Understand Print Image Resolution for Quality Prints

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Author: Gustavo Baner
First Published:
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“My Images Look Great on My Screen But Print Badly” - How to Fix the Issue.

Many clients and graphic designers not familiar with the world of print have a limited understanding of why this happens. As an online printing company that sees that issue a lot, we created this resource in the most logical and clear way that we could think of. WWhat you're seeing is called "resolution mismatch" or "pixelation", and we'll help you fix it!

To understand the issue and be able to select proper images for your printing projects, we’ll analyze the issue in a few steps. The scope of this article is restricted to comparing quality and pixelation effects happening on screens of devices and computers, and printed versions on digital output. We purposely leave large format printing out because there are different variables involved. We will analyze the specific topic in a separate article. I’ll describe the concepts first and then we’ll dive into the specifics of what makes a good image on the screen Vs what makes a good image for printing

Interesting Fact: Psichologysts and resarchers study how human perception is affected by but what they call "quantization" of an image, which is the pixelation. We have linked some valuable resources if you want to deep even deeper. Here is a link: Published books and resources about the topic

Understand Print Image Resolution for Quality Prints

What is Image Resolution? What is Image Density?

Image Resolution refers to the level of detail an image holds. It’s determined by the number of pixels or dots contained within an image. The more dots in an image, the more detail is in the image itself.

We usually talk about “pixels” when we refer to images and screens. We refer to “dots” when we refer to images printed on paper.

There are two physical dimensions to be considered for an image: width and height of an image.

Image Density - DPI / PPI : The density is measured in “dots per inch – DPI” or “pixels per inch – PPI”

The density tells us about how concentrated the dots are in a specific area. The more concentrated the dots, the closer and tightly packed, the better an image looks.

Tip #1 – The more dots that an image has in a certain dimension, the better the image look

Image resolution

Image resolution

Where Do Large, High-Resolution Images Come From?

  1. Digital Cameras:
    1. Professional and High-Quality Models can capture images very detailed images
    2. Some smartphones, when set correctly, can serve in some cases for print
    3. Images generated by good cameras or smartphones, transmitted via text messages or messenger applications are usually not good. The transmission degrades the images in a way that the detail can’t be recovered
    4. Even when creating artwork that is small, always keep a copy of the most detailed version of the pictures safe so that you can reuse them in the future.
  2. Scanning Devices:
    1. Photos, artwork and documents that are scanned with high quality scanners at a high resolution of 300 or 600 DPI might be suitable to print size matches the scanned item.
  3. Design & Illustration Software:
    1. Programs like Photoshop, Illustrator and Corel Draw can produce very high-quality artwork, provided that the settings used match to your output intention (if you want to print the artwork more detailed artwork is required)
  4. Stock Photo Websites:
    1. Not everyone has access to high quality cameras, nor the opportunity to shoot a good picture that works well for a specific project. Stock photo websites compile images provided by photographers and make them available to the public. Some websites are free, but most of them require a reasonable charge to allow the use of their images.
    2. There are plenty of stock photo websites, and image banks. Not all the images in every bank have a big size and high-resolution download option that matches the “printing” intent. Check the pixel size of the images, which is always provided, and use the chart that we are linking to as a reference.
    3. On this chart we have outlined suggested image sizes as measured in pixels and megabytes, as a reference. Click on this link to see that resource
    4. Here are a couple of FREE STOCK PHOTO WEBSITES. The images are mostly provided by amateur photographers and enthusiasts willing to share their work. We are just listing these. Not necessarily endorsing them. Use them as per your convenience. There is no specific order to the list.
      1. https://unsplash.com/
      2. https://pixabay.com/
      3. https://www.freepik.com/ - you can access certain images free of charge, if you credit the source

Practical Demonstration: Image on a Screen

This section illustrates how using images that appear the same on the surface but have underlying differences can lead to significantly different results. We’ll uncover something that makes a huge difference!

My team downloaded the same image twice from the same stock photo website, www.freepik.com. To accommodate for different case uses, the platform makes available the same image in several sizes.

We downloaded a SMALL SIZE version with a file size of 73KB, The BIGGER SIZE version creates a file size of 270KB. From a file size perspective, the bigger file is about 4 times as big.

Even with that difference in file size, the thumbnail that represented the images on the stock website looked the same.

We knew though that there would be significant differences.

I am sharing a detailed area of the image: Two hands are holding a smart phone.

The smaller low resolution version is on the left side, and a bigger high-resolution version is on the right side.

We know from the previous section that the higher the resolution of an original image, the higher the level of details that the image will have.

