Pixel Pitch (or dot pitch) is a term used on a daily basis in our industry. It is a core specification that will determine the clarity, effectiveness, and cost of an LED sign. Although Pixel Pitch is also used in any type of digital display (computer monitor, LCD TV, etc...) it is still not a common term for the general public and can sometimes be difficult to understand it’s role.
I’ve listed some common questions about LED signs below. You may feel like they move off the subject, but I promise it will make sense at the end.
What is Pixel Pitch?
At it’s core, it is a measurement of how close each pixel is to another on a display, typically measured in millimeters. The lower the Pixel Pitch, the more pixels you can fit together on a display.
Great...so what is a pixel?
A pixel is a single point of light on display, consisting of (3) individual colors: Red, Green and Blue. When each is lit at the same full intensity, the pixel produces white light. When they are at different intensities, shades of colors are produced.
A display contains thousands of pixels, laid out on a grid. The actual number of pixels high, and the number of pixels wide is call the “Native Resolution” of a display. The computer monitor I am using to write this post is 1600 pixels wide, by 900 pixels high, or 1600x900. An HD, LCD Television would be 1920x1080. Notice the “1080”? This is where the HD 1080p classification comes from. It designates that the display is 1080 pixels high.
What does that have to do with LED signs?
They use pixels just like LCD TVs and Monitors. However, LED signs are outdoors, large, and fighting sunlight so they must use physical Red, Green, and Blue LED’s instead of liquid crystals. Additionally, they use significantly less pixels than monitors or LCD TV’s (unless you're in Las Vegas) because they are viewed from a distance.
We call the “Native Resolution” of an LED display it’s Pixel Matrix. Typical digital billboards will have matrixes like 168x584 or 216x763, while typical commercial displays would include smaller matrixes like 32x128 or 48x96. The larger the matrix, the more information you will be able to fit on the sign.
What does the Matrix have to do with Pixel Pitch?
The more pixels you can fit into a sign (higher matrix) the higher the resolution will be, and the closer you can be to the display and still clearly see the image or text. Believe it or not you may be more familiar with Pixel Pitch than you realize. Do you know why Apple’s “Retina” displays are so crisp? Because they have been able to squeeze more pixels into the same amount of space. This is done by decreasing the Pixel Pitch. In fact, pixels are so close to each other these days that they are now measuring them in PPI (pixels per inch).
How does Pixel Pitch affect an LED sign?
The same way it affects a computer monitor, but on a larger and more noticeable scale. Pixel pitches on LED signs may include 6mm, 8mm, 10mm, 12.5mm, 16mm, 20mm, 25mm. Most commercial outdoor LED signs will stay in the 16mm - 25mm range.
16mm and lower pitches are typically used for smaller signs to fit more pixels into a smaller area and maintain a quality image. However, they can be used for larger systems where the intended viewers will be close to the sign.
The 20mm pitch is a good middle ground for many sign owners who need to have a little of both worlds. A larger sign, but with the viewers a little further away.
25mm and sometimes 32mm pitches are commonly used for digital billboards. You may see a 20mm or 16mm on smaller billboards, or where the sign is closer to the viewers.
How does “Virtual Resolution/Pixel Sharing” relate to Pixel Pitch?
The simple answer is: it doesn't really. It’s like comparing ounces to inches. They both work together in the real world, but are not directly related. However, I am a big fan of Virtual Resolution technology when done correctly. Deacon Wardlow posted a great article about it awhile back.
Virtual Resolution technology allows a sign to share the other pixels around it to smooth out lines and graphics providing a higher quality image and increased clarity at closer distances. When this is done correctly, the actual video signal size will be double the pixel matrix of the sign. For example, a 64x144 sign would use video data sized at 128x288.
This will make a 20mm sign using virtual resolution look better than a standard 20mm sign. However, a 10mm sign of the same physical size will always look better than a 20mm sign (even with Virtual Resolution). This is because a 10mm sign physically has more LED’s, they are physically closer together, and it has a higher “Native Resolution” than the same sized 20mm.
Remember, Pixel Pitch determines how many pixels you can fit onto a display. The more pixels you have, the higher resolution the display will be when viewed close up. However, larger signs viewed further away do not require a low pixel pitch. Keep in mind that Virtual Resolution technology is great, but is not directly related to pixel pitch so make sure you compare apples to apples. I hope this post has been helpful, and for those looking into buying an LED sign I encourage you to educate yourself as much as possible; I promise it’s worth the effort.
I hope this post has been informative and helpful. As usual, I welcome ALL constructive comments. Please feel free to comment and add anything I’ve missed, or additional tips you may have regarding this topic. Please visit www.vantageled.com for many other resources, white papers, and of course: Great looking LED Signs!
**All posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.