Black Level; Prnu (Pixel Response Non-Uniformity ) Correction - JAI LQ-401CL User Manual

6.2.6

Black level

The setup level of the LQ-400CL is set at 8LSB in 4 x 8-bit output mode as the factory default setting
(32LSB for 4 x 10-bit output mode)
In order to adjust, the following commands are available.
BLM= 0 Master mode
BLM= 1 Individual mode
BL= 0 to 64
BLR= -64 to 63
BLB= -64 to 63
BLIR= -64 to 63
If the gain is set at Master mode:
Adjusting range Master(green) : 0LSB to 64LSB (16LSB)

If the gain is set at Individual mode:
Adjusting range Red

6.2.7

PRNU (Pixel Response Non-Uniformity ) correction

PRNU (Pixel Response Non-Uniformity) is, as the name implies, a non-uniformity of the response of
each individual pixel. This means that for a fixed light level each pixel will have a slightly
different output level (response).
Before correction: Non-uniform response from pixel to pixel
Multiply
by
Factor < 1
Multiply
by
Factor > 1
To correct for PRNU, the camera's internal correction circuit captures one or several lines of data
under non-saturated illuminated conditions which are not more than 80% of maximum
(recommend level is half of maximum), and the average across the line is calculated. Based on
this average, coefficients are then generated for each individual pixel. The coefficient has the
function of multiplying the pixel output with a factor greater or less than 1. These coefficients are
stored in a non-volatile memory, and are therefore maintained after power down.
Red
Blue
NIR
Figures in ( ) are for 8-bit output
Green
Blue
NIR
Figures in ( ) are for 8-bit output
Note: Red, green, blue and NIR can be adjusted individually
Fig.15 Conceptual drawing for PRNU correction (1)
LQ-401CL
: -64(-16) LSB to +64(16) LSB
: -64(-16) LSB to +64(16) LSB
: -64(-16) LSB to +64(16) LSB
: 0LSB to 64(16) LSB
: 0LSB to 64(16) LSB
: 0LSB to 64(16) LSB
: 0LSB to 64(16) LSB
20
Max
Average
Min