How to Improve a Projector's Image Quality

Written by Jonah Matthes
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Projectors can be a little finicky when it comes to the first-time setup. When you’re trying to dial the image into your screen and your unique home theater setup, it can be confusing because of the sheer number of variables in play. However, by proceeding methodically and changing 1 thing at a time, you can dial in your projector’s image by doing the following:

  1. Adjust the projector focus
  2. Check the lens for dust or condensation
  3. Change the positioning of the projector relative to the screen
  4. Adjust the keystone correction
  5. Change the sharpness and/or resolution

These are all straightforward, well-understood ways to improve projector image quality, but, if this is your first time they won’t always come naturally.

It’s OK to not automatically know what some of these words mean or how to play with some of these settings. In fact, those details you need to know are exactly what the rest of this article is all about.

Adjust the Projector’s Focus

Projector Focus

What is Focus?

There’s a reason we’re starting with focus: this is the best built-in way to adjust your projector’s image quality, especially if the problem you’re seeing is that the image is blurry or fuzzy.

Your projector will have a physical focus adjustment ring around the lens, and twisting this ring adjusts the focus by increasing and decreasing the distances between components in the lens itself.

This shift in distance either narrows or expands the image coming out of the lens. And most problems with fuzziness are simply small mismatches between where the image is in focus vs. where the screen is.

If you put your hand directly in front of the projector, it will project a small rectangle not much larger than a postage stamp. In most instances, people like to project at least a 100-inch diagonal image on a projector screen. So, something really obvious is happening here: the further you get away from the projector, the larger the image is getting.

The reason I bring this up is that it helps to understand focus if you realize that if you were to move the screen and “check” whether the image looks good from various distances in front of the projector, you will always find some distance at which the image looks good. That slice of the light beam from the projector where the image has been expanded just enough that it looks good always exists.

Adjusting Projector Focus

However, we don’t have the luxury of setting up a projector, turning it on, and moving the screen closer and further away to find that slice where the image from the light beam looks good. Instead, we use focus to allow ourselves an easy install.

You start with where you want the screen, then put the projector far enough back that it will work based on its throw ratio. When you first turn the projector on is when you use the focus ring to move that slice of the light beam where the image looks good back and forth.

Remember, that slice always exists, our job with the projector focus knob is to move it so that the slice exists on the screen. If you're still pre-install, we have an article discussing the throw ratio and some calculations you can do to get it right.

Check the Lens for Dust or Condensation

moldy and dust on dirty lens Camera image closeup.

Maybe it’s not your entire image that’s blurry or fuzzy, just a small part of it. If part of the image you’re seeing is in focus and looks correct, but other parts of the image are blurry, or if the entire image is too blurry/fuzzy to even allow you to dial in the focus, then this could be an issue with the lens of the projector itself.

That’s where the light comes from, after all, so if there are greasy fingerprints that have collected dust here, that will interfere with the light beam and lead to distortion. Different things can cause this type of issue. The most common being fingerprints, which leads to dust collecting on the lens as mentioned above.

However, for a projector that has just been sitting there for a while, dust may have found its way onto the lens over time without the help of fingerprints. If the projector has ever been disassembled, dust could actually be inside the lens causing the problem, but that’s much rarer.

Condensation

One strange issue you might have if you store your projector in a garage or attic, for instance, is that any big swings in temperature may even cause condensation to form within the lens. If that happens, though, you just have to wait for the projector to come back to room temperature naturally.

When in doubt, it's best to clean the lens off. Don't just use any piece of cloth to clean the lens, you can seriously damage it--follow our step-by-step guide to cleaning a projector lens

Change the Positioning of the Projector Relative to the Screen

How Do you Center a Projector on the Screen - Smaller

Assuming you’ve already tried to use the built-in focus knob to fix the image, and you’ve checked the projector lens for dust, fingerprints, etc., it’s now time to start considering the projector placement.

The focus knob is designed to fix issues in which the projector image is just a few inches out of sync with the distance to the screen, but if the projector is off much more than that on placement, then it’s time to consider moving it.

I’ll assume that you have the correct position from left to right for your projector--there is only 1 center-line from the screen to mount along, so it’s hard to get that wrong--but the distance from the screen is another story. That said, if you haven't installed the projector yet, here are some reasons it's important to find that centerline.

Your projector will have a requirement for the distance from the screen. Or rather, the range of distances it’s designed to project at. If you can’t fix blurriness or fuzziness in the image by the methods above, then it’s time to physically move the projector back and forth until you find the right distance from the screen. To help out here, we have a calculator you can use for that.

Adjust the Keystone Correction

How to Adjust the Image on a Projector - KeyStone Before
This is the projector's image before adjusting the keystone options.
How to Adjust the Image on a Projector - KeyStone After
This is the projector's image after adjusting the keystone options.

After getting the image focused via any of the methods above, there’s another category of changes you might need to make to improve the projector’s image quality: changes to the image-processing side of the light being projected.

The most common of these is the keystone correction, which is a feature all projectors have to fix problems of the projector’s height or center-line mounting not matching with the screen.

The two flavors of keystone correction are vertical and horizontal. So start by determining which one you most likely need to play with. As discussed above, it’s hard to mess up mounting the projector on a center-line with the screen, but maybe you have a smoke detector or some other ceiling feature blocking the right center-line spot.

If the projector is mounted off-center from the screen, the image will be skewed such that one half is bigger than the other. Horizontal keystone correction fixes this by manipulating the image before it's projected.

Vertical keystone correction does the same thing, but to address problems caused by the projector’s height. Whether the projector is mounted above or below the screen, vertical keystone correction can be used to adjust the image to fit the screen even though the projector is projected from an unexpected angle.

You can set the keystone correction by finding the keystone or keystone correction setting in the projector’s menu, and then simply dialing it in by increasing and decreasing the correction factor until the image looks correct.

And if you haven't even purchased a projector yet, be sure to buy one like the Epson Home Cinema 3700 (on Amazon) or Optoma EH504WiFi Full HD Wireless DLP Projector (also on Amazon), which both have a lot of options for both horizontal and vertical keystone correction.

Change the Sharpness and/or Resolution

Lastly, there are a few more features you can play with to dial in the image when all of the above have already been checked or worked on.

Sharpness

Sharpness, which is a term describing the clarity and contrast of an image, is usually a setting you can adjust in the menus.

You can use it to try and address issues with the image looking too washed out, or too vibrant. If the colors of a scene look “off” to you, then adjusting the sharpness can also help get that under control.

Resolution

Your projector will be designed to project at a certain resolution, but if you’re sending video through HDMI from a computer, you need to make sure the computer knows what size the image should be.

By going into your computer's display management settings, you can confirm that the computer understands what the target resolution is, and change it if the wrong value is there.

Most other devices will automatically output the highest resolution possible to the display device (in our case, a projector).

Conclusion

By now, you probably have some better ideas about how you can go about correcting your projector image. Stay at it, and remember there’s a lot of variables you might need to adjust, and then re-adjust later after you’ve changed other settings.

Through a little trial and error, though, you can dial your projector in and with any luck, you’ll never have to adjust it again.

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About Me

Hi! I’m Jonah. I grew up addicted to different electronics. I began working for an Audio/Video installation company years ago and realized my passion for Home Theaters! The Home Theater DIY is a place for me to share my different findings and experiences about home theaters and home electronics. For more information, check out my about me page!

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