How many pixels is that?

In our digital world, images are everywhere. From the breathtaking photos on your Instagram feed to the graphics on your favorite website, images play a pivotal role in capturing our attention and conveying information. However, behind every stunning image, there lies a realm of technical intricacies that can make or break the visual experience.

In this blog post, we’ll delve into digital images, exploring the critical importance of image specifications, what happens when they’re ignored, and why every pixel matters. Whether you’re a graphic designer, a digital artist, a photographer, or simply someone interested in understanding the DNA of a digital image, this exploration will shed light on the complexities of working with visuals in the digital age.

Resolution (DPI) VS. Pixels

Resolution (DPI) and pixel dimensions are two distinct aspects of digital images. Resolution refers to the number of dots (pixels) per inch in a printed image, whereas pixel dimensions represent the actual number of pixels in the image’s width and height.

For screens, such as LED displays, resolution (DPI) doesn’t matter. What truly counts is the pixel dimensions. This is because screens display images based on the number of pixels they can physically show, and they don’t have a concept of inches or DPI. So, you could have a 100×100-pixel image, and it would look the same on the screen whether it’s 72 DPI or 300 DPI because the screen will still show those 100×100 pixels. The DPI value only becomes significant when you’re preparing an image for printing, where it affects the physical size and quality of the print.

Here is an Example

Imagine this: you’re collaborating with a designer on a project that involves an LED screen display, and they casually request you send 300 DPI images with no specific pixel dimensions and no maximum file size.  This seemingly straightforward request hides a minefield of potential issues.

  1. Undefined Image Size: Sending images with no specified pixel height or width can result in unpredictable and unmanageable display quality. Your designer won’t know how to fit the images onto the LED screen properly, which could lead to distorted or cropped images.
  2. No Maximum File Size: Without specifying a maximum file size, there’s a risk of sending excessively large files that may not even be deliverable via email due to size limitations. It could also lead to a storage problem for the designer.
  3. 300 DPI: While 300 DPI is a standard resolution for print, it’s not necessarily relevant for LED screens. LED displays work on a pixel basis, and specifying DPI in this context is somewhat misleading.

A few potential outcomes of this request:

Inefficient Workflow: This request could lead to a back-and-forth communication process as the designer tries to figure out the appropriate dimensions, resolution, and file sizes for the LED screen, delaying the project.

Suboptimal Display: The designer might make assumptions and use arbitrary settings, resulting in images that don’t look good on the LED screen.


For more details take my course Understanding Image Processing for the Web CLICK HERE FOR MORE INFORMATION

300DPI 150x150pixel

Above is a 300 DPI image but since the pixel size was not requested I randomly exported the image at 150 pixels square. How does it look on your screen?

600x600pixels at 50dpi

Above is a 50 DPI image at 600 pixels square. You can see why pixels matter for screens and DPI does not. The reverse is true for print because printers export in pixels so both DPI and pixel dimension matter in print

How to Fix it

Have a clear discussion with the designer about the specific requirements of the LED screen, such as its dimensions and native resolution. You should also establish a reasonable file size limit for email transfers or consider alternative methods for file sharing, like using a file-sharing service or FTP.

Clarity and effective communication are essential to ensure a successful LED screen display project.

Here are some typical screen sizes for various devices

  • Flip Phone Display: 240×320 pixels
  • Smartphone (iPhone SE): 640×1136 pixels
  • Tablet (iPad Air): 1668×2388 pixels
  • Laptop (13″ MacBook Air): 2560×1600 pixels
  • Full HD TV: 1920×1080 pixels
  • 4K UHD TV: 3840×2160 pixels
  • 27″ iMac (5K Retina Display): 5120×2880 pixels
  • Large Outdoor LED Billboard: Varies, but can range from thousands to tens of thousands of pixels in width and height, depending on the size and resolution of the billboard.


When creating a presentation to be shown using a 4K screen, consider the pixel dimensions of the screen. A 4K projector typically produces 3840×2160 pixels. To ensure your images look their best on the 4K projector, you should aim for image dimensions that match or exceed this resolution. This ensures that your images will fill the screen and take full advantage of the 4K resolution, resulting in high-quality visuals.

Using lower-resolution images may lead to pixelation or a loss of image quality when displayed on a 4K projector. The exception would be if the images are not intended to fill the full screen in your presentation.

Popular computer screen formats

The most popular screen dimensions for home computers, and laptops:

  1. 1920×1080 (Full HD): This is one of the most popular resolutions for both laptops and desktop monitors. It offers a good balance between image quality and performance.
  2. 2560×1440 (2K or WQHD): This resolution is commonly found in mid to high-end laptops and desktop monitors. It provides excellent image clarity.
  3. 3840×2160 (4K UHD): 4K screens are becoming more common, especially in high-end laptops and larger desktop monitors. They offer incredible detail and sharpness.
  4. 2880×1800 (Retina Display): This is a common resolution for Apple MacBook Pro laptops. It’s a high-resolution option that provides exceptional clarity.
  5. 1280×720 (HD): Although less common in newer laptops and desktops, it’s still found in budget-friendly devices.
  6. 1680×1050 (WSXGA+): This resolution was popular in older laptops and some monitors. It’s less common in modern devices.
  7. 3440×1440 (Ultrawide QHD): Ultrawide monitors have a 21:9 aspect ratio and offer a wider viewing experience. This resolution is a common choice for ultrawide displays.
  8. 1600×900: Often found in budget laptops and older displays, this resolution is less common in newer devices.

It’s worth noting that screen dimensions can vary, and manufacturers may introduce unique sizes and aspect ratios. However, the resolutions listed above are some of the most prevalent as of January 2022. Always check the specifications of the specific laptop or monitor you are interested in for the most up-to-date information.


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