Projector Vs TV, How does a projector work?

What is Lumen in a projector?

Projector lumens means the amount of light coming out through the projector lens which forms the picture on the screen. The amount of light coming out of the projector is measured with a unit of light called 'Lumen'. A 'Lumen' is a measure of how bright a source of light is. One Lumen is defined by the Standard International (SI) unit as "the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions". One lumen per square foot equals one Foot-Candle or one Lumen per square Meter equals one Lux.

Historically the measurement of light evolved from the amount of light given by a candle called CandlePower. To quote from Wikipedia "The term candlepower was originally defined in the United Kingdom, by the Metropolitan Gas Act 1860, as the light produced by a pure spermaceti candle that weighs 1/6 pound (76 grams) and burns at a rate of 120 grains per hour (7.8 grams per hour). Spermaceti is a material from the heads of sperm whales, and was once used to make high-quality candles."

From the unit of Candle-Power emerged the International unit for measurement of Light, the Candella. The old Candle-Power is equal to about 0.981 Candela.

To put it all this simply, the higher the 'LUMEN' in a projector the brighter it is. When comparing brightness of projectors, we should use the ANSI Lumen. ANSI stands for 'American National Standards Institute'. So when we use ANSI Lumens to compare different projectors, we are comparing apples to apples, and it gives as an accurate idea of how bright a projector is.

What is HDR

HDR stands for 'High Dynamic Range' in any image and refers to the difference between the darkest area of an image to the brightest area. As far as TV and projectors are concerned a set of HDR specifications have been made by different organisations to make uniform standards for the Color Dynamic Range. These HDR standards aim to improve the picture quality and to reproduce TV and projector images identical to what the producer of these images envisaged - that is to make the images we see on TV or a projector screen as close as possible with the image that was originally recorded. This is acheived by the use of metadata incorporated at the time of recording and which can be read by the display device.

Currently there are three HDR standards: HDR10 format by the Consumer Technology Association, HDR10 Plus Standards issued by Samsung and Amazon Video and Dolby Vision HDR format from Dolby Laboratories. There is also a new format of HDR called HLG HDR which is made for Broadcasters by BBC of UK and NHK of Japan to deliver HDR content over broadcasts.

The HDR Format standards specify the brightness, colour accuracy, and the dynamic color range between the darkest and brightest colors on an image to produce more life like images with vivid colors. The concept of HDR is based on 4 qualities of a digital image namely:
Luminance: How bright the image is measured in NITs or Candelas per Square Meter
Dynamic Range: which is the difference between the brightest and darkest part of an image.
Color Space or Gamut of Colors: which is the range of colors the TV or Projector can produce. The standard for Color space is REC 2020 an improved version of REC 709 / sRGB.
Bit Depth: is the amount of data required to display the brightness and color. Standard RGB colour spectrum uses 8 Bit which is equal to 2 to the power of 8 = 256 colors. HDR uses 10-Bits and produces 1024 colors.

HDR 10, HDR 10+ and Dolby Vision all use something called Perceptual Quantizer ( PQ ). To put it simply it is the way of emphasising the darker areas of an image which the Human Eyes perceives much more clearly than the brighter parts of the image.

What is the difference between HDR and Dolby Vision

The difference between HDR and Dolby Vision is that while HDR10 is a non-proprietary open standard, Dolby-Vision is a proprietary Standard which requires license from Dolby and involves the payment of fees. Dolby Vision Standards are much higher and more stringent than HDR-10 Standards.

HDR 10 is the common standard for High Dynamic Range and specifies it should have a 10 Bit Video, REC 2020 color gamut and 1000 NITs of peak brightness. Dolby Vision is a much higher standard for Dynamic color range and should have 12 Bit Video, REC 2020 color Gamut and 4000 NITs peak brightness.

As of now there are no projectors which meet the Dolby Vision Standards and only a handful of TVs certified as Dolby Vision.

What's the best lumens for a projector?

One of the most common questions regarding any projectors is ‘what is the best lumens for a projector?'. How many Lumens needed for a good home theater projector depends on several factors like how much ambient light is there, what is the screen size, what type of screen is used - ALR or high gain. Higher the ambient light the more the Lumens the projector needs. For example, the Lumens required for a projector to be used during daytime without drawing the curtains to darken the room will be high unless you have special screens like an ALR screen as explained in our page about ALR screens. Whereas the required Lumen in a home projector for use during daytime with a screen size of 100 inches in a room with controlled lighting using blackout curtains or blinds, can be as low as 1000 Lumens. You can watch movies during daytime in a semi darkened room with non blackout curtains using a 1500 Lumens projector on a screen of size 100 to 120 inches . The best way to use projectors is to have controlled lighting with the use blackout blinds or blackout curtains. It is also possible to have remote controlled blinds which are not that expensive.

Projector Lumens and screen size

As the screen size increases more lumens are required to get the same brightness in the projected picture. Too much brightness in the projected image can cause eye strain and headaches. So there is an optimum level of illumination of the projected image.

The illumination or luminous intensity or the amount of light reflected off a projector screen is measured in 'LUX', the International System of Units (SI). One LUX is equal to one Lumen per Square Metre. NITs is equal to a LUX and is the most common term used when specifying the brightness of Computer, Phone and TV screens. The American way measuring luminous intensity is the Foot-lamberts (ftL). One foot lambert is a measure of light that equals 1 circular candela per square foot or 3.426 candela per square meter. 1 Foot-lambert = 3.426 Lux or 1 Lux = 0.291886 Foot-lambert.

The recommended screen brightness for movie theaters by the Society of Motion Picture and Television Engineers (SMPTE) is 16 Foot-Lamberts. The 16 Foot-Lamberts figure is for a dark movie theater. This is a good reference figure to use for home theater screens, but it is generally accepted that home theater screens should be made brighter because of ambient light which cannot be so well controlled as in a movie theater. Generally a good screen brightness for a home theater projector screen is from 40 ftL to 80 ftL depending on the ambient light.

Where to buy Home Theater Projectors and Projector Screens online

The best place to buy Projectors and Projector screens is the Amazon online store in your country. Amazon is best to buy online Projectors and Screens because not only are they very competitively priced, but you also have the assurance of service, and in the worst case, even return for a refund in case you are not satisfied.

Links for Home Theater Projectors

This is the Link for Home Theater Projectors from Amazon AUSTRALIA

This is the Link for Home Theater Projectors from Amazon CANADA

This is the Link for Home Theater Projectors from Amazon INDIA

This is the Link for Home Theater Projectors from Amazon UK

This is the Link for Home Theater Projectors from Amazon USA

Links for Projector Screens

This is the Link for Projector Screens from Amazon AUSTRALIA

This is the Link for Projector Screens from Amazon CANADA

This is the Link for Projector Screens from Amazon India

This is the Link for Projector Screens from Amazon UK

This is the Link for Projector Screens from Amazon USA

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