Projector contrast ratio: how it drastically impacts your projector

Last updated on December 17th, 2019 at 10:27 am

Contents

Introduction

Projector jargon is notoriously confusing. For some reason projectors seem to go out of their way to confuse new buyers. Although this is somewhat counterintuitive, fortunately we’re willing to  break it all down – starting with projector contrast ratio.

High contrast
Low contrast

Contrast ratio 

Contrast ratio is one of the few methods of terminology that doesn’t fit into that mould. When we think of contrast as consumers, we picture increased colour intensity. However, this is not the case. 

Contrast describes being strikingly different from something else. So for example, black contrasts white. The higher the contrast, the bigger the difference between these two shades. That is, the more shades of grey fall between them. This is contrast ratio. 

Put simply, contrast ratio describes the amount of grey tones that a projector is capable of showing. The first number describes how many times brighter the whitest white is compared to the darkest black (the second number shown). 

500:1 means that the whitest white is 500 times brighter than the darkest black. This means there are 498 shades of grey between the two numbers. Similarly, there are 2998 shades of grey in a contrast ratio of 3000:1. 

The more shades of grey a projector can show, the more depth an image is capable of having. If you use 3 tones to create shadow, it’s going to look more “blocked out” than using 3000 tones to show the same shadow. Because of this, higher contrast ratios show more depth within shadows.

But what does this mean?

More details within shadows will ensure your projector shows exactly what the director intended you to see. If you have a dark scene, you want to guarantee your projector shows you what’s going on. By having a higher range of shades, your projector will be able to distinguish different shapes and objects and relay that information to you. With lower contrast ratios your projector doesn’t have enough shades to relay this information.

However, contrast ratio isn’t just important across black and white, but it impacts all colours. Higher contrast ratio means there will be more shades between for example red and black or red and white. The higher the contrast ratio, the more shades your projector shows across all colours

This is not to be confused with projector resolution (pixels). Contrast solely refers to the colour capabilities of a projector. As such, you can’t use contrast ratio as a stand alone method of making a purchase decision. 

In addition to this, you need to be careful of how your projector displays contrast ratio. Contrast ratio is displayed as either:

  • ANSI contrast ratio

OR

  • Contrast ratio (on/off)

Although these may look the same, they are drastically different. When you make a purchase decision it is crucial you’re aware of this (otherwise you might be disappointed). 

ANSI contrast ratio

ANSI refers to “American National standardisation institute”. They are a non-profit organisation that seeks to standardise the measurement of different products or services. They provide a method of measuring contrast ratio that will yield consistent, valid results. 

This means that if a projector displays an ANSI contrast rating, it is an accurate depiction of the projectors true contrast ratio. Usually you’ll only see this in trustworthy brands like Epson, Optoma or LG. It’s unlikely that unfamiliar cheap chinese brands will use ANSI rating as the number might be less marketable than the number they internally calculate. 

Measuring ANSI

ANSI contrast ratio is calculated by displaying a checkerboard pattern on a projector and measuring the colour overlap at 8 points where the shades meet. At the point of measurement, there should be no diffusion of light. That is, there should be an equal amount of black to white. Often an effect called blooming happens, this is the diffusion of light in dark areas (the spreading of light). The less this light is diffused (the less white impacts the darkness of the black), the higher the calculated average contrast. 

Criticism of ANSI

However, ANSI ratio is not bulletproof. Because the measurement is taken through a reader pointed at the projection, the result can be influenced by external surroundings. It’s important to understand that an ANSI Lumen rating cannot be marketed without proper accreditation. This means that most ANSI Lumen counts are accurate and measured externally under the same conditions. 

ANSI readings differ based on:

  • Screen material
  • Ambient lighting
  • Input 
  • Colour settings of projector

On/off contrast ratio

On/off ratio is a measurement of the whitest white a projector can produce next to the blackest black. Because of this, the larger the contrast ratio, the deeper the level of black. This simply means that when your projector has a higher contrast ratio it is more capable of showcasing a bigger array of shades. 

Unlike ANSI contrast ratio, there is no predefined rules to measuring on/off contrast  – usually it is the result of one measurement as opposed to an average. This makes the number a little easier to alter into a more marketable figure. Similarly to projector Lumen count, often on/off ratio can be a little exaggerated to ensure competitiveness of product. Although not fair to consumers who have no idea of ANSI v.s. On/Off, it is completely legal to display these figures as they are a recorded measurement (we just don’t know the variables). 

That is not to say you shouldn’t trust on/off contrast figures, just be aware of how the figures can be adjusted if not displayed under ANSI.

Which contrast ratio should you look for?

Both ANSI and on/off ratio have benefits and fallbacks. Often, people describe on/off to be more accurate when discussing how well a dark scene can be depicted. However, this is without factoring in:

  • Bright scenes
  • Methods of measurement

Bright scenes 

ANSI measures how well bright scenes perform, especially when a darker object is present. This measures how well the black object stands out against its surroundings without being overpowered. 

Methods of measurement 

Unfortunately on/off contrast measurement is a lot less standardised than its ANSI counterpart. So although it is a better measurement when discussing darker scenes, there’s no way to guarantee the number you’re given is accurate. On/off contrast ratio is between 1/3 and 1/2 higher than if it was measured in ANSI.

So for example, if you were to have an on/off contrast ratio of 1200:1, this would measure at around 800:1 ANSI. The same cannot be said otherwise as the methods of calculating on/off greatly differs per company. 

What contrast ratio should you look for?

If your projector is using ANSI measurement, the minimum contrast you should look for is 1500:1. This is the absolute minimum ANSI reading we would recommend and if your budget allows, we would highly recommend bumping this minimum up to 2000:1. It’s important to note that in 4k projectors the ANSI Lumen count can go upwards of 50,000:1. A such, asking for a “higher” number as a minimum shouldn’t be difficult. In fact, we’ve made a list of the best budget projectors to help you out with this. 

On the other hand, if the projector you’re looking at has no ANSI rating and is simply on/off ratio you should look at a ratio between 4000:1 and 5000:1. 

If you enjoyed this article and want to learn more about different aspects of projectors, check out:

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