Pixel Pitch as an Image-Quality Compound

I’ve found myself laboring to describe the visual realities of pixel pitch, because resolution, sufficient resolution, is difficult to explain, especially to a first-time buyer. The preferences are subjective, and, often, the beauty is in the eye of the beholder. Complicating this issue, new customers, usually, don’t comprehend the subject. They rudimentally imagine how they’ll use the display and how they want the image to appear, but no more.

Additionally, I’ve learned that buyers dislike fuzzy images, that is, excessive pixel pitch, but discount the relationship of pixel pitch to image resolution.

As part of a sales presentation, I recently demonstrated how different pixel pitches affect a full-color, LED-lamped display. This interesting, real-life exercise displayed differences nearly impossible to convey through words or photographs.

My customer had space limitations for the proposed, 8 x 16-ft. sign and, because cost upsurges as resolution (pixel pitch) increases, he wanted to see image-quality differences as the resolution changed. The demonstration helped him choose the lowest, acceptable image resolution for the best price.

As much as possible, our shop replicated the future sign’s features, assembled each demonstration board similarly, but with different pixel pitches between the lamps. We presented the four displays side-by-side, for simultaneous viewing from various distances. The pixel-pitch counts were 12.7, 16.5, 20 and 25mm, respectively. Table 1 displays a comparison chart for the 8 x 16-ft. display.

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I displayed six still and six animated images on the four displays and positioned my customer at different viewing distances each time, so he could study the relative resolution. Complicating his decision was the cost vs. image quality — LEDs are a display’s highest-priced component — the tighter the pitch, the greater the sign cost.

For example, a 25 x 25-ft., LED-lamped display, using 25mm pixel pitch, would present 300 lines of resolution, or 90,000 total pixels. Such a sign could cost as much as $375,000 and produce excellent images for passengers in cars passing 200 ft. in the distance. The same sign size, with a lower pixel count, may cost $200,000, or, oppositely, at 12.75mm resolution, it could run up to $1 million dollars.

Cost compounding

Most customers, unfamiliar with the cost-compounding influence of added pixels, are surprised by the exponential price change. For example, a 20mm pixel-pitch display has roughly 232 pixels/sq. ft.; 19mm has 256. The 1mm difference could amount to a 10% difference in the cost of a display. The second table (Table 2) shows the difference in my presentation’s four examples.

As you can see, resolution gains relate to cost increases, and, with larger, or multiple displays, significant money is at stake. Most important, in decisionmaking, are the viewing distance and content type. Also, allow for multiple criteria, such as viewing distance, when determining a minimum, acceptable pixel pitch.

Viewing distance affects how much detail the eye can see, so study your buyer’s content plan, and intended use, before selecting the pixel pitch. For example, a photograph of a face may reveal facial details when displayed at 20 ft., but the same image, seen from 200 ft., won’t, even if the display is adequately sized. Streamed, animated messages generally require less resolution than still, photographs.

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Text, too, is a major consideration. A display with a 25.4mm (1-in.) pitch offers only one pixel (in height) for each inch of copy. Using five lines of resolution, a display can’t adequately present 5-in.-high, stylized letters.

Cost and competitors

Once, a customer growled because my price quote doubled that of my competitor’s. I immediately knew the dissimilar figures reflected a pixel-pitch gap. One, or both of us, had wrongly surmised what the customer needed.

When your customer doesn’t understand displays, explaining cost variances becomes difficult. A customer wants the lower number, and the seller’s must justify a higher price.

Selling too low of a resolution can also devastate a customer. I’ve witnessed a customer who wanted to show photographic- or television-type images, but an inexperienced salesperson sold him a low-resolution display. Of course, the customer loved the price, but, when the sign went live, he became angry. “Tune it in,” he said, “The image is fuzzy.”

You can’t tune in an image that has insufficient resolution.

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My demonstration customer was an experienced sign buyer; his final decision regarded image quality against dollars. He knew, for example, that the price increase between a 16.5mm and 20mm pixel pitch was close to a million dollars.

To ensure his satisfaction, I decided to visually demonstrate the difference. It worked. He liked the choice options and ultimately made a comfortable decision. No one — he or our company — worried about the sign’s final appearance.

Most sales calls don’t warrant such an expensive demonstration. Still, I believe it’s important for salespeople and digital-sign designers to carefully regard their customer’s needs — and what they’re proposing — so they sell, and install, an effective and fairly priced sign.