In this hyperconnected era of social media and selfies, it can be quite disconcerting to find you look different in photographs than you do in the mirror. There is also a difference in how you look in the front-facing camera vs. your smartphone’s rear camera, so which is the real you?
The difference between a mirror image and a camera image lies in how light reflects and refracts off objects. A mirror image is an accurate representation (virtual image) of an object that occurs when light rays travel in a straight line and bounce off a reflective surface. A camera image (real image) formed via light rays crossing and emerging on an object that we capture on a photosensitive surface (film or digital).
You could, for example, end up arguing with friends on a night out if a mutual acquaintance has a birthmark on the right arm or the left arm, with each party producing their proof in the form of a photograph.
You may even begin to speculate on what caused the switched images, but no one in the group can provide a reasonable explanation. So let us look at the real issues here.
Differences between a Mirror Image and a Photo Image
The difference between a mirror image and a camera image in optics is typically that of a “virtual” image compared to a “real” image. These differ in the focal point of the light rays.
Light rays produce a virtual image when they travel in straight lines bouncing off a reflective surface and creating the object’s image.
A real image is a photo image in which light rays cross and emerge on an object, which we can capture on photosensitive materials.
The reflection (throwing back) and refraction (deflection) of light rays through different media creates a “virtual image,” meaning that the light does not come from where it seems to be; it is fleeting and changes as the subject moves or the light changes.
The fluidity of the virtual mirror image is very different from the static camera image. A camera image is a “real image” where the light focuses on where the object really is.
We can capture it on materials, and it is the closest reflection of how other people observe the subject.
Mirror Image: Refraction and Reflection
The formation of a mirror image starts when light hits a shiny flat surface and reflects (throws back) the image (source).
A mirror reverses the image from front to back, making the image appear backward or the opposite. It does not reverse the image left to right, as we commonly assume.
For example, if you face north while looking into a mirror, your image is facing south, so the reversal is front to back.
To clarify this concept, imagine you have a mole on your left cheek or a birthmark on your right arm. In that case, it will appear on the opposite side in a mirror.
Geometric Optics
The field of geometric optics deals with both reflection and refraction of light rays as the light rays move through a transparent material. Sir Isaac Newton was the first to lay down the three laws of geometric optics.
First, light rays move in straight lines as they move through clear material. Second, when light rays hit a smooth, shiny surface — for example, a mirror — the rays bounce off the surface.
The third pertains to how light rays behave when passing through material such as air and water.
A reflection happens when light rays bounce off a flat surface. The rays remain in a straight line but bounce off the surface in the opposite direction and angle of the surface. This is why objects appear at the same distance from the mirror.
Concave mirrors will concentrate the light reflecting a focal point, and convex mirrors will spread the rays, with the light reflected at different angles.
Camera Image
The science of optics refers to the way light reacts when reflected, refracted, or bent, and it forms the basis of the art of photography.
Cameras capture light rays on photosensitive materials, such as film in older cameras or photosensitive sensors in the more modern digital cameras.
In a photo image, the light rays focus on the actual image. The image becomes visible on film, for example, through a camera lens. The same principle applies to projecting an image onto a big screen, like in a movie theater.
Pinhole Camera
In a pinhole camera, there is no lens, just an exceedingly small aperture, called the pinhole. It is practically the size of a pinprick.
Here, the light from the subject passes through the pinhole and produces an inverted image on the photosensitive material. We know this process as the camera obscura effect.
Light in a vacuum travels at a constant speed; however, it does not travel at the same speed through all materials. It will slow down, bend, and refract, changing its properties as it travels through different materials.
It is this propensity of light that allows us to manipulate the light traveling through camera lenses. The basic properties of lenses and the principles of how we use them have not changed over the years, even though lenses have become more sophisticated.
Modern Cameras
Today, cameras have a simple lens or several lenses, ranging in sophistication. As a simple lens can produce several aberrations, it is best to use a camera with better lenses.
Aberrations make the periphery of the photo image blurred and often enlarge the part of the subject closest to the lens, for example, a nose on a face.
By using several lenses of appropriate shapes, we counteract the aberrations. Sometimes, we use one or more lenses of aspheric shape — thus, with a variable curvature of a paraboloid — rather than just spherical ones.
Paraboloid shapes are curved shapes made with straight lines and mathematical equations, like the symmetrical patterns children like to draw with stencils.
Camera Lenses
Camera lenses consist of a series of glass plates that are either convex (curved outward) or concave (curved inward) and, in some cases, with variable curves.
In a film camera, the lens sends the light rays from the image to a film strip. In a digital camera, the lens sends the light rays to a digital sensor.
The shape of the lens determines the amount of distancing light that needs to travel to converge properly on the image plane. In modern lenses, we measure this distance in millimeters and refer to this as the focal length.
Focal Length
Focal length also determines the type of image your camera captures. It is the basic description of your camera lens; the lens focuses at infinity (source).
The focal length determines not only the angle of the view but also the magnification. The angle of view refers to how much of the scene the camera captures, magnifying how big the objects will be in the image.
When you take photographs, you need to pick your lens to suit your outcome. For example, the longer the focal length of a lens, the higher the magnification and the narrower the view of the lens.
In contrast, the shorter the focal length, the wider the angle, and the lower the magnification.
