JAI LT-200CL User Manual

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JAI LT-200CL User Manual Manual pdf 20 page image

LT-200CL19The following drawing shows the characteristics of Knee Point 890LSB and Knee Slope1000h.Output Camera Link Data Level102389000 4095Input Data Level2848Knee Point = 37Ah (890)Knee Slope = 1000h (1/16)In this case : Maximum Value is 968 LSB.968[100%]32[0%]Knee Point12791021/16Fig.19 Knee and knee slope characteristics6.3.10 PRNU (Pixel Response Non-Uniformity ) correctionPRNU (Pixel Response Non-Uniformity) is, as the name implies, a non-uniformity of theresponse of each individual pixel. This means that for a fixed light level each pixel willhave a slightly different output level (response).Fig.20 Conceptual drawing for PRNU correction (1)To correct for PRNU, the camera‟s internal correction circuit captures one or severallines of data under non-saturated illuminated conditions which are not more than 80% ofmaximum (recommend level is half of maximum), and the average across the line iscalculated. Based on this average, coefficients are then generated for each individualpixel. The coefficient has the function of multiplying the pixel output with a factorgreater or less than 1. These coefficients are stored in a non-volatile memory, and aretherefore maintained after power down.Fig.21 Conceptual drawing for PRNU correction (2)MaxMinMultiplybyFactor > 1MultiplybyFactor < 1Before correction: Non-uniform response from pixel to pixelAverageAfter correction: flat response from pixel to pixelAverage