- Table of Contents
- Intro
- When It Matters
- Our Tests
- Alternative Methods
- Conclusion
- Comments
Our Picture Quality Tests
Contrast Ratio
The contrast ratio of a projector is the ratio between the illuminance of the brightest whites and the darkest blacks that a projector can produce simultaneously. Higher contrast results in a greater illuminance difference between the deepest blacks and the brightest whites, so shadow details and dark areas of the screen remain dark when bright highlights are visible. A projector with a low contrast ratio looks washed out whenever bright highlights are in the scene.
To test the contrast, we measure the average illuminance of multiple white and black squares at six different average picture levels (APL) and then calculate the ratio between the two. Illuminance is a metric to measure the amount of light (or intensity) falling on a given surface and is expressed in cd/m². This gives us a contrast value at each APL level, showing us how well the projector handles blacks as the image increasingly gets brighter.
Test results
When It Matters
Contrast is one of the most important aspects of picture quality with any display technology. Whether you're looking at a TV, projector, monitor, or even your phone, the display's contrast is usually one of the first things most people will notice. It's especially important if you're watching something in a dark room. Contrast isn't just about deep blacks or bright whites but the difference between them. If you're watching a movie in a dark room on a projector with low contrast, whites and saturated colors won't stand out well, and the entire image looks dull and flat. High contrast leads to a punchier image, with shadow details that stand out from the dark and bright highlights that stand out from the background.
It's important to note that contrast measurements on a 50% APL checkerboard pattern, which is how the industry standard ANSI contrast is measured, don't paint the full picture of the projector's performance. Many factors go into producing good picture quality from a projector, including the room setup, ambient light, and even the specific screen you're using. The content also plays a big role here, as a scene's average picture level (APL) can greatly impact the perceived contrast. This is why we now measure contrast at different APLs, as simply measuring contrast on a 50% APL checkerboard doesn't tell you how the projector will perform in lower APL scenes. The lower the APL, the higher the effective contrast ratio. This is due to light leakage within the projector's optical setup, so more light going through means more light leakage and lower contrast. It's also because the more light the projector emits, the more light is reflected from your viewing environment onto the screen, again lowering perceived contrast. Thus, by measuring contrast at different APLs, we can paint a clearer picture of how the projector performs in many scenes, from very dark to brighter ones.
Our Tests
The way we measure contrast is fairly simple. Using a checkerboard pattern of alternating full white and full black squares or circles, we measure the illuminance of each and calculate the ratio between them. We repeat this process at six different APL levels: 1%, 5%, 10%, 15%, 25%, and 50%, for 96 total measurements. This process, when done with a 50% slide, is usually called ANSI contrast. However, our pattern and test methodology differ slightly from the commonly used ANSI test methodology.
Once we've measured the black and white, we can calculate the contrast ratio. To get this number, we divide the white illuminance by the black illuminance.
Native Contrast
The native contrast test measures the ratio of the projector's white and black brightness in its most accurate, post-calibration settings, with all dynamic contrast features, like iris dimming, turned off. Since it's a ratio, there's no unit for contrast. Instead, contrast is expressed as 'X:1,' with 'X' being how many times brighter white is than black. For example, a 300:1 contrast ratio would mean that the projector emits a white that's 300 times brighter than its black. The higher the contrast ratio, the deeper the blacks, and the better the picture will look.
We set up the projector in our completely black, light-controlled room to run the test. We're using a 100" Stewart StudioTek 100 projector screen with neutral gain (1.0), with the lights turned off in the room. We connect the projector to a computer, which we then use to display the six APL checkerboard patterns. We measure the illuminance of each white and black square or circle using a Konica Minolta LS-100 Luminance Meter, which is expressed in lux, and record it. We take multiple measurements to ensure our results are consistent and not impacted by stray reflected light.
