Everything You Need to Know About Projectors

The projected brightness

The projected brightness corresponds to the power of the light emitted by the projector. It is measured in lumens. The higher the number of lumens, the more powerful and, therefore, the brighter the projector is. As mentioned earlier, brightness alone is not enough. All project constraints that might reduce the projector’s theoretical power must be considered: ambient light, desired image size, and material of the surface.

In general, mapping is a technique to be used in dark spaces or at night. It is impossible to create mapping in broad daylight, even with 20,000 lumens 🙂

The light source of a projector is a key element that influences its overall performance. There are three main types of light source technologies: traditional lamps, LEDs (Light Emitting Diodes), and lasers.

Traditional lamps, often referred to as short-arc lamps, have long been the standard for projectors. They offer high brightness but generally have a shorter lifespan, typically ranging from 1,000 to 3,000 hours. They also require regular replacement, which can increase the total cost of ownership of the projector.

LEDs, on the other hand, are a newer light source technology that offers several advantages. They have a much longer lifespan, often up to 20,000 hours or more, and they consume less energy than traditional lamps. LEDs also turn on and off instantly, eliminating the need for warm-up and cool-down times. However, LED projectors typically have lower brightness than traditional lamp projectors, although this difference is becoming less significant with technological advancements.

Projectors with laser light sources are the latest technology on the market. Like LEDs, lasers have a very long lifespan, exceeding 10,000 hours, and they consume less energy than traditional lamps. Lasers also offer excellent color quality and high brightness, making them ideal for professional and high-end applications. However, they are generally more expensive than lamp or LED projectors.

Разрешение

The resolution of each projector represents its maximum pixel display capacity. The more pixels there are, the sharper the image will be. In fact, the higher the pixel count, the less distinguishable they will be to the naked eye.

The resolution should be as close as possible to that of the source. If the content you wish to project is in Full HD (1080p), opt for a projector with Full HD resolution rather than a lower resolution, such as an HD projector. Otherwise, you may be disappointed with the result.

Для получения четкого изображения, we recommend using content and a projector with at least an HD (720p) resolution.

You should also note that regardless of the resolution, projection on non-flat surfaces can make pixels appear larger and more visible. Always try to find the best placement for your video mapping projector to avoid image distortion.

For more information on image resolution, you can refer to the section dedicated to the presentation of graphic concepts.

Aspect ratio and zoom

The image size and projection distance are linked by a very simple mathematical formula: ratio = throw distance / image width.

The ‘projection ratio’ is a characteristic specific to a projector. It’s a number between 0.3 and 12. The larger this number, the greater the throw distance required. Using this formula and knowing two parameters, you can easily determine the third.

Some projectors display a range of ratios, such as 1.12:1 – 1.47:1. This means they have an optical zoom that can adjust the lens and, therefore, change the image size without altering the resolution.

Example 1: Which projector to choose for a given setup?

“I want to obtain an image that is 3 meters wide, and I have 4 meters of throw distance. I need to determine the required ratio to choose the right projector. Here: Ratio = 4 / 3 = 1.33. This means I should choose a projector with a ratio of about 1.3.”

Example 2: How to determine the possible image size with my projector and a known throw distance?

“I have 4 meters of throw distance and a projector with a ratio of 0.8. I want to determine the image size I can achieve.

Вот: 0.8 = 4 / Image Width, so Image Width = 4 / 0.8 = 5.

This means I can obtain an image that is 5 meters wide.”

Projectors can be categorized into three main types based on their lens ratio:

Ultra short throw: ratio < 0.3

Ultra short throw projectors generally have a similar appearance and are often seen in classrooms or meeting rooms. They are placed on a table, ceiling-mounted, or sometimes even attached to the same wall as the projection surface using a bracket.

Their projection ratio is low, so they need to be very close to the projected image. For this reason, they are not necessarily the first choice for projection. For example, they are not optimized for three-dimensional surfaces due to the very short throw distance.

Short throw: 0.5 < ratio < 1

Short throw projectors are ideal if you need to project images but don’t have much space around you. These models are often seen in apartments for home cinema and are typically used for recreational purposes.

This is a common scenario when you don’t have much distance from the projection surface but have relatively large areas to cover.

There is a maximum throw distance that you cannot exceed, otherwise the projected image will not be of optimal quality: it may become blurry or pixelated.

Standard and long throw: ratio > 1

Standard throw projectors simply offer a much greater distance than short and ultra short throw projectors. They provide much more distance than short throw projectors, making them optimal if you don’t have short-distance constraints.

Colors

Several main technologies are used in projectors to generate colored pixels: LCD (Liquid Crystal Display), DLP (Digital Light Processing), and LCoS (Liquid Crystal on Silicon).

LCD projectors use three liquid crystal panels that correspond to the primary colors of light: red, green, and blue. The projector’s light source, typically a lamp, emits light that passes through these panels. The liquid crystals in each panel control the amount of each color of light that passes through, thus creating the colored pixels we see on the screen.

DLP projectors use millions of micromirrors on a DLP chip. These micromirrors tilt rapidly to create an image. To produce colors, most DLP projectors use a color wheel that spins between the light source and the DLP chip. This color wheel is divided into sections of red, green, and blue, and as the light passes through each section, the DLP reflects the appropriate pixels for each color. The color wheel in DLP projectors can sometimes cause “rainbow” effects when projecting white light.

LCoS projectors combine LCD and DLP technology. They use liquid crystals on a reflective surface to modulate light. Like LCD technology, LCoS technology uses three panels for the primary colors. However, instead of light passing through the liquid crystals, it is reflected and modulated, as with DLP technology.

If you’re looking for a projector with the best brightness + image quality / price ratio, we recommend DLP technology.

