By default, the steps exposure and readout out of an image sensor are done one after the other. The pipelined CMOS sensors only support the overlapped mode. Even less CMOS sensors support the overlapped mode combined with trigger. Please check the sensor summary. In overlapping mode, the exposure starts the exposure time earlier during readout.

Figure 1: Overlapping / pipelined exposure and readout

CMOS sensors

The CMOS sensor modules incorporate the following features:

Sensors:	0.4 Mpixels resolution CMOS sensor (-200w / -0004Z)	1.3 Mpixels resolution CMOS sensor (-202a)	1.2 Mpixels resolution CMOS sensor (-x02v / -0012V)¹	1.2 Mpixels resolution CMOS sensor (-x02b)¹	1.2 Mpixels resolution CMOS sensor (-202d)¹	5.0 Mpixels resolution CMOS sensor (-205 / -0050Z)
Sensor supplier	Aptina	Aptina	Aptina	Aptina	Aptina	Aptina
Sensor name	MT9V034	MT9M001	AR0135	MT9M021	MT9M034	MT9P031
Resolution	752 x 480 gray scale or RGB Bayer mosaic	1280 x 1024 gray scale	1280 x 960 gray scale or RGB Bayer mosaic	1280 x 960 gray scale or RGB Bayer mosaic	1280 x 960 gray scale or RGB Bayer mosaic	2592 x 1944 gray scale or RGB Bayer mosaic
Indication of sensor category to be used	1/3"	1/2"	1/3"	1/3"	1/3"	1/2.5"
Pixel clock	40 MHz	40 MHz	40 MHz	40 MHz	40 MHz	40 MHz
Max. frames per second (in free-running full frame mode)	88.6²	24.6	24.6	24.6	24.4	5.8
Binning	H+V (frame rate 170 Hz)	H+V, AverageH+V (frame rate unchanged)	H+V, AverageH+V (frame rate unchanged)	H+V, AverageH+V (frame rate unchanged)	H+V, AverageH+V (frame rate unchanged)	H+V, 3H+3V, AverageH+V, Average3H+3V, DroppingH+V, Dropping3H+3V (frame rate 22.7 Hz)
Exposure time	10 us - 0.46 s	100 us - 10 s	10 us - 1 s	10 us - 1 s	10 us - 1 s	10 us - 10 s
ADC resolution	10 bit (10 / 8 bit transmission)	10 bit (10 / 8 bit transmission)	10 bit (10 / 8 bit transmission)	10 bit (10 / 8 bit transmission)	10 bit (10 / 8 bit transmission)	10 bit (10 / 8 bit transmission)
SNR		42 dB	40 dB	40 dB	< 43 dB	37.4 dB
DR (normal / HDR)	55 dB / > 110 dB	61 dB / -	> 61 dB /	> 61 dB /	> 61 dB / > 110 dB (with gray scale version)	65 dB /
Progressive scan sensor (no interlaced problems!)	X	X	X	X	X	X
Rolling shutter	-	X	-	-	X	X
Global shutter	X	-	X	X	-	X
Trigger (Hardware / Software)	X / X	X / -	X / -	X / -	X / -	X / X
Pipelined in continuous / triggered mode	X / -	X / -	X / -	X / -	X / -	X / - (reset only)
High color reproductivity (for color version)	X	no	no	no	no	no
Programmable readout timing with free capture windows and partial scan	X	X	X	X	X	X
Flash control output, synchronous to exposure period	X	no	no	no	no	no
More specific data	-200w / -0004Z	-202a	-x02v / -0012V	-x02b	-202d	-205 / -0050Z

¹ The operation in device specific AEC/AGC mode is limited in (non continuous) triggered modes. AEC/AGC only works while trigger signal is active. When the trigger signal is removed AEC/AGC stops and gain and exposure will be set to a static value. This is due to a limitation of the sensor chip.
² Frame rate increase with reduced AOI width, but only when width >= 560 pixels, below frame rate remains unchanged.

Note: For further information about rolling shutter, please have a look at the practical report about rolling shutter on our website: https://www.balluff.com/de-en/whitepapers/cmos-sensors-with-rolling-shutter; For further information about image errors of image sensors, please have a look at; For further information about image errors of image sensors, please have a look at Correcting image errors of a sensor.

Output sequence of color sensors (RGB Bayer)

Figure 2: Output sequence of RAW data

Bilinear interpolation of color sensors (RGB Bayer)

For Bayer demosaicing in the camera, we use bilinear interpolation:

Figure 3: Bilinear interpolation

Interpolation of green pixels: the average of the upper, lower, left and right pixel values is assigned as the G value of the interpolated pixel.
For example:

          (G3+G7+G9+G13)
G8     =  --------------
                4

For G7:

                            (G1+G3+G11+G13)
G7_new =  0.5 * G7 + 0.5 *  ---------------
                                   4

Interpolation of red/blue pixels:
Interpolation of a red/blue pixel at a green position: the average of two adjacent pixel values in corresponding color is assigned to the interpolated pixel.
For example:
```
         (B6+B8)           (R2+R12)
B7     = ------- ; R7    = --------
            2                 2
```
Interpolation of a red/blue pixel at a blue/red position: the average of four adjacent diagonal pixel values is assigned to the interpolated pixel.
For example:
```
         (R2+R4+R12+R14)             (B6+B8+B16+B18)
R8     = --------------- ;  B12    = ---------------
               4                           4
```

Any colored edge which might appear is due to Bayer false color artifacts.

Note: There are more advanced and adaptive methods (like edge sensitive ones) available if the host is doing this debayering.

Table of Contents

CMOS sensors

Output sequence of color sensors (RGB Bayer)

Bilinear interpolation of color sensors (RGB Bayer)