KODAK LUMA 150 - 69:1 (50% APL, 0.8 Test Bench)
Optoma UHD35 - 260:1 (50% APL, 0.8 Test Bench)Looking at the two examples above from our 0.8 test bench, you can clearly see the difference between a projector with low contrast (left) and one with high contrast (right). Combined with the low peak brightness of the KODAK LUMA 150, the overall picture quality is disappointing, and bright highlights don't stand out at all. White doesn't even really look white. The Optoma UHD35, on the other hand, has bright, punchy whites, and the colors are sharp and stand out immediately, even in scenes with lots of dark elements.
To arrive at a final contrast measurement, we take the average of the white squares and divide it by the average of the black squares. We also take a picture of the checkboard pattern on the screen and overlay our measurements on the image to give you a sense of the black-and-white illuminance uniformity across the screen.
Alternative Methods
You'll likely notice that our measured contrast rarely matches manufacturer claims. Why is that? Well, there are multiple ways to measure contrast, and those sneaky manufacturers often choose the method that delivers the highest numbers for their marketing. Not all manufacturers do this, but most do. So what other ways are there? When you see numbers like 1,500,000:1, the manufacturer most likely uses a full white and full black square to measure contrast. The problem with this method is that it simply doesn't match any real-world content. The checkboard pattern above doesn't really match real content, but it's a much more complicated pattern for any display technology, so it more closely matches your real-world experience.
ANSI Contrast
Measuring contrast with a 50% APL slide is commonly called "ANSI Contrast." Before the test bench, we also measured contrast solely with a 50% APL slide, but our methodology wasn't quite in line with the ANSI standards, so we called it Native Contrast instead. Contrast measurements are extremely sensitive to stray light measurements. As our Projector Launch article explained, during our initial test development process, we discovered that even our clothing can significantly impact our measurements! Although we've taken steps to reduce reflections and stray light, our test setup with a 50% APL slide isn't good enough to be considered equivalent to ANSI contrast. Our test room resembles a typical dark-room projector setup you might have at home, but it's not as good as a true laboratory setup. This means our results with a 50% APL slide will almost always be worse than true ANSI contrast measurements.
FOFO
Another common method to measure contrast is known as FOFO, or Full-On, Full-Off. As the name suggests, this method to measure contrast uses a full white screen followed by a full black screen. This way of measuring contrast is one of the most misleading, as it's usually a lot easier for a projector (or any display) to show a full white screen or a full black screen. This rarely resembles anything remotely close to real content, so it's extremely misleading and not worth considering. Many projectors can do really well with this test yet have poor real-world contrast.
Dynamic Contrast
Many projectors include features that help improve contrast by adjusting the light output from the projector. For example, some projectors can adjust the iris when displaying a dark scene, reducing the amount of light they send. When measuring FOFO contrast in particular, these features can significantly improve the measured contrast, as they can effectively close the iris entirely when displaying a full dark screen. Brands often use dynamic contrast when marketing their projectors, as this method frequently yields the highest contrast measurements of any methodology. The problem with this method is that it rarely comes anywhere near the actual contrast capabilities of the projector, so it doesn't represent what you'll see when watching real content.
Conclusion
Contrast is one of the most important, most noticeable aspects of the overall picture quality of a projector. The higher the contrast, the better, as bright highlights will stand out better from darker areas of the scene. Although there are multiple ways to test for contrast, we use a checkerboard pattern and measure the difference in the average illuminance between the white and black squares.
Recommended Articles
Comments
Our Picture Quality Tests: Contrast Ratio: Main Discussion
What do you think of our article? Let us know below.
Want to learn more? Check out our complete list of articles and tests on the R&D page.
