and the screen.


Ultra-Short Throw Projector (UST)
An ultra-short throw projector can produce a large image from a very short distance from the screen or wall. Ultra-short throw projectors are becoming popular in home theaters because they can provide a large cinematic image even in a small room, and you don't have to run wires everywhere. The typical throw ratio for a UST projector is less than 0.4:1, although the specific throw ratio for a UST projector will vary depending on the model and manufacturer. For example, a typical UST projector with a throw ratio of 0.25:1 can project a 100-inch diagonal image from just 25 inches away from the screen.
Uniformity refers to the consistency of brightness and color across the entire projected image. A projector with good uniformity will display an even and consistent image without noticeable variations in brightness or color in different screen areas. Poor uniformity can lead to distracting "hotspots" or "cold spots" in the picture, diminishing the overall viewing experience.


Video Graphics Array (VGA) is an analog video connection standard widely used for connecting computers, monitors, and projectors. It utilizes a 15-pin connector to transmit analog video signals. While VGA has largely been replaced by digital connections such as HDMI and DisplayPort, some older equipment may still feature VGA ports.


Wireless Connectivity
Wireless connectivity is the ability of the projector to receive audio and video signals from a source device (e.g., a computer, Blu-ray player, or streaming device) without the need for physical cables. This can be achieved through Wi-Fi, Bluetooth, or proprietary wireless transmission systems like AirPlay and Chromecast. Wireless connectivity offers greater flexibility in the placement of devices and reduces cable clutter.


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Zoom is a feature that allows users to adjust the projected image size without physically moving the projector. This is typically achieved by adjusting the focal length of the projector's lens. Zoom can be manual (controlled by a dial or lever on the projector) or motorized (controlled electronically through the projector's remote or on-screen menu).
Zoom Lens
A type of lens that allows the user to adjust the image size by physically zooming in or out without having to move the projector.

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About The Author

Paul started the Home Cinema Guide to help less-experienced users get the most out of today's audio-visual technology. He has been a sound, lighting and audio-visual engineer for around 20 years. At home, he has spent more time than is probably healthy installing, configuring, testing, de-rigging, fixing, tweaking, re-installing again (and sometimes using) various pieces of hi-fi and home cinema equipment. You can find out more here.

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