Warning: Objects Within Your Browser Window Are Smaller Than They Appear!
If you see an object on your computer or phone that you want to interact with, and it looks too big, let’s say a piece of text or a drop-down menu, then it is actually much smaller than it appears. Most people don’t know that objects within your browser window are smaller than they appear. The reason is because the pixels in any document – whether they be text or images – are rendered at a fixed size. So if an image appears to be larger than the actual size of its pixels, the human eye will see what seems to be an enlarged image as it was intended by its author. This is a side effect of how the human visual system works. If you are interested, you can read more about it here.
I’ve been dealing with this for years and it seems to be a limitation of the current HTML standards. I have written about this in many places, including my own blog.
In fact, I have recently posted another article on this subject, " Why Is It that Web Images Sometimes Look Much Smaller Than Their Actual Size? ". This article explains the reason for this illusion: if we display an image that has been rendered at a fixed size (say 16x16 pixels), then our vision will perceive any object larger than that size as being larger than 16x16 pixels.
What is the purpose of this article?
I usually try to provide solutions to problems such as this. This time, I want to give you just a glimpse into why we experience this illusion as I talk about it for only a few sentences. One thing I'll say up front is that most of the information in this article comes from several articles by David Mandel, including his free ebook " The Trouble With Pixels " and " Why Is It that Web Images Sometimes Look Much Smaller Than Their Actual Size? ". So thank you, David.
That is why I wrote this article – to get you to read David’s articles. He provides lots of information on all sorts of things that HTML developers and users need to know.
In fact, I have recently created a web page at the top of my blog where I have added links to a selection of articles related to web development by other authors. Go check that out, if you like.
As I said, most of the information in this article comes from David Mandel’s articles and from Wikipedia . But as always, I added some extra bits here and there based on my own experiences with this problem.
Let’s talk about how we see and perceive images on the Web.
When you look at a web page, what you are really looking at is an image. Pictures are everywhere on the Web. In fact, there is an image on every page in this blog right now! If you look closely at any of the photos that I have uploaded to this blog, then you may see that they have been shrunk down so they fit inside a PNG file with a width and height of 72 pixels and 96 pixels respectively.
I would like to talk about how the human eye works to help you understand why images on the Web can look small when they are actually large and why images appear smaller than their actual size.
When we see and perceive an object, our brain takes the information that we see and computes a model of that object. The model will be accurate in proportion to the information available to our senses. But sometimes we are not only limited by what our eyes can see, but also by what the eyes can compute based on the information they receive from our brains.
We’ll talk more about this in a bit, but for now let’s just review some of the basics of how image perception and cognition works.
When we look at an object, like this photograph of my garden, then the visual system (the eye and later brain) takes in light reflected or emitted from that object. The eye is highly sensitive to small variations in reflected light. So the visual system is doing a lot of computation to take in light and get an idea of what it is looking at.
The visual cortex has two major parts: one in which we see the world through our eyes, and another part which computes a model based on that information taken from the previously mentioned visual cortex.
What exactly happens in the brain as you see objects on your computer screen or mobile device? Let’s look at it from a slightly different angle.
In my brain, I take in light coming from the object that I am looking at – you. I don’t see the color of your clothes or skin, but I do see the shape. From that information about your shape, my visual cortex computes an outline or a profile of you.
Once that model is computed, then the visual cortex will begin to color it and to fill it with other information as necessary to create an image of what you look like. This entails storing a lot of information about your irregular shaped head into memory such as brightness, color and texture at different points on your face. For example, the visual cortex will assign a certain color to your hair and skin, where that color is determined by the frequency of light reflected from your head.
Your flesh will be either a lighter or darker shade of gray based on these amplitude variations. The color of your eyes and their frequency details will also be stored in memory along with information about how shadows work.
And I’m not even talking about any hair you might have on the top of your head or the back of your neck. We’re just talking about taking in light reflection from a relatively small part of your face (your head). This is why we see objects differently than what they look like when we take a photograph.
There are lots of other details that are stored in memory such as the time of day, even the time of year (when viewed at different locations on a planet), and even the tone quality or color of daylight. The visual cortex will also store information about how light changes over time. I have written about these topics before and you can read more about it in this article.
On top of everything else, the visual cortex will also treat images like photographs in many other ways, such as relating them to our memories, age and gender. And last but not least it renders your face into a 3D rendering based on all that information.
And, of course, all these things occur in your brain without you having to think about it. But thinking is what I am going to talk about next.
Once you know all of the details that are stored in memory as we view a particular object, then you start to understand why we perceive images differently than they really look. Our brains take in the information and process it very quickly because we pick up on a lot of information very quickly.
And sometimes this information can be wrong or somewhat misleading because it is not completely accurate. This happens all the time with photographs, but we normally don’t notice unless something is wrong with our minds or eyesight.
Conclusion
To see is to compute, but sometimes we don’t compute or process information as accurately as we would like.
In many ways, seeing or perceiving is not always the same as seeing clearly. This explains why the images in this blog appear to be smaller than they really are.
Every time you resize an image in your mind from one point of view, you are actually computing a new image model which may be different from the model that other people see on their computer screens or mobile devices. But there is no way for you to know for sure unless you know what kind of device and/or browser that person is using.