Basically, the dynamic range is the ratio between lightest and darkest regions (also known as contrast ratio). Yet when we’re talking about measurement devices, things get a bit more complex.
Without further ado, here are some useful things to know about dynamic range:
– There is no true black or white in the real world.
Though it might seem so through video transfer, when you convert VHS to DVD, or in any other situation, actually there are just varying degrees of light.
– A digital camera’s dynamic range is determined by a photosite’s size and content measurement.
It is the ratio of two measurable light intensities: maximum light intensity to minimum light intensity. The unit for measuring this range is f-stop.
If we were to compare a compact camera to a digital SLR camera, the latter has a higher dynamic range. Yet when it comes to consumer cameras, the dynamic range is limited by the darkest tone (the black level) and the limitations have to do with image noise. So the dynamic range will increase for devices with less measurement noise and low ISO speeds.
– The human eye perceives a higher dynamic range than a camera.
However, the eye’s dynamic range and sensitivity changes according to contrast and brightness. The eye is highly adaptable and it can detect very high dynamic ranges instantly.
– Dynamic range varies a lot.
It is usually measured by a logarithmic scale, similar to a standard Mercalli scale that measures various earthquake intensities.
There are big differences between reproducible dynamic range in prints and the ones measured by digital cameras or scanners. Dynamic range varies greatly depending on ambient lights.
– The contrast ratios for many display devices are not always accurate.
There are no strict standards so they could be simply exaggerated. So it’s important to pay attention not only to the contrast ratio, but also to the surrounding luminosity.
– There is a lot of uncertainty concerning the relevance of image bit depth on recordable devices.
This even applies to the best picture and negative scanners or to digital scanners for photos. There are two types of dynamic range: recordable and displayable one. The main way to encode a very vast dynamic range that is not altered by bits spread over the tonal range is using HDR image file in a photo editing program such as Photoshop. At the moment, this is considered to be the only standard solution.
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