The blurry details of the hand and the cell phone on the low-res image on the left compared to the right might trigger some aha! thoughts.

Image showing high resolution

Low resolution image | Screenshot File Size: 73K

Image showing high resolution

High resolution image |Screenshot File Size: 270 K

How are these two images different from one another?

Did you know that the size of an image is measured in IMAGE PIXELS? The word PIXEL comes from “Picture Element”. Each pixel represents a specific color and brightness value. Collectively they form a photograph.

The Low-Res image measures 1117 (horizontal measurement) pixels X 1187 (vertical measurement) pixels. The total number of pixels (multiplying both) is 1,325,879 pixels. That is about 1.32 Million pixels

The High Resolution version measures 2114 x 2141 pixels. Multiplying both, the total number of pixels in this case is 4,526,074. That is about 4.5 Million pixels

The bigger and high resolution image contains almost 4 times as much data!

4 times is the same number that came up when comparing the file size. So the file size gives us some important information from the get-go.

The observation is consistent with what we explained in the previous section. More dots concentrated in a similar area (in this case the size of the image) create a much richer and more detailed image.

On Screens: Requirements for a Good Image Quality

What Happens on Screens: To understand this problem, we’ll analyze images that look good on a screen and compare them with images that don’t look good on a screen.

FACTS ABOUT SCREENS: Before comparing, let’s keep the following facts in mind: (a bit technical but important to understand)

  1. Screens are made with tiny light emitters (kind of tiny light bulbs). Each of those is identified as a DEVICE PIXELS. They are part of the physical world.
  2. Each pixel can be instructed by the device’s brain (a smartphone or a computer) to display any color among 16 million possible colors that they can show.
  3. The color gamut is big. There are so many nice colors that can be displayed.
  4. Number of Device Pixels on PCs: A regular computer monitor for PCs typically packed 72 pixels in an inch (72 PPI). More modern 4K monitors pack about 163 PPI
  5. Number of Device Pixels on Apple computers. It used to have 96 PPI. Their modern Retina screen pack about 218 PPI
  6. Device Pixel’s Size: Each physical pixel on the screen measures about 0.3mm x 0.3mm. or 0.012” x 0.012”. Very very tiny.
This is how a physical pixel looks in concept. It is very small and square, capable of emitting light

This is how a physical pixel looks in concept. It is very small and square, capable of emitting light

Why do most images on monitors look from acceptable to good? Modern monitors contain well packed and compact pixels. Each pixel can show an immense number of colors.

The Outcome: you get to see an image on a screen that looks pretty good and balanced, with color transitions that are appropriate. The software that runs the graphic boards that control those device pixels “work hard on the fly” to display the image as good as it can be. Just to be clear: The screen is showing an interpretation of the file. The computer allocates bits of the image into the device pixels.

Viewing Distance: Screens are usually looked at from about a foot on smaller devices such as smartphones. On larger devices, such as larger computer screens or TV screens that can be used as computer monitors, that distance could be 1.5ft to 2ft.

On Print: Requirements for a Good Image Quality

The requirements for files that will be printed is different.

The reason is that instead of showing an image in a monitor via self-lighting pixels, the printed image gets “stamped” on a piece of paper.

Only 4 Colors: Instead of getting millions of color options to stamp each dot, there are only 4 colors that can be used, which introduces a ton of constraints.

The reflection of the light that his that stamped image is what will create the color in our eyes.

FACTS ABOUT PRINTING:

  1. The color that comes out of a process color printing press is only visible to our your eyes: This is rarely talked about. The color theory and the technology involved are quite simple in concept. The next section, “effect of viewing distance”, provides additional information.
  2. Just 4 colors are used to print nice colorful images: Full Color Printing is also known as Process Color Printing. The printing process applies tiny dots of ink or toner on a paper substrate. The printing presses just use 4 different colors of ink.
    The colors are known as Cyan (C) a light blue, Magenta (M) a pinkish color, Yellow (Y) and Black (K). The letters CMYK are of universal use to identify those important colors.
    Why just these four specific colors? CMYK inks absorb light in a way that maximizes the tones reflected. The color printing theories started their development in the 1700’s and evolved. It was 1906 when the combination of this set 4 colors started to show the benefits and became the standard.
    This image shows what the four colors used in printing on paper look like

