Amp Glow And Hot Pixels
When you take a picture with a digital camera, as more fully explained in more depth articles, it “captures” the picture set before the lens (which we define as “analog”) and is converted to digital and then the It saves on memory.
The transition from analog to digital has made great strides and cameras of the latest generation they are able to reproduce reality with a very high detail, almost perfect. In fact, almost. And this is because the conversion from analog to digital will never be perfect, there being problems, the limits that can not be exceeded. Obviously we are talking about very small phenomena, often imperceptible to the eye also attentive phenomena but in some cases come to the fore doing fine show in the images captured by us.
Several times in other articles I have talked about the thermal noise introduced by the photo sensor and how to deal with the problem (noise: tips to reduce it and the noise reduction in digital images) http://www.akusewa.com/sewa-backdrop-jakarta, but in addition to the noise you have to remember that there are two problems that can manifest itself : the so-called Hotpixel and Amp glow (the glow of amplification, if translated), using the term that identifies it.
The amplifier Glow is a phenomenon of electroluminescence. The read amplifier continuously generates heat (IR), the heat which in turn generates electrons on the pixel array of the CCD sensor (CMOS sensor is less affected by this problem). These electrons are going to add up the electrons that come from outside the photosites, distorting the real value.
Normally this phenomenon is seen in long exposure photographs (precisely because the amplifier is on for quite some time) and tends to be concentrated in a well defined area of ??the sensor (in the area closest to the amplifier). In the picture above, originally dark area in the upper left is very clear: the clear halo is precisely the amp glow (the photo should be uniform).
The only way to eliminate this defect is to turn off the read amplifier, which can not easily be done … and often can not be done and that’s it.
The amplifier, however, is not the only component of the circuitry to generate this phenomenon: it must also consider the camera battery (when supply current heats) and the protection circuit (or rather, the diode). If the first problem is related as is often mounted in a position far from the sensor, one can not say the same for the protective diode, often positioned in the vicinity of the sensor itself. These, like the amplifier, it can create a halo, making it even worse our image. In the picture below we can see the double halo, generated precisely as a buffer and protection diode. Again you can not do much to solve the problem, if not buy a camera “better” or that it was built taking into consideration the amp glow.