- 21010
Thanks for the reply! Regarding ANSI - sorry, terminology mishap there. You are not strictly measuring ANSI as in the spec but you are measuring 50% ADL which is what ANSI measures as well. My comments regarding the room/screen combo having a pretty big impact on the results stands. I really have to disagree with your decision to measure off the screen and the purpose of that being to mimic “optimized theater environments.” As I mentioned in the previous post there are multiple ways to optimize your setup further without much work. Using an ALR or grey screen would impact your ADL measurements and many readers will be buying those screens. All of your UST measurements will be understating the performance if used with a lenticular or especially fresnel screen. I’d expect Rtings to set up a lab-type of environment and not be victim to the impacts of the environment. Even just measuring off the lens would remove a lot of the environment. There’s just no way to know if your room is a good match to your readers. It could be better, it could be worse. The way your room reflects light could be different for a UST than a long throw based on how each type disperses light into the room. The reason we as reviewers typically want to measure in the most optimal conditions is that is how you level the playing field and tell the reader what is absolutely possible. If a reader has a near perfect room with black velvet then your 50% ADL measurements make it seem like there is very little difference between many projectors - which is just not true. Back to the lap-type of environment. It’s not hard to set this up, you can do it in a couple different ways. Either use a velvet lined tube or a velvet tent. The tent may be the easiest for alignment with various types of projectors and could be made out of PVC and triple black velvet from a hobby store. You could also just get velvet for your whole room. Or, getting a velvet cover for the screen that can drop down would substantially cut down on light pollution in the room and get you near ideal measurements. FOFO contrast - if you measured FOFO on a projector that doesn’t automatically dim for a full black field with and without a pixel in the corner(s) you’d find the measured contrast would be either identical or within a few tenths of a percent of each other. FOFO with a few pixels is FOFO. If you don’t want to call it FOFO then call it “0% ADL - 1px”. Doing this will speak to the performance of under 1% ADL. What I believe would be awesome for you guys to do is to instruct readers on how a projector’s contrast is influenced by the environment and screen. Projection Dream did this in a fantastic study but it is only known to enthusiasts in the community. You guys have a platform to show what a projector’s ideal contrast is, how it performs in a living room, with a grey screen, and ALR screen, a lenticular screen etc etc (for those projectors that work with such screens, of course). Projection Dream documented this with ADL graphs showing the impacts of the environment. If you made a video and an article educating the readers then they could make much more informed decisions. If they have a white living room they could see how a white screen would essentially make ADL contrast differences null. If they had a perfect black velvet room they could see the inverse. There’s no one better than you guys to take a scientific approach to this and really help members of the community understand the relationship of room vs projector vs screen. https://projectiondream.com/en/contrast-projector-environment/
Hi RtingsUser1708119,
While our current projector test bench is limited in scope, we are looking to expand it and improve our tests going forward, so we really appreciate you taking the time to share all your thoughts and insights with us about how we could improve our testing environment and contrast tests.
It’s given us a lot to consider going forward, and while we can make any guarantees of a timeline or scope of changes to our current projector test bench, we’ll be keeping all of this in mind when we get back to working on our projector test bench.
Cheers!
- 21010
Hi RtingsUser1708119, Thanks for taking the time to reach out with your feedback! We’re happy to discuss our contrast testing philosophy & methodology. Before diving into the matter, it’s important to press that we do not measure ANSI contrast, which must be carried out in a laboratory with specialized equipment to obtain the values stated by manufacturers. While we could have developed a methodology for this, we chose the route of measuring contrast directly off-screen as this is what is experienced by people at home, as light inevitably makes it way back onto dark areas of the projector screen due to reflections within the viewing environment. While it’s true that our results differ from the ANSI contrast values stated by manufacturers due to real-world environmental influences, we believe this provides a more practical representation of what users can expect in optimized home theater setups. Our contrast testing patterns were made specifically to simulate a checkerboard at various APLs and to work seamlessly with the 1° measuring angle of our Konica-Minolta LS-100 luminance meter used to carry out contrast measurements. We confirm that the Epson 5050UB held its white luminance as expected throughout all APL test patterns, with an average variation of ~2% between peak all the white measurements at the same location, which falls within the accuracy & repeatability specifications of the LS-100. The differences in measured contrast values between reviewers can be due to differences in testing environments, methodologies, instrumentation and projector settings. Our measurements are done in our recommended SDR settings, post-calibration. Regarding FOFO contrast, it is defined as the ratio between a completely white image and a completely black image, without any other elements present. Adding individual pixels would no longer fit the definition of FOFO, but instead measure very low APL contrast, well below our current minimum value of 1%, and you’re absolutely correct about many scenes being below 1% ADL. Unfortunately, we needed to limit the scope of tested APL values due to testing resources on our end. The good news is that Contrast Ratios below 1% APL will always be greater than the values we measure at 1% APL. I’ve added a note to revisit the idea of extending our testing to include ADL values below 1%. We understand that this range provides valuable information about the performance of projectors in dark scenes, and we’ll evaluate how to incorporate this in future updates to our test methodology. Thanks again for reaching out, and feel free to share any other suggestions or questions you have. Cheers!
