Tuesday, August 20, 2013

Digital Signage Need to Know: CMYK vs RGB and Other Design Factors for Digital Content on LED Signs.

-Scott Hofheins

There is a reason why we talk about content so much on this blog. Content is the driving force behind your viewers ability to notice your sign, retain the information, and act. You want them to do this quickly and without confusion or delay. This is why investing in a content creation service who specializes in LED signs, or training your own in-house designers on outdoor content is worthwhile. The days of text only signs are going away, making way for full color advertising machines, ready to take whatever you can throw their way.

What is CMYK and why won’t it work on an outdoor LED sign? Why do some signs look great and others look blurry and hard to read? Content for print media is different in many ways than content for digital media. Additionally, content on an outdoor LED sign is different than content on an indoor Digital Sign (LCD Monitor). Knowing how to handle these differences is key to providing a dynamic readable message on an outdoor LED sign.

This is a common difference that comes up a lot when designers familiar with print media are working on digital media. The bottom line is this: CMYK is for print media, and RGB is for digital media.

  • CMYK: Stands for “Cyan (blue) Magenta (red) Yellow and Kent (black)” These are the colors of the ink that printers mix together to created printed media.
  • RGB: stands for “Red, Green, and Blue”. These are the colors of light, that mixed together can create all the different colors we see on TV Screens, HD Projectors, and of course outdoor LED signs.

Any content made for digital displays of any type is being converted to RGB in one way or another. CMYK works for print media because you are ‘coloring’ the paper with ink. This ink will reflect light to produce a certain color. However, displays are physically producing this light to create colors, so they work in terms of Red Green and Blue. When mixed together in equal values they create white light. When they are all off, they create black.

In most cases you need to physically change the ‘color pallet’ of any files you send to a digital device from CMYK to RGB. This embeds the correct color information into the file so there is a direct translation value for the colors in the file, and the corresponding Red, Green and Blue light values.

DPI Value
This is another common term used in print media. It stands for Dots Per Inch and measures the amount of data the file contains “per inch” of the printed page. This is an important value in print media because a print with 300 dots per inch is going to be higher resolution than a print with 72 dots per inch.

However, it means absolutely nothing for digital media. Digital media is being displayed directly on a display with a set number of pixels that will not change regardless of how large the display is in inches. Saving content used for digital media with a high DPI only increases the file size, not the quality of the file.
Content Pixel Resolution
Monitors are typically 1024x768 or higher. This means 1024 pixels wide by 768 pixels high. However, outdoor LED signs are much larger and viewed from a distance, so they don’t need that many pixels. They range from 16x48 pixels all the way up to digital billboards that push 200x400 pixels.

Designers who feel comfortable with web design, or print media won’t usually have a hard time with billboard content. However, most outdoor LED signs are not billboards and have a lot less space to work with. Knowing how to use this space effectively can mean the difference between a viewer saying “Wow, that’s a great deal!” or “What did that sign say? I couldn’t read it.”

Font Size and Style
Font’s take up a certain number of pixels depending on their size. Sizing these fonts correctly according to the size and pitch of the sign is important. Fonts that are too small won’t be readable, or appear blurry.

Font style is important as well. The quick readability of a font is important and there are some that are good for LED signs (thick and bold) and other that are not (fancy and thin). Knowing how to use a variety of font styles while maintaining readability is extremely important for LED sign content.

These are just a few of the factors that designers need to take into account when creating content for outdoor LED signs. There are many others including pixel pitch, road speed, color matching, viewer distance, and a host of others that must be taken into account. This is why I feel the investment in a content service or an in-house designer is worth the cost. It’s not enough to just have funny quotes and smart text on an LED display anymore. Viewers expect dynamic, colorful content that is readable and memorable. Let a pro handle it, and give yourself a little more time to focus on what you do best, operating, building and expanding your business.


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.

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