18
Piranha2 User’s Manual
Test Pattern Pixels and End-of-line Sequence
To facilitate system-level debugging and verification of data path integrity, the camera
can generate a test pattern. The test pattern is a ramp from 0 to 255DN, then starts at 0
again. Use the test pattern to verify the proper timing and connections between the
camera and the frame grabber.
For information
on the test pattern
and end of line
sequence
commands, see
section
.
To alleviate post-processing, Piranha2 offers an end-of-line sequence that provides basic
calculations including "line counter", "line average", "pixels above threshold", "pixels
below threshold", and "derivative line sum". These basic calculations are the center of
most automatic gain control (AGC) algorithms.
To further aid in debugging and cable/data path integrity, the first six bits of the output
of the end-of-line sequence are "aa", "55", "aa". Refer to the table below.
Location Value
Description
1
A’s
2
5’s
3
A’s
By ensuring these values consistently toggle
between "aa" and "55", you can verify cabling
(i.e. no stuck bits)
4
4 bit counter LSB justified
Counter increments by 1. Use this value to
verify that every line is output
5
Line sum LSB
6
Line sum MID
7
Line sum MSB
Use these values to help calculate line
average
8 0
9
Pixels above threshold LSB
10
Pixels above threshold
MSB
11
Pixels below threshold LSB
12
Pixels below threshold
MSB
Monitor these values (either above or below
threshold) and adjust camera gain to keep
these values relatively constant. This
provides a basis for automatic gain control
(AGC)
13
Derivative line sum LSB
14
Derivative line sum Mid
15
Derivative line sum MSB
Use these values to focus the camera.
Generally, the greater the sum the greater the
image contrast
16
0
3.17
Generating Test
Patterns
03-32-00493-11
DALSA
