Lookup Table
Supported by...
All PixeLINK cameras support a 10-bit Lookup Table.
Description
The Lookup Table (LUT) typically has a number (typically 1024) of 2-byte
entries that range in value from 0 to 1023 (10-bit depth). The
LUT is used to implement the IIDC Gamma feature but it can also be used
to implement any LUT transfer function required.
The LUT is written to camera memory as a block of 1024 words at the
address specified by the Lookup Table Offset register, starting with Word
0 (Black).
When the LUT or Gamma function is active (ON), every pixel is converted
according to the transfer function stored in the LUT. With
both functions off, the LUT is bypassed and a linear transfer function
is used.
Since both Gamma and the LUT use the same camera memory, whichever function
was last turned on will control the memory and the other function will
be turned off. Turning
on the Gamma function will overwrite the LUT with the appropriate gamma
values.
Turning on the LUT will disable Gamma but will leave the camera memory
unchanged. If
the LUT is turned off, the LUT values will be retained in camera memory
and will be applied again once the LUT is turned on.
If the bit-depth of the camera is greater than that of the LUT, the
LUT output will be linearly interpolated.
API Control
PxLGetFeature,
PxLSetFeature
|
Feature
ID |
Number
of Parms |
Parameters |
Units |
Restrictions |
|
FEATURE_LOOKUP_TABLE
Lookup table control |
1
(See Note, below) |
fValue[MAX] |
N/A |
Integer only |
|
|
|
Note |
When using the PixeLINK API to access the Lookup Table
feature it behaves differently than all other features. When querying
the supported features of the camera using PxLGetCameraFeatures it will
return that FEATURE_LOOKUP_TABLE only has one parameter. The min and max
value of this parameter will be 0 and the maximum number of entries respectively.
When getting or setting the value of the lookup table using PxLGetFeature
or PxLSetFeature the number of parameters should be set to the maximum
number of entries and each parameter represents an entry in the lookup
table. |
|
|
|
Note |
The stream state must be off (STREAM_OFF) to modify
this feature. See
PxLSetStreamState.
For IIDC
programmers, see Transmitting
Video. |
Feature Flags
|
Camera |
Presence |
Read Only |
Auto |
Manual |
One-time Auto |
Off |
CiD |
|
All cameras |
Yes |
No |
No |
Yes |
No |
Yes |
No |
Parameters
|
Camera |
Parameter |
Unit |
Type |
Min |
Max |
Default |
Step Size |
Comments |
|
All cameras |
LUT |
None |
Absolute |
0 |
1024 |
N/A |
1 |
|
IIDC Control
Advanced CSRs
Information in this section is based
on the IIDC 1.31 specification. Please refer to the IIDC 1.31
specification for details on the meanings and use of CSRs.
The following table describes the Advanced Feature
CSRs that are allowed under the IIDC V1.31
specification as vendor specific. These CSRs are based at an offset
found in the Advanced Feature Offset value (register 0x480).
This table is common for all IIDC compliant PixeLINK
cameras. See the full table in the IIDC
Overview - Advanced CSRs topic.
|
Offset |
Name |
Field |
Bit |
Description |
|
ADVANCED FEATURE INQUIRY REGISTERS (READ ONLY) |
|
140h |
Lookup Tables Inquiry |
Presence_Inq |
[0] |
Presence of this feature |
|
In_Desc_Inq |
[1] |
Can this feature have different values in different
descriptors
1 = Yes, 0 = No |
|
|
[2..7] |
Reserved |
|
Bit_Depth |
[8..15] |
Bit depth of an entry in the lookup table |
|
Number |
[16..31] |
Number of entries in the lookup table |
|
144h |
Look Up Table |
Offset |
[0..31] |
Quadlet offset of the first entry in the lookup table.
Each entry occupies a whole number of bytes (e.g. a 10bit entry occupies
2 bytes). The table must be written to in order, starting from byte 0. |
|
ADVANCED FEATURE CONTROL REGISTERS |
|
214h |
Look Up Table |
On_Off |
[0] |
Lookup Table On/Off
1 = On, 0 = Off |
|
|
[1..31] |
Reserved |
