Overview
Resolution is a term that may confuse people but if we are to get into the art of graphic design then we must know various terms such as high resolution images or low resolution images. We need to familiarize ourselves with changing the resolution of an image.
This tutorial will teach you all about resolution, what it means as it pertains to the images for which we are working and the computer hardware capabilities.
Enlarge these images. Check out the difference in quality. When viewing on a mobile device, zoom in on the images to see the difference in quality.
Example 1
Example 2
What does resolution mean?
To answer this question, we must first understand another two terms and one of those terms is called pixel. A pixel is a very small unit of measurement. A pixel is used to measure the width and height of an error. We will see a pixel abbreviated as px. This measurement is used to measure your monitor's display capabilities. The easiest method to explain pixels is the more pixels that are allowed, the more detail can be provided within an image.
We might have heard of a 1080p monitor or television. While the “p” stands for progressive and not for pixel, this does provide 1,920px in width by 1,080px in height. Likewise, we may have heard of a 4k monitor. These 4k monitors provide 3,840px in width by 2,160px in height providing a more clearly defined image on the screen.
The height and width of images can also be measured in pixels amongst other measurements, such as picas, that are outside the scope of this tutorial. Pixels are one of the most common measurements for an image since they are also used to measure the resolution of a monitor and it becomes easier to determine how the image will appear on the monitor when using the same unit of measurement.
The second term we want to become familiar with is ppi or pixels per inch. Pixels per inch directly relates to how pixels we will fit within an inch of the image. The average image we see has 72 ppi but the generally accepted ppi is typically around 300 for the image quality to appear properly when in printed form.
Resolution, as it pertains to images, means the amount of pixels contained within that image and the amount of ppi. It should be noted, the term “size” and the “height and width” of an image are often incorrectly intermingled when discussing images. It is important to note that officially the “size” of an image refers to how large the image is in kilobytes, megabytes or gigabytes which equates to how much space that image will take up on the hard disk of the computer. This intermingled term pertains to when people refer to resizing the image which refers to reducing or increasing the number of pixels contained within the image which in turn either reduces or increases the size or storage space utilized for the image on the hard disk.
There are no set standard requirements for the height and width of images on a computer so they can be anything, even 1px in width by 1px height or even 100px in width by 10,000px in height. There are individual requirements that software developers put into the software for which they program that will not allow images greater than a specific height or width in pixels nor will they allow an image greater than a specific size and there are sets of standards for images on webpages and learned knowledge that should be adhered to in order to make the webpage much more user-friendly, such as resize your images and properly compress them for faster loading and do not put an image onto a webpage that is 20,000px in height even if you can tell the browser to change its viewable height and width.
What is viewable size?
Now that we understand what pixels, ppi and resolution mean, let us talk a bit about high resolution images. The high resolution images we work with will be much bigger in pixel size than what most monitor's can view and will have a much higher ppi than average. A high resolution image may have a width and height of 8,000px in width by 6,000px in height or perhaps 16,000px in width and 12,000px in height and a ppi of 300 or more. If we try to view these images at 100% viewable size, we will only see a portion of the full image and we will need to scroll down and scroll over to see the full image. Having to scroll over and up and down would make it impossible for a graphic artist to perform their objective so the programmers created viewable size.
Viewable size automatically adjusts the image on the screen down to a percentage of the real size to allow for full access to the image. Some image distortion may happen to the image when viewed at odd percentages such as 33.3%. This happens with high resolution images because the resolution of the image is much bigger than what the monitor's display capabilities.
Adjusting the viewable size allows us, as graphic designers or graphic artists, to fully edit and zoom in and out as necessary onto the image.
A low resolution image does not have this concern because the height and width are typically below that of the monitor's display capabilities. Low resolution images have no business in a graphic designer's arsenal of images.
What is the Difference Between Viewable Size and Resolution?
To further drill this point home, the biggest difference between viewable size and resolution, as it pertains to viewing the image on the monitor, is the actual height and width of the image being viewed within the photo editing software and the ppi level of the image. If the actual pixel size is 4,200px in width and 2,400px in height then the full size of the image will not show up at 100% viewable size on a 2k or 4k monitor. We lower the viewable size within the software, for high resolution images, to allow us to see the full image and not have to scroll over or up and down while attempting to edit the image. While pixels per inch is directly related to resolution, unless we are creating the image from scratch, have access to the original image or are importing the image from our camera in RAW format, we have little control over the ppi for any images for which we wish to edit. We can, for example, increase the ppi for the image that we are working with from 72 to 300 but that will cause the image to become blurry at 100% viewable. We will discuss more detail on increasing the size of low resolution images later in this tutorial.
What is HD?
HD stands for high definition. It is generally accepted that this term refers to any video that is equal to or over 720p. However, if you have ever seen an interlaced 720i and progressive 720p television side by side with the same images, the difference between the two is virtually non-existent and only someone in the field knowing what to look for would be able to point out the differences.
HD is more of a marketing term than anything but for the sole purposes of this tutorial and speaking about the resolution of images, we are going to define HD as any image that is of high quality, meaning it has not been compressed so much that the defining characteristics of the image are unrecognizable, has at least 72 ppi and has at least 720px in height by 1,280px in width.
While, by our standards, we will consider an uncompressed image with a resolution of 1,280px by 720px with at least 72 ppi, a high definition image, it is important to understand this is not considered a high resolution image. If we need to view this on a 4k or 8k monitor, this image is rather small and will be considered a low resolution image because it is not greater than the resolution capabilities of our monitor and is well under the 300 ppi level that has generally been accepted for excellent printing.
What is 4K?
4k refers to videos and images. While the video resolution at a 16:9 ratio is 3,840 pixels in width and 2,160 pixels in height, the images also refer to an image that is the same height and width.
What Happens When I Increase the Resolution from a Low Resolution Image?
When we manually increase the resolution of an image, we are increasing the number of pixels necessary to create the image. The computer has to automatically fill these pixels in with the closest color so it must guess at what color must be inside the newly created pixel. This results in a blurry image because the computer has basic and rudimentary instructions when performing this task and it is not smart enough to make this determination without the proper programming.
Let us take a baseball encased in a small glass case that was shipped to us within a box. It fits in that box nicely and covers that entire area of that box. Now remove that encased baseball and put it in the doorway. Now, make that case and baseball fill up that doorway space so there is no space left behind it. At this point, we should be saying that's not possible and for the most part, we are correct. We could smash the case into oblivion and rip the baseball apart and attempt to replace the space that way but then we wouldn't be left with the original object intact.
Increasing the resolution of an image works the same way as the analogy. The computer has to find a way to fill in the blanks and while there are services that claim they can do this quite well, the standard user's computer does not have this capability natively so we end up with a blurry picture.
What Happens When I Decrease the Resolution from a High Resolution Image?
We can always decrease the resolution of an image. The computer is excellent at removing colors within an image and still maintaining the integrity of the original composition. Changing a high resolution image to a low resolution image is not a problem in most computers as long as the software being used supports this function.