Thus, if you want close-up photos, you need to use a lens with a long focal length, and wide-angle shots taking in a whole vista would require a lens with a short focal length.
A prime lens has a fixed focal length, but zoom lenses have a variable focal length, giving the photographer room to play with. Prime lenses also provide a bigger aperture, which is great for low-light photography and a shallow depth of field.
There are three basic lenses: normal lenses, wide-angle lenses, and telephoto lenses.
Our article on dilation vs. dilatation discusses the theory of transformation that produces an image of a different size but is the same shape as the original.
Review
All these explanations can become very confusing, so it is prudent to summarize the differences for ease of reference in a table (source).
| Plane Mirror | Pinhole Camera |
|---|---|
| The mirror image is a virtual image. | The camera image is real. |
| In a mirror, the image formed is always equal to the size of the object. | The image formed by the camera may or may not be equal to the size of the object. In some cases, it will be smaller and in others bigger. |
| The image formed in the mirror always remains erect. | The image in the pinhole camera is inverted. |
| The mirror image is always dynamic. | A photo image is static. |
| A mirror image is 3D. | The photo image is 2D. |
| The mirror image reflects light. | A photo image cannot reflect light. |
| The mirror image is less accurate. | A photo image is a more accurate reflection of how people see you. |
| The mirror image preserves information about distance from an object as it reflects light that comes in at a particular angle and in just one direction. | In a photo image, the object appears as far away from you as the photo is from your eyes. |
| In a mirror, image objects will remain in focus. | In a photo image, you can manipulate the lenses to make objects appear in focus or not. |
Why Do You Look Better in the Mirror than in a Photograph?
It is frustrating to take selfies using different angles and lighting that never look as you did that morning in the mirror. However, the image we see in the mirror is a false image, leading us to believe we look better than we do.
A mirror is not an accurate depiction of what you really look like and does not translate well to a photograph.
The Mere-Exposure Hypothesis
In the 70s, a famous experiment took place where 33 undergraduate female students and their friends examined photographs of the females, showing their mirror image and their true image side by side, with a single frontal photograph (source).
Surprisingly, the female subjects in the two studies preferred their mirror image to their actual image, whereas it was just the reverse for their friends.
The female subjects preferred the mirror image since they see it every day, whereas their friends preferred them as portrayed in the photos.
Why Is This?
The reason you look better in a mirror rather than in a photograph is linked to your brain producing a 3D image of yourself, making you look more flattering to yourself in a mirror.
In real life, you see things in 3D, whereas, in a photograph, you see a two-dimensional object.
The mirror image is reversed, but that is what you are used to seeing. In photos, you appear flatter and broader than you are — remember, the camera adds 10 pounds! — especially with the wide-angle camera lenses in the older cell phones.
The lens expanded the middle of the picture, and it was crimped at the edges.
Today, cameras have four or more lenses for different circumstances, scientifically positioned to reflect the light in such a way as to give the results you would expect. Wide-angle lenses, for example, are suitable for landscapes or groups.
There is also the case of symmetry. Again, in a mirror, your face and body will be different from what a photo shows.
Again, you are most accustomed to seeing yourself in a mirror, and, once again, your brain compensates for that. As a result, seeing yourself in a photo can be surprising.
Also, as faces are rarely symmetrical, we can notice things in photographs that we do not see in the mirror.
Front Facing vs. Rear-Facing Cameras on a Smartphone
The rear camera, on the back of the phone, is the primary camera, and it has a better dynamic range. The dynamic range denotes the range of light strengths and the number of levels from the shadows to the highlights.
It has a flash for night photography too. The back camera is great for scenic photography and has much better resolution and a wide-angle lens.
The front camera was initially intended for video calls in 2003 and usually has a lower resolution, which attributes to space issues on the front of the camera, caused by the size of the screen, and based on common usage of the phone.
Very few smartphones have similar or better front-facing cameras. The lower pixels in the front often lead to blurry photographs.
When you take a selfie using the front-facing camera, the image will appear “flipped” as in a mirror image. It is not actually reversed but reflected backward.
It appears as if reversed left to right, but it merely reflects the light back at you. So, for example, if you have a cup in your left hand, it will appear as if it is in your right hand.
When you take a selfie with front-facing cameras, your picture looks distorted. Objects such as lips or noses closest to the lens appear much bigger, mostly because it contains simple lenses.
The further away you hold the camera from your face, the better you will look. If you hold the camera below your face, your neck will appear enormous. This article was written for strategiesforparents.com.
Many selfies taken in a mirror have been ruined by seemingly enormous hands holding the smartphone. This is why someone invented the selfie-stick.
Final Thoughts
Mirrors and lenses produce real or virtual images captured or not, reversed or not, and inverted or not. In real life, the photo image gives a better reflection of what you actually look like to other people.
In contrast, the mirror image is the view we normally prefer due to it being so flattering.
The advent of the selfie has spurred obsessive posting of these images on social media to convey to the world what we look like. Some people take selfies in the mirror because they know they look better in the mirror than in a photograph.
Thus, they find the images as frustrating as photo images, as they now combine a mirror image with a photo image. Now that you understand how photo images and mirror images differ, you can discuss some of these principles with other English speakers.