National Instruments NI Vision NI 17xx User Manual

Also see for NI Vision NI 17 Series: User manual User manual

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National Instruments NI Vision NI 17xx User Manual Manual pdf 27 page image

Chapter 3 NI Smart Camera Image Sensor© National Instruments Corporation 3-3 NI 17xx Smart Camera User ManualImage Sensor Spectral ResponseThe spectral response curve describes the relative sensitivity of the sensorto different wavelengths of light. The peak responsiveness of the VGA andSXGA sensors is to light with a wavelength of approximately 500 nm.If you are imaging a dim scene, this information can be useful whenselecting a light source to use in your application as the camera is mostsensitive at its peak responsiveness. It also helps determine what, if any,filters your application might require to remove undesired wavelengths oflight from the scene.Refer to Appendix A, Specifications, to find the normalized spectralresponse curves for the VGA and SXGA sensors.Partial Scan ModePartial scan mode is a method of obtaining higher frame rates by readingout only a portion of the image from the sensor. Partial scan is frequentlyused when an application requires higher speed but less resolution than thesensor offers in full scan mode. The NI Smart Camera supports 1/2 scanand 1/4 scan. In 1/2 scan, shown in Figure 3-2b, one half of the image isread out from the center of the sensor and the rest of the image is discardedto enable a faster start of the next frame. In 1/4 scan, only one quarter of theimage is read out. Figure 3-2 illustrates the portion of the sensor exposedduring partial scanning.Figure 3-2. Partial Scan Modesa Full Scan b 1/2 Scan c 1/4 Scana b c