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    Pixel Pitch and Viewing Distance

    If you are looking for a new LED video wall, chances are that you are being overwhelmed with technical jargon and marketing superlatives claiming the finest pixel pitches and the highest resolutions.

    But what is a pixel pitch, why isn't the smallest pixel pitch always best and how is choosing the right pixel pitch important for the success of your display?

    What is pixel pitch?

    First, let us dive into the basics: how is an LED wall actually built? An LED wall is put together out of LED tiles, which in their turn consist of multiple LED modules.

    These LED modules contain LED clusters or LED packages, i.e. red, blue and green light emitting diodes (LEDs) grouped in pixels. 

    Pixel pitch (sometimes referred to as 'dot pitch') is a technical specification that is used to differentiate between LED tiles. Note that the pixel pitch specification can also be used for other display technologies like LCD, but in this post we’re only talking LED. The pixel pitch is the center-to-center distance between two pixels, usually measured in millimeters. If you have a 10mm pixel pitch, it means that the distance from the center of one pixel to the center of the adjacent pixel is 10 millimeters.

    This results in low resolution and a grainier image quality. Tiles with lower pixel pitches have a smaller distance between two different LED clusters. That is less empty space and, thus, more pixels available on the LED module. This increased pixel density leads to high resolutions and more detailed content.

    What is the best pixel pitch?

    Let's be clear on this: there is no such thing as the best pixel pitch! You could think that the decision is easy by just going for the display with the finest pixel pitch and the best resolution, but it is not as simple as that.

    Different applications ask for different pixel pitches. If you want to know what pixel pitch to choose for your project, here are three important parameters to keep in mind.

     

    #1 Pixel pitch and optimal viewing distance

    For starters, it is key to find the optimal viewing distance (OVD) for your videowall. When looking closely at an LED module you can see the different pixels as clearly defined blocks. Taking a step back, the outlines of these blocks will start to blur and scatter.
    The OVD of your display is the distance from which you can no longer distinguish the individual pixels but start to see a uniform reproduction of the content instead. Small pitches allow for the optimal viewing distance to be shorter. The smaller the pixel pitch, the closer the LED clusters are positioned on the module and the sooner the outlines of the blocks will start to blur.

    In a living room, for instance, where viewers sit closer to the LED screen, you might want to opt for a fine pitch LED display with a pixel pitch well below 1.5mm. Large pixel pitches, on the other hand, are perfect for long distance viewing experiences like a large home cinema. The animation below shows the recommended distance for the most used pixel pitch options.

    Now if you know where your spectators will most likely be positioned in relation to the LED display, you can use the following rule of thumb to define the ideal pixel pitch your project needs:

    OVD(in m)=2 * commercial pixel pitch(in mm)

    Your ideal pixel pitch (in mm) is OVD (in m) / 2

     This is a really handy rule of thumb that applies to most cases, but critical applications might need an on-site evaluation to be 100% sure. For example, if you are using your home cinema or living room screen as a home office, or as a screening room, the OVD can increase.

    #2 Size matters

    Let’s say you’re looking for an LED solution to bring 4K brand content to life in your cinema. 4K refers to a display resolution of 3.840 x 2.160 pixels, and has become the standard for most TV's . An LED display module with a 0.9 mm pitch has a higher pixel density, it can fit more pixels than for example a 1.5mm LED module on the same physical size. Hence, it has more pixels per module available to realize the 4K content. As a result, you’ll need less modules to create a 4K display. The fine pixel pitch thus reduces the screen size and keeps the physical space requirements to a minimum.

    #3 Money, money, money

    Pricing is a 3rd factor that should not be overlooked. The total production cost of the final LED product relates exponentially to the LED density: a fine pixel pitch has more tiny LED pixels on the module. So, more diodes, more wiring and an increased manufacturing process. It all results in a higher production cost, and ultimately an overall higher purchase cost for you as a customer. In addition, more pixels also potentially entail more maintenance. In other words, if viewers don't sit too close to the LED wall, you can opt for a lower pixel pitch.

    Conclusion

    In conclusion, the ideal solution will always combine application objectives and budgetary considerations.

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    • Always take into consideration the viewing distance of your audience. Short distances ask for fine pixel pitches; whereas higher pitches are perfect for long viewing distances.
    • Think about the required content resolution, but also about the available space as the pixel pitch defines the number of tiles you need to construct a 4K or a 5K native resolution video wall.
    • Choosing a pixel density that’s too high for your specific set-up will not bring any visual advantage, and just needlessly increase the cost of your display and decrease the size of the overall screen ( if you maintain the resolution to be 4K or 5K).

    Armed with this knowledge, you can now select your optimal LED video wall solution. Don’t hesitate to get in touch with your Barco expert to discuss the best option for your specific LED project.