Thanks for the reply!
Regarding ANSI - sorry, terminology mishap there. You are not strictly measuring ANSI as in the spec but you are measuring 50% ADL which is what ANSI measures as well. My comments regarding the room/screen combo having a pretty big impact on the results stands.
I really have to disagree with your decision to measure off the screen and the purpose of that being to mimic “optimized theater environments.” As I mentioned in the previous post there are multiple ways to optimize your setup further without much work. Using an ALR or grey screen would impact your ADL measurements and many readers will be buying those screens. All of your UST measurements will be understating the performance if used with a lenticular or especially fresnel screen.
I’d expect Rtings to set up a lab-type of environment and not be victim to the impacts of the environment. Even just measuring off the lens would remove a lot of the environment. There’s just no way to know if your room is a good match to your readers. It could be better, it could be worse. The way your room reflects light could be different for a UST than a long throw based on how each type disperses light into the room. The reason we as reviewers typically want to measure in the most optimal conditions is that is how you level the playing field and tell the reader what is absolutely possible. If a reader has a near perfect room with black velvet then your 50% ADL measurements make it seem like there is very little difference between many projectors - which is just not true.
Back to the lap-type of environment. It’s not hard to set this up, you can do it in a couple different ways. Either use a velvet lined tube or a velvet tent. The tent may be the easiest for alignment with various types of projectors and could be made out of PVC and triple black velvet from a hobby store. You could also just get velvet for your whole room. Or, getting a velvet cover for the screen that can drop down would substantially cut down on light pollution in the room and get you near ideal measurements.
FOFO contrast - if you measured FOFO on a projector that doesn’t automatically dim for a full black field with and without a pixel in the corner(s) you’d find the measured contrast would be either identical or within a few tenths of a percent of each other. FOFO with a few pixels is FOFO. If you don’t want to call it FOFO then call it “0% ADL - 1px”. Doing this will speak to the performance of under 1% ADL.
What I believe would be awesome for you guys to do is to instruct readers on how a projector’s contrast is influenced by the environment and screen. Projection Dream did this in a fantastic study but it is only known to enthusiasts in the community. You guys have a platform to show what a projector’s ideal contrast is, how it performs in a living room, with a grey screen, and ALR screen, a lenticular screen etc etc (for those projectors that work with such screens, of course). Projection Dream documented this with ADL graphs showing the impacts of the environment. If you made a video and an article educating the readers then they could make much more informed decisions. If they have a white living room they could see how a white screen would essentially make ADL contrast differences null. If they had a perfect black velvet room they could see the inverse.