    This image shows what the four colors used in printing on paper look like

  3. Vibrance of Colors: The inks do not emit light as device pixels do, so the vibrance of their colors is much lower than that of screens. The images on screens look stronger and can display more contrast.
    Technically speaking in print, we start with a white paper that reflects the strongest white light. As there is more and more ink on the paper, the white color gets “captured” by the ink and that produces the variety of colors. The color comes as a subtraction of light.
  4. How Many Dots Per Inch can be Printed? For each of the four colors, on some presses you can have 300 dots per inch or less.
    Because there are four colors, and you need to combine the inks to get a specific color, some dots of one color can sit on top of other dots. The next image shows that.
  5. Size of Dots: The size of the dots can vary from tiny, small to larger, as shown on the image. The size allows you to get halftones or gradients from 0% (meaning no ink is printed) to 100 %, when a solid Cyan, or Magenta, or Black, or Yellow are printed.
    Halftones are the way to create a visual color that looks less saturated than the color itself.
    Combining dots of four colors, CMYK, our eyes see many other colors

    Combining dots of four colors, CMYK, our eyes see many other colors

  6. Dots on Paper: 300 per inch. Do you remember from above, that screens show 72 pixels per inch? Well, print on paper requires 300 dots per inch?
  7. Why 300 dots per inch?
    1. The dots must be small enough so that the eye can transform single dots into a merged color at a book-viewing-distance.
    2. You get the color by mixing and overlapping dots made of just 4 colors.
    3. Print does not provide the millions of colors that device pixels can provide.
  8. Image Size in Print Vs Image Size on a Screen. Print needs 300 dots in an inch as opposed to 72 on a screen. This means that an image that on a screen have a size of 1 inch (assuming that it is 72 pixels wide), when printed the same image will only be about 0.25 inches wide… which makes it extremely small.
  9. 8.The images that you use when preparing a job that will print on a press has to be much bigger (probably 4 times bigger) than the file used if the image is going to be seen on a screen. The NATIVE file be bigger.

Image Format and Image Handling

  1. In your cameras or cameras of phones always use the highest resolution that the camera provides.
  2. If you are sending pictures that you shot to an editor or artist, NEVER use applications such as instant messaging or text messaging apps. All of those degrade the images to make it easier to share. The degradation still makes them look good on screens, but won’t print properly (read the last point in this section)
  3. The best files to contain images TIFF or PNG because they support lossless compression. The file size could become huge, but when you are ready with the file, you could export it at the HIGHEST quality levels that JPG permits
  4. Always start with the highest possible resolution image that you have available, even if you know that the print size will be small for a project. A large image can be made smaller at the time or printing. But if the image is small and it has to be enlarged, then you no longer have the necessary details.
  5. Many editing applications alter the image files in different ways. Examples:
    1. Photoshop reduces the resolution of images if you shrink them and does not get the resolution back when you enlarge them. (there are technics that permit that, but you must be an experienced user to take advantage of those features).
    2. Software such as Microsoft Word automatically reduces the size and resolution of imported images to keep the files’ size small. Depending on your version of MS Word, a setting can be used to prevent that from happening.
    3. On other applications, the intent of output must be properly selected BEFORE you start creating a file. If the output intent was originally web, the images might become automatically reduced.
  6. Maintain organized workflows. Identify your files with names such as xxx-large.jpg so that you don’t use a low resolution image instead of a high resolution one.

Effect of Viewing Distance

The viewing distance (VD), the distance between the viewer’s eye and an object that is being looked at, is a critical factor.

VD affects the perception that individuals have about the quality of what they see. Changing the viewing distance, the same element can look “sharp”, “out of focus”, “pixelated”, or even be “undistinguishable”.

Average viewing distances for books, computers and smartphones.

Average viewing distances for books, computers and smartphones.

How much detail can our eyes actually see? Eyes can distinguish details up to a certain extent. The “Visual acuity” is affected by the distance between the observer and an object, and by the distance in between elements that are on display.

When an eye can’t distinguish the details, this is what happens: If the elements are closer together and smaller than the human’s eye resolution capability, our amazing human eyes tend to blend and the images making them a continuous color to the eye.

Perceived Resolution and Quality:

  1. It is not just about the “number of dots” that provides the resolution.
  2. It is about how the dots are laid at a specific viewing distance.
  3. The closer we are to the “thing”, the more detail our eyes can see. Our eyes could distinguish each and every printed dot, even for untrained eyes. If those dots were too big, or the dots repeat themselves because the image has been enlarged (read the next section, ”Consequences of Scaling Images Up”), our eyes start to see that detail, which ultimately gets identified as pixelation.

Considering that when reading a flyer, newsletter, a magazine or any other print publication our eyes get very close to the piece, we can see more details, therefore catch the pixelation easier than on a screen.