Контраст

Contrast represents the difference in brightness between white and black (the absence of color). No projector can perfectly project black; it is replaced by a very dark gray.

Contrast is expressed with two numbers: ‘500:1’ (read as: 500 to 1). The greater the difference between the two numbers, the better the contrast quality of the projector. So, 1000:1 is better contrast than 500:1.

Note: Good contrast is not everything; ambient light can disrupt contrast. Thus, in a brightly lit room, the projection will be affected and appear dull, even with a contrast ratio of 20000:1.

Advanced features

• Interchangeable lenses: Some high-end projectors offer the ability to swap lenses based on the required projection distance. These projectors can also store specific settings for different lenses, making it easier to configure the projection based on the desired throw distance.
• Lens shift: The “Lens Shift” feature allows you to adjust the position of the projected image without moving the projector. This function is particularly useful for aligning the image with the screen in situations where the projector cannot be positioned directly in front of the screen.
• Edge blending and projection warping features: These functionalities allow you to correct image distortions caused by projecting onto a curved screen and to use multiple projectors to display a larger image. They are particularly useful when you need more brightness or want to project onto a large surface. Generally, we recommend performing all these adjustments directly in the video mapping software to have all settings in one tool and minimize potential issues.
• HDBaseT and 3G-SDI: These technologies enable the transmission of video signals over long distances, up to 100 meters, making them ideal for live video production. HDBaseT allows HDMI signals to be transmitted over a low-cost CAT5e/CAT6 cable, while 3G-SDI enables the projector to connect directly to a video source via a coaxial cable.
• 4K Support: Some high-end projectors can display 4K content, providing a sharper and clearer image than HD projectors that use pixel-shifting technology. To take full advantage of this, you’ll need to ensure that you’re projecting 4K content.
• Multi-laser engine: This feature enables the production of high brightness, for example 16,000 lumens, using multiple laser diodes. If one diode in a module fails, only a limited number of diodes in the series are affected and bypassed, while the remaining diodes continue to operate, maintaining brightness close to full intensity.
• Information monitor: Some high-end projectors have a small screen located at the back that aids in menu navigation and displays the projector’s status, including temperature, operating time, active signal data, and error codes.

What is EDID?

EDID ( Extended Display Identification Data) is a standard that allows a display device (such as a projector) to communicate its capabilities to a video source (such as a computer). EDID information includes supported resolutions, refresh rates, screen size, and other key details. These data enable the video source to automatically select the most appropriate settings for the display.

However, issues can sometimes arise related to EDID management by computers. For instance, a computer may not be able to correctly read a projector’s EDID data, which can lead to poor display resolution, miscalibrated colors, or even no video signal. Additionally, if a system uses multiple display devices with different capabilities, EDID management can become complex, as the computer must choose a set of parameters that works for all screens. Therefore, good EDID management is essential to ensure optimal display quality and compatibility between different devices.

The HeavyM video mapping software automatically recognizes display devices connected to the computer through EDID. What are the benefits? HeavyM allows you to:

• configure output management once: if you unplug and reconnect the projectors, the assignment will be retained and automatically restored
• turn off and restart the computer, close and reopen the software, and turn projectors off and on without losing display settings.

Positioning and mounting a projector

The correct positioning of a projector is crucial for video mapping for several reasons. First, the projection must be precisely aligned with the surfaces on which the image is mapped. Even the slightest variation in the projector’s orientation can lead to distortions in the projected image, which can detract from the desired visual effect. Additionally, image parameters such as size, resolution, and aspect ratio also depend on the distance and angle of the projector relative to the projection surface. Finally, incorrect positioning can cause issues with brightness and contrast, making the projected image difficult to see or appreciate.

To securely mount a projector, several methods are available. One of the most common is using ceiling mounts, which allow the projector to be suspended at an appropriate height and angle. These mounts are usually adjustable, enabling adjustments to the projector’s orientation if needed. For temporary installations, tripods can be used, but they require extra care to prevent accidental movement. Wall mounts are also available for situations where ceiling mounting is not possible. Regardless of the chosen mounting method, it is essential to ensure that the projector is securely fixed and not at risk of moving, even in the event of vibrations or movements in the environment.

Connecting multiple projectors

There are several methods to connect multiple projectors to a computer, each with its own advantages and disadvantages. The simplest method is to use multiple video outputs on your computer, if available. This could include HDMI, DVI, DisplayPort, or VGA ports. However, this may be limited by the number of video outputs your computer supports.

Another solution is to use a video splitter, which takes a video signal from a computer and splits it into multiple outputs to send to several projectors. However, this means the same content will be displayed on all projectors. Это solution is often not suitable for video mapping.

For more precise control over the content displayed on each projector, you can use a device that allows you to route different video sources to different projectors, such as the Matrox TripleHead or Datapath FX4.

If you’re interested in using multiple projectors in HeavyM, check out this article: Как использовать несколько проекторов в HeavyM

Purchase recommendations

If you are a beginner looking to start with video mapping, it is recommended to begin with a projector that offers a good balance between cost and performance. A projector with a 1920×1080 resolution (Full HD) is a good choice because it will allow you to project sharp and detailed images. Brightness, measured in lumens, is also a key factor to consider. A brightness of at least 3000 lumens is recommended for indoor performances, while a brightness of 5000 lumens or more may be necessary for outdoor projections.

When purchasing a used projector, there are several points to consider. First, check the condition of the projector and ask how many hours the lamp has already been used. The lifespan of a projector lamp is typically 1000 to 3000 hours, and its replacement can be expensive. Next, ensure the projector is in good working condition by testing it before purchase. Check the clarity and quality of the image, and make sure there are no dead pixels. Finally, ensure that the projector has all the necessary connection ports required for your setup.

To continue

Connections and signal transmission

This guide was written by HeavyM, a company specializing in video mapping since 2013.

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