Pinhole cameras how does it work

Hopefully though you don't need very complex cameras to produce images. In fact it's quite the opposite. You can take photographs with a very simple imaging device called a pinhole camera which is just a box with a small hole on one side and photographic film lying on the other. Images produced by pinhole cameras are much easier to reproduce and less costly than those produced with more sophisticated cameras, and for this reason, the pinhole camera is actually the model used by most if not all 3D applications and video games.

Let's start to review how these cameras work in the real world and build a mathematical model from there. Most algorithms we use in computer graphics simulate how things work in the real world. This is particularly true of virtual cameras which are fundamental to the process of creating a computer graphics image. The creation of an image in a real camera is actually pretty simple to reproduce with a computer.

It mainly relies on simulating the way light travels in space and interacts with objects including camera lenses. The light-matter interaction process is highly complex but the laws of optics are relatively simple and can easily be simulated in a computer program.

There is two main parts to the principle of photography:. In computer graphics, we don't need a physical support to store an image thus simulating the photochemical processes used in traditional film photography won't be necessary unless like the Maxwell renderer, you want to provide a realistic camera model but this is not necessary to get a basic model working.

Figure 1: The pinhole camera and camera obscura principle illustrated in , in The Boy Scientist. Figure 2: a camera obscura is a box with a hole on one side. Light passing through that hole forms an inverted image of the scene on the opposite side of the box. Now lets talk about the second part of the photography process: how images are formed in the camera.

The basic principle of the image creation process is actually very simple and showed in the reproduction of this illustration published in the early 20th century figure 1. In the setup from figure 1, the first surface in red blocks light from reaching the second surface in green. However if you make a small hole a pinhole , light rays can then pass through the first surface in one point and by doing so, form an inverted image of the candle on the other side if you follow the path of the rays from the candle to the surface onto which the image of the candle is projected, you can see how the image is geometrically constructed.

In reality, the image of the candle will be very hard to see because the amount of light emitted by the candle actually passing through point B is really very small compared to the overall amount of light emitted by the candle itself only a fraction of the light rays emitted by the flame or reflected off of the candle will pass through the hole.

A camera obscura which in Latin means dark room works on the exact same principle. It is a lightproof box or room with a black interior to prevent light reflections and a tiny hole in the center on one end figure 2. Light passing through the hole forms an inverted image of the external scene on the opposite side of the box. This simple device led to the development of photographic cameras. You can perfectly convert your own room into a camera obscura as shown in this video from the National Geographic all rights reserved :.

To perceive the projected image on the wall your eyes first need to adjust to the darkness of the room, and to capture the effect on a camera, long exposure times are needed from a few seconds to half a minute.

To turn your camera obscura into a pinhole camera all you need to do is put a piece of film on the face opposite the pinhole. If you wait long enough and keep the camera perfectly still , light will modify the chemicals on the film and a latent image will form over time.

The principle for digital camera is the same but the film is replaced by a sensor that converts light into electrical charges. In real camera, images are created when light falls on a surface which is sensitive to light note that this actually also true for the eye. For a film camera, this is the surface of the film and for a digital camera this is the surface of a sensor or CCD.

Some of these concepts have been explained in the lesson Introduction to Ray-Tracing but we will explain them again here briefly. Figure 3: in the real world, when the light from a light source reaches an object, it is reflected back into the scene in many directions. However only one ray goes in the direction of the camera and hits the surface of the film or CCD. In the real world, light comes from various light sources the most important one being the sun.

When light hits an object, it can either be absorbed or reflected back into the scene. This phenomenon is explained in details in the lesson devoted to light-matter interaction which you can find in the section Mathematics and Physics for Computer Graphics.

When you take a picture, some of that reflected light in the form of packets of photons travels in the direction of the camera and passes through the pinhole to form a sharp image on the film or digital camera sensor. We have illustrated this process in figure 3. If you remove the back door of a disposable camera and replace it with a translucent plastic sheet, you should be able to see the inverted image that is normally projected onto the film as shown in the images below.

The simplest type of camera we can find in the real world is the pinhole camera. It is a simple lightproof box with a very small hole in the front which is also called an aperture , and some light-sensitive film paper laid inside the box on the side facing this pinhole.

When you want to take a picture, you simply open the aperture to expose the film to light to prevent light from entering the box, you keep a piece of opaque tape on the pinhole which you remove to take the photograph and put back afterwards. Figure 4: principle of a pinhole camera.

Light rays which we have artificially colored to better track their path converge at the aperture and form an inverted image of the scene at the back of the camera, on the film plane. Sign up for our Newsletter!

Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Camera Basics. How Does a Pinhole Camera Work? A simple pinhole camera. See more pictures of cool camera stuff.

It consists of a light-proof box, some sort of film and a pinhole. When light goes through the pinhole, it creates an inverted image at the back of the box. What is the purpose of using a pinhole camera? A pinhole camera is a simple camera used by photographers.

What is the pinhole effect? It consists of a light-proof box with a tiny hole in one end and some film or photographic paper on the other end. When light rays go through the tiny hole, it forms an upside-down inverted image at the back of the box. We can see a wonderful pinhole camera in nature. Have you ever seen the bright spherical patch of sunlight on the ground when you go under a large number of leaves-covered trees?

The tiny gap between the leaves acts as pinholes, groundworks as a screen, and the Sun acts as an object. When the light comes from the Sun passes through these pinholes and makes images patches on the ground. It is time to put your knowledge to the test by answering a few questions. Funny Jokes. Parenting Tips.

Pinhole Camera. What is Pinhole Camera? If you increase the number of holes, the number of images also will increase. Take an empty shoebox Paint the inner part of the shoebox in black color to make it light-proof. Cut one end of the shoebox and fix a wax paper or tracing paper over the open end. With the help of a sharp pencil or small nail, make a tiny hole at the center of the opposite side.