There’s no one better than you guys to take a scientific approach to this and really help members of the community understand the relationship of room vs projector vs screen.
https://projectiondream.com/en/contrast-projector-environment/
- 21010
The way you guys measure contrast, off the screen in a black painted room, is substantially impacting the usefulness of your results. The easiest way to see how poor your results are is by looking at the ANSI contrast measurements. The highest you have yet to measure is 164:1. This is not a reflection of the projector you have reviewed but the way your room handles light. Your room has a ceiling for ANSI and you will never measure a projector’s true potential in that room. You could put a 1000:1 ANSI Barco or Christie in there and it will most likely be capped at 200-250:1. If your readers choose to use an ALR screen, or treat their room better than you they will not realize that they are capable of getting more performance from going with a higher ANSI projector. If a 500:1 ANSI projector measures at 160:1 and a 250:1 ANSI projector measures at 135:1 will they conclude that they could see double the performance in a properly treated room? (that’s rhetorical). I also wonder why you have devised your own ADL patterns and measure them differently than much of the industry. Projection Dream made huge strides in figuring out the usefulness of these patterns and created ADL patterns that operate differently than yours, creating a solid white area in the center of the screen and then dispersing that percentage of white throughout the frame when measuring black. This pattern makes it ideal for measuring off of the lens through a velvet tube - the gold standard way for measuring a projector’s raw performances and removing the unique environment in the room. I wonder if your methods are actually reflected in real world performance delta’s. The Epson 5050 you measured came in at 1780:1 at 1% which is nearly half of what others, including myself, have measured. Yet a Nexigo and Formovie are around 2500:1. These USTs are in the 3000:1 to 3500:1 native range while the Epson 5050 is usually in the 4000:1 to 5000:1 native range. This means one of two things, you got a really bad Epson 5050 to review or your patterns result in the Epson 5050 not being able to hold peak white in those small circles for some reason. Does that bear out in a 1% ADL real world image? 1780:1 vs 2500:1 should be noticeable when side by side. I’d be curious to hear if you see those differences post a good gamma calibration in a real world image. Furthermore, your comments about native or FOFO contrast are inaccurate. Projection Dream did an analysis of 50 movies of a variety of content and found that 12% of frames are below 1% ADL at 2.2 gamma. This number will increase at 2.4 gamma. Since you only measure down to 1% ADL, you do not speak to this content. Also, it is very easy to counteract the “undefeatable” dimming on some projectors. All you have to do is put 1 or 4 individual pixels in the corners of the frame and you can measure FOFO. I’d advise measuring off the lens though or with high contrast projectors you may have a bad time measuring off the screen. This FOFO number charted down through 1% ADL will tell you how a projector will handle starfields, basement scenes, night scenes, etc ect. There’s PLENTY of examples of scenes in the 0.5% range https://projectiondream.com/en/movie-brightness-adl-contrast-measurements/ FWIW, I’m not a nobody. I also review projectors and perform ADL measurements while doing so. I help put on a projector comparison every year and have extensive experience with projectors, screens, and the way they interact with each other and the environment.
Hi RtingsUser1708119,
Thanks for taking the time to reach out with your feedback! We’re happy to discuss our contrast testing philosophy & methodology.
Before diving into the matter, it’s important to press that we do not measure ANSI contrast, which must be carried out in a laboratory with specialized equipment to obtain the values stated by manufacturers.
While we could have developed a methodology for this, we chose the route of measuring contrast directly off-screen as this is what is experienced by people at home, as light inevitably makes it way back onto dark areas of the projector screen due to reflections within the viewing environment. While it’s true that our results differ from the ANSI contrast values stated by manufacturers due to real-world environmental influences, we believe this provides a more practical representation of what users can expect in optimized home theater setups.
Our contrast testing patterns were made specifically to simulate a checkerboard at various APLs and to work seamlessly with the 1° measuring angle of our Konica-Minolta LS-100 luminance meter used to carry out contrast measurements. We confirm that the Epson 5050UB held its white luminance as expected throughout all APL test patterns, with an average variation of ~2% between peak all the white measurements at the same location, which falls within the accuracy & repeatability specifications of the LS-100. The differences in measured contrast values between reviewers can be due to differences in testing environments, methodologies, instrumentation and projector settings. Our measurements are done in our recommended SDR settings, post-calibration.
