Even though our eyes still outperform any camera, in recent years digital camera sensors have gotten much better at capturing not just the brightest or darkest portions of a scene, but the brightest and the darkest portions. In this sense, the term Dynamic Range refers not to the lighting conditions but to the capability of the image sensor inside your camera. Some models like the high-end Nikon D or Canon 5D Mark IV are so advanced that a single RAW image fro these cameras can be processed so as to reveal data that might otherwise be lost.
For instance, when I shot the sunrise below I exposed for the highlights so I could get a nice clean picture of the rich colors in the sky, but the side effect of this was that the ground went entirely black. Thanks to the technology baked into the sensor of my Nikon , the camera captured far more data than what you can see initially. I shot in RAW at ISO which meant that I could take advantage of the bucketloads of data that were embedded in this picture and I was able to recover a huge amount of information from those shadows.
The same image, but with the shadow levels boosted significantly in Lightroom. Another example, perhaps a more realistic one, showing the importance of having a camera sensor capable of capturing a high degree of dynamic range can be seen in the following images.
The first image is straight out of my camera Nikon D While the background elements are fairly well exposed, the squirrel and tree are much too dark. Since the scene itself had such a high degree of dynamic range it made getting a proper exposure tricky.
Thankfully I was able to use Lightroom to pull up a lot of data in the shadows that would otherwise be lost if the sensor had a lower degree of dynamic range. Unedited, with a well-exposed sky and underexposed subject. A couple of clicks on my computer resulted in the final image which is vastly improved over the original. Dynamic range is another way of stating the maximum signal-to-noise ratio.
To use sound as the example, this is the ratio of the loudest undistorted signal to that of the quietest discernible signal in a system as expressed in decibels dB. In images and sound recordings, the range that can be captured by a camera or microphone is more restricted than what might be perceived by a human who is standing at the location of that camera or microphone.
Dynamic range is therefore limited by the darkest tone where texture can no longer be discerned; we call this the black level. The black level is limited by how accurately each photosite can be measured, and is therefore limited in darkness by image noise.
Therefore, dynamic range generally increases for lower ISO speeds and cameras with less measurement noise. Techncal Note : Even if a photosite could count individual photons, it would still be limited by photon noise.
Photon noise is created by the statistical variation in arrival of photons, and therefore represents a theoretical minimum for noise. Total noise represents the sum of photon noise and read-out noise. Overall, the dynamic range of a digital camera can therefore be described as the ratio of maximum light intensity measurable at pixel saturation , to minimum light intensity measurable above read-out noise.
The most commonly used unit for measuring dynamic range in digital cameras is the f-stop, which describes total light range by powers of 2. Depending on the application, each unit f-stop may also be described as a "zone" or "eV. Scanners are subject to the same saturation:noise criterion as for dynamic range in digital cameras, except it is instead described in terms of density D.
This is useful because it is conceptually similar to how pigments create tones in printed media, as shown below. The overall dynamic range in terms of density is therefore the maximum pigment density D max , minus the minimum pigment density D min.
Unlike powers of 2 for f-stops, density is measured using powers of 10 just as the Richter scale for earthquakes. A density of 3. Instead of listing total density D , scanner manufacturer's typically list just the D max value, since D max - D min is approximately equal to D max. This is because unlike with digital cameras, a scanner has full control over it's light source, ensuring that minimal photosite saturation occurs. For high pigment density, the same noise constraints apply to scanners as digital cameras since they both use an array of photosites for measurement.
Therefore the measurable D max is also determined by the noise present during read-out of the light signal. Dynamic range varies so greatly that it is commonly measured on a logarithmic scale, similar to how vastly different earthquake intensities are all measured on the same Richter scale. Here we show the maximum measurable or reproducible dynamic range for several devices in terms any preferred measure f-stops, density and contrast ratio.
Move your mouse over each of the options below to compare these. Note the huge discrepancy between reproducible dynamic range in prints, and that measurable by scanners and digital cameras.
The human eye can perceive about 20 stops of dynamic range in ideal circumstances. This means that the darkest tones we can perceive at anyone time are about 1,, times darker than the brightest ones in the same scene. This is how you can still see details in dark shadows on a bright, sunny day. Cameras have a narrower dynamic range than the human eye, although the gap is closing. The best modern cameras like the Nikon D can achieve just under 15 stops of dynamic range in any one photo.
Most digital cameras get somewhere between 12 and 14 while film negatives can get up to about All the shadow detail in the bushes is basically black but the sky is blue. Now you can see the shadow details, but the sky is white. One problem with talking about dynamic range is that while cameras can capture 14 stops, the best screens can only display about 10 stops.
Professionally printed photos get about the same. Instead, you have to make tradeoffs. To do this, I brightened the shadow detail and darkened the highlight detail.
This is pretty close to the limit of what my camera can do. The transition between them and the sky looks funky because of it.
In HDR photography, you combine multiple exposures to create a single final image. As you can see, the sky and bushes are both pretty well exposed, although there is some weird coloring going on, which is one of the chalenges with HDR photography. To read more about how HDR photography works, check our full guide. Browse All iPhone Articles Browse All Mac Articles Do I need one?
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