ALLIED Vision Technologies Guppy F-503 - Manual (Page 155)

Description of the data path
GUPPY Technical Manual V7.1.0
155
Pixel operations in detail
The following diagrams show the principle of the pixel operations:
1. Exposure start: By starting the exposure the charge in the pixel is
flushed through a reset mechanism. Exposure starts and charge accumu-
lates in the pixel. At this time, the charge from the previous frame is on
the storage node and is being read out. The storage control is at 0 V.
2. Storage control gate open: When the previous frame’s charge is read
out of the storage node, the storage control gate is opened and the sat-
uration control gate is adjusted to level V1. Any charge that is already
accumulated above this level is spilled out to V
AA
.
3. Final steps: After time Shutter Width 1, the saturation control gate is
adjusted to level V2, thus allowing further charge to accumulate or spill
out if it exceeds the level set by V2. After time Shutter Width 2, the gate
is further adjusted to voltage level V3. Finally after time Total Shutter
Width, the storage control is closed. All the charge on the storage node
is isolated. This will be read out during the following frame integration
time.
Note

• Linear response causes loss of high-intensity detail in
the saturation region.
• Piece-wise linear response causes compression of high-
intensity detail (region after first and second knee
point). But there is an increased scene dynamic.
Figure 92: Details of pixel operations
Note

In the so-called auto knee-adjust mode Shutter Width 1+2
and Total Shutter are controlled automatically.
Storage
control Saturation
control
V
AA
Readout
0 V
0.5 V
2.5 V
3.3 V
Storage
control Saturation
control
V
AA
Readout
Any excess
charge is
0 V
0.5 V
2.5 V
3.3 V
Charge from
previous frame
Storage
control Saturation
control
V
AA
Readout
0 V
0.5 V
2.5 V
3.3 V
Storage
node
Storage
node
Storage
node
spilled out
V1
V2
V3
1. Exposure start 2. Storage control gate open 3. Final steps