![]() ![]() When this happens on a densely populated sensor, it’s easy for the charge from one pixel to overflow to neighbouring sites, which is known as blooming. The increased capacity of larger pixels also means that they can contain more light before they are full – and a full pixel is essentially a blown highlight. This is standard on basic cameras and usually cannot be deactivated, unlike on some advanced cameras where the option to do so is provided (meaning you can take more care to process it out later yourself). Noise reduction technology, used in most cameras, aims to cover up any noise which has formed in the image, but this is usually only attainable by compromising its detail. As its pixels can be made larger, they can hold more light in relation to the noise created by the sensor through its operation, and a higher ratio in favour of the signal produces a cleaner image. The main attributes which separate images from compact cameras (with small sensors) and those from DSLR, CSC or compact camera with a large sensor are dynamic range and noise, and the latter types of camera fare better with regards to each. More pixels can mean more detail, but the size of the sensor is crucial for this to hold true: this is essentially because smaller pixels are less efficient than larger ones. As helpful as this is to manufacturers from a marketing perspective, it did little to educate consumers as to how many were necessary – and more importantly, how much was too much. This has now escalated up to the 20MP compact cameras on the market today. That barrier was soon broken but sensors continued to be developed with a greater number of pixels, and compacts that once had two or three megapixels were soon replaced by the next generation of four of five megapixel variants. The more the merrier?Īt one point it was necessary to develop sensors with more and more pixels, as the earliest types were not sufficient for the demands of printing. The alternative to this system the Foveon sensor, which uses layers of silicon to absorb different wavelengths, the result being that each location receives full colour information. This system means that each pixel only receives colour information for either red, green or blue – as such, the values for the other two colours has to be guessed by a process known as demosaicing. For it to sense different colours a mosaic of coloured filters is placed over the sensor, with twice as many green filters as there are of each red and blue, to match the heightened sensitivity of the human visual system towards the colour green. So, an image may eventually appear as a collection of different objects and colours, but at a more basic level each pixel is simply given a number so that it can be understood by a computer (if you zoom into any digital image far enough you will be able to see that each pixel is simply a single coloured square).Ī well as being an analogue device, a sensor is also colourblind. As the charge output from each location is proportional to the intensity of light falling onto it, it becomes possible to reproduce the scene as the photographer originally saw it – but a number of processes have to take place before this is all possible.Īs sensor is an analogue device, this charge first needs to be converted into a signal, which is amplified before it is converted into a digital form. This process creates millions of tiny wells known as pixels, and in each pixel there will be a light sensitive element which can sense how many photons have arrived at that particular location. Funnily enough, this bears many similarities to traditional photographic processes, such as those used in a darkroom when developing film and printing. This is where patterns of the circuitry are repeatedly projected onto the (sensitized) wafer, before being treated so that only the pattern remains. While the process of manufacturing a sensor is well outside of the scope of this feature, what essentially happens is that wafers of silicon are used as the base for the integrated circuit, which are built up via a process known as photolithography. But first, what exactly is a sensor? What is a sensor?Ī sensor is a solid-state device which captures the light required to form a digital image. The following feature looks at these in more detail, and at sensors in general. Each type of sensor bears both advantages and disadvantages – with such a choice on offer it pays to understand what these are, particularly if you are considering investing in a new model. ![]() Consumers now have the option of a number of different cameras with differently-sized sensors, all at the same price point. ![]()
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