Regarding FOFO contrast, it is defined as the ratio between a completely white image and a completely black image, without any other elements present. Adding individual pixels would no longer fit the definition of FOFO, but instead measure very low APL contrast, well below our current minimum value of 1%, and you’re absolutely correct about many scenes being below 1% ADL. Unfortunately, we needed to limit the scope of tested APL values due to testing resources on our end. The good news is that Contrast Ratios below 1% APL will always be greater than the values we measure at 1% APL.
I’ve added a note to revisit the idea of extending our testing to include ADL values below 1%. We understand that this range provides valuable information about the performance of projectors in dark scenes, and we’ll evaluate how to incorporate this in future updates to our test methodology.
Thanks again for reaching out, and feel free to share any other suggestions or questions you have.
Cheers!
- 21010
The way you guys measure contrast, off the screen in a black painted room, is substantially impacting the usefulness of your results.
The easiest way to see how poor your results are is by looking at the ANSI contrast measurements. The highest you have yet to measure is 164:1. This is not a reflection of the projector you have reviewed but the way your room handles light. Your room has a ceiling for ANSI and you will never measure a projector’s true potential in that room. You could put a 1000:1 ANSI Barco or Christie in there and it will most likely be capped at 200-250:1.
If your readers choose to use an ALR screen, or treat their room better than you they will not realize that they are capable of getting more performance from going with a higher ANSI projector. If a 500:1 ANSI projector measures at 160:1 and a 250:1 ANSI projector measures at 135:1 will they conclude that they could see double the performance in a properly treated room? (that’s rhetorical).
I also wonder why you have devised your own ADL patterns and measure them differently than much of the industry. Projection Dream made huge strides in figuring out the usefulness of these patterns and created ADL patterns that operate differently than yours, creating a solid white area in the center of the screen and then dispersing that percentage of white throughout the frame when measuring black. This pattern makes it ideal for measuring off of the lens through a velvet tube - the gold standard way for measuring a projector’s raw performances and removing the unique environment in the room.
I wonder if your methods are actually reflected in real world performance delta’s. The Epson 5050 you measured came in at 1780:1 at 1% which is nearly half of what others, including myself, have measured. Yet a Nexigo and Formovie are around 2500:1. These USTs are in the 3000:1 to 3500:1 native range while the Epson 5050 is usually in the 4000:1 to 5000:1 native range. This means one of two things, you got a really bad Epson 5050 to review or your patterns result in the Epson 5050 not being able to hold peak white in those small circles for some reason. Does that bear out in a 1% ADL real world image? 1780:1 vs 2500:1 should be noticeable when side by side. I’d be curious to hear if you see those differences post a good gamma calibration in a real world image.
Furthermore, your comments about native or FOFO contrast are inaccurate. Projection Dream did an analysis of 50 movies of a variety of content and found that 12% of frames are below 1% ADL at 2.2 gamma. This number will increase at 2.4 gamma. Since you only measure down to 1% ADL, you do not speak to this content. Also, it is very easy to counteract the “undefeatable” dimming on some projectors. All you have to do is put 1 or 4 individual pixels in the corners of the frame and you can measure FOFO. I’d advise measuring off the lens though or with high contrast projectors you may have a bad time measuring off the screen. This FOFO number charted down through 1% ADL will tell you how a projector will handle starfields, basement scenes, night scenes, etc ect. There’s PLENTY of examples of scenes in the 0.5% range https://projectiondream.com/en/movie-brightness-adl-contrast-measurements/
FWIW, I’m not a nobody. I also review projectors and perform ADL measurements while doing so. I help put on a projector comparison every year and have extensive experience with projectors, screens, and the way they interact with each other and the environment.
- 21010
Thanks for continually improving your testing methods.
Low APL contrast is so important for projector viewing in a dark room. The 1% APL method is much more effective than just a simple FOFO measurement due to manufacturers trickery with laser dimming etc.