43results about How to "Guaranteed dynamic range" patented technology

A plurality of conversion characteristic functions 90, 92, and 94 used in a gamma correction circuit are stored in the processor in advance. A characteristic setting circuit sets standard characteristics 90 to the gamma correction circuit when exposure time E and a gain G are small. When E is large and G is small, change to correction characteristics 92 is made where inclination is set small at a low signal level, and amplification in a noise level at the low signal level is suppressed. When G is large, change to correction characteristics 94 having gentle inclination over a wider range than the characteristics 92 is made, and the amplification of the noise level that becomes larger in proportion to the G by gradation correction in the gamma correction circuit is suppressed.

The invention discloses a signal drift dynamic correction method and device. A direct-current recovery ring circuit is adopted for achieving dynamic correction of signal drift of photoelectric detector pre-circuit output, a signal amplification and conditioning circuit and the like, in the period of detecting a dark object, a switch S1 is closed, direct-current recovery is executed on a feedback loop, output is forced to reach a set low value, the switch S1 is disconnected to make direct-current recover a datum point A point level clamp, and a B point level is collected to serve as current background data; by switching to a scene target, an input scene target signal is overlaid on a direct-current level of the A point clamp, a B point level is collected to serve as the sum of scene targetdata and the background data, and scene target data can be obtained by subtracting the background data. The above-mentioned operations are repeated periodically, and the scene target data can be continuously obtained. Accordingly, the background signal level can be inhibited, the signal dynamic range can be widened, the system measurement precision is effectively improved, and the method and device are specially suitable for the technical field of space remote sensing.

Transition to the logarithmic range does not require the entire bit range of the result that is linearly dependent on the square of the value. Rather, for a value having x bits, the result can be scaled in such a manner that a representation with less than x bits of the result is sufficient to obtain the logarithmic representation based thereon. The effect of the scaling factor on the resulting logarithmic representation can be cancelled by adding a correction value obtained by using the logarithmic function on the scaling factor to or subtracting it from the scaled logarithmic function without dynamic loss. The invention provides a method and a device for producing a representation of a calculation result that is linearly dependent on the square of a value, thereby allowing to carry out the calculation easily or with little hardware.