7 Parameters of Image Processing
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The
bad pixel correction
uses up to six non-false neighbour pixels to determine an interpolated value
from the neighbour pixels that replaces the bad pixel. In this way the image appears without disturbing
“hot” or “cold” pixels.
As the temperature of the camera itself directly influences the output data, for stable measurements it
is necessary to compensate this drift. Therefore the correction module
drift compensation
can be used.
It directly incorporates an internally measured temperature into a drift correction function.
The temperature characteristic curve of the microbolometer sensor usually is not linear. With help of
the
LUT
there is the possibility to linearize the data at the end of the processing chain, so that more
precise temperature values are resulting.
Ex factory camera specific correction data for each correction module are determined and stored in the
camera so that an optimum image quality is available at the Gigabit Ethernet interface. A PC with a
Gigabit Ethernet interface can transmit the temperature data directly to the main memory or rather to
the display. To reach more exact temperature measurements only an emission factor correction
depending on the surface and material of the object as well as of the environment temperature within
the object scene is necessary at the receiving end.
In case of high quality requirements with regard to exactness and image quality it is recommended to
determinate ex factory more than one correction data set by means of which some influence caused by
changing operating conditions of the camera are mostly compensated. Several different correction sets
for the two point correction are stored inside the camera. By transmitting commands over the serial
interface the user is able to activate (manually or automatically) the correction set which is most
suitable for the actual environment conditions of the camera.
7.2
File System
The IRC-320 camera models are equipped with a non-volatile data memory (64MByte flash) which
records configuration and correction data. Due to resource reasons the data is managed in a minimalist
file system. Because of this there are some restrictions briefly listed as follows:
•
Files are identified via one byte. Regarding to its function this file number is somewhat
comparable to the file name (including extension) from the PC-world. Valid file numbers are
between 1 (0x01) and 254 (0xFE).
•
The file type can be defined via a further byte. It is an optional clustering feature for files, but
it has no relevance for the file identification.
•
There is no directory structure. All files are on one single hierarchy level within the main
directory. This results in a maximum possible number of 254 simultaneously stored files,
because each file number can only be allocated once.
Ex factory the camera is usually already equipped with several files, containing system and correction
data. The IRC-320 don’t use the whole 64MByte, so that a customer can also use this memory for own
data. Refer to chapter 10.10 “Upload a File to Flash (
VDS Vosskühler GmbH
IRC-320