Consequences of Scaling Images Up

Avoid it! Native Image Size Matters

Enlargement Explained:

  1. If a native image is 100px x 200 px, the total number of device pixels to show it is 20,000.
  2. We want to enlarge that image to 200 screen pixels X 400 device pixels, doubling the size of what we see on the screen or print. A total of 80,000 image pixels is required, instead of the native 20,000. This is 4 times the number of pixels. The total number of device pixels to show it is 20,000.
  3. “Inventing” what is missing: Because the original image just had 20,000 pixels, and it now needs 80,000, those missing pixels must be “added”.
    1. Screen-based interpolation, resolved by graphic boards (GPUs) and taking advantage of the millions of colors that a device pixel can show, can produce pleasant results. Larger enlargements will show the pixelation.
    2. Print has more limitations: Printer Rips are used. Because print uses 4 colors and dots in variable sizes, the results of interpolation are worse than on screen interpolation.
      A 'small' image gets filled in with inaccurate visuals when it is enlarged. That 'inaccuracy' become pixelation.

      A 'small' image gets filled in with inaccurate visuals when it is enlarged. That 'inaccuracy' become pixelation.

    3. Fill in the Blanks: Those “invented” or generated-out-of-nothing pixels look like areas with lack of detail and lack of differentiation. They are called “pixelation” or “artifacts”
    4. How much enlarging is tolerable? The bigger the enlargement of an image, more and more pixels must be created. If the enlargement is small, the deterioration of the image might not be dramatic.
This small file on the screen seems to look good

This small file on the screen seems to look good

This small file on the screen seems to look good

This small file on the screen seems to look good

If you print this image at this size….

If you print this image at this size….

Picture of the real printed file

Picture of the real printed file showing pixelation

Image Pixelation. More visible in print than on screens

  1. You start to deal with images that don’t exist in the original file so your final output is degraded.


Image Pixelation on Enlarged Images: In this case I want to show you how much an image becomes pixelated when you enlarge it on a screen. This example is representative of every image, not just this one. This is more visible on smaller images.

Step #1: We downloaded an image from a website. The image below on the left shows a screenshot of the picture on the computer monitor.

  1. The size of the image is 200 pixels x 200pixels, 3.7 KB


The chair looks small but decent.

Image Origin: Low res from Internet

Image Origin: Low res from Internet

Image Origin: Low res from Internet - Enlarged on the screen

Image Origin: Low res from Internet - Enlarged on the screen

What we hope that we were able to share with you as clearly as possible:

  1. It is very common to have images that look good on a screen but print terribly bad.
  2. The perceived quality of an image both in print or on a screen are the result of many factors, such as if the image is seen on print or screen, how far away from the object is the observer, the size of the printed dots, the size of the screen pixels, the way in which the file has been preserved for high quality. There are more factors to take into account.
  3. Start with high resolution images, even if you think that the final output will be a small picture. Reducing the size of an image is possible. The opposite is not.
  4. Do not scale images up. If the original image that you are starting from is a large well-made image, a bit of enlargement might be acceptable
  5. If you start with an image found online, just know that your software will enlarge it, but the print quality won’t satisfy you at all.
  6. Always check the properties of your file to know the size and DPI.
  7. When you save a file as a JPG and want to make the file smaller, what you are effectively doing is getting rid of huge portions of the image to save space. You are indeed, reducing the resolution of the image.
  8. Always check with your print provider if you have questions regarding the quality of the images.
  9. If the print provider tells you that XX image is very small and low resolution, do not use software to increase the size of that file. The result will be an even worse image that has been scaled up. Just look for a different high resolution image.

Published Research Resources

  1. "Pixelated Image Abstraction" by Timothy Gerstner et al. (2012): This study presents an automatic method to abstract high-resolution images into low-resolution outputs with reduced color palettes, emulating the style of pixel art. The authors discuss the challenges of maintaining image clarity and detail when reducing resolution, which is pertinent to understanding pixelation in printed images. -
    Link to the source.
  2. Perception of Pixelated Images" edited by Talis Bachmann (2016): This book compiles research on how pixelation affects image perception. It explores the balance between image resolution and the viewer's ability to recognize content, providing insights into how pixelation impacts visual interpretation.
    - Link to the author:
    - Link the book review:
  3. "Avoiding Twisted Pixels: Ethical Guidelines for the Appropriate Use of Digital Image Processing in Scientific Publications" by Michael W. Rossner and Kenneth M. Yamada (2004): This article discusses the ethical considerations and technical implications of digital image manipulation, including pixelation. It provides guidelines on maintaining image integrity, which is crucial when preparing images for publication and can inform best practices to avoid unintended pixelation during printing.
    Link to the author: