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7 Parameters of Image Processing

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7

Parameters of Image Processing

This chapter explains the function of the IRC-320 firmware. It is related to the individual modules of
image processing and shows in what way the user can control these modules via the serial Interface.

7.1

Image Processing Chain

Due to the fact that the uncorrected sensor image from the microbolometer sensor is very
inhomogeneous and that each sensor element has its own characteristic curve, an individual
adjustment of each pixel is necessary. The standard firmware of the IRC-320 contains a chain of
correction modules which undertake these tasks in real time.

LUT

Integrator /

Image Store

Two Point

Correction

Bad Pixel

Correction

Drift

Compensation

Output

(CL, GigE)

Input

(Camera

Raw Data)

E,J,K,N

F

m,n,o,p

H

Correction Data

Memory Access Module

S

(C)

(A,B)

(H/U,A,B)

(H/U)

Flash Memory

Access Module

A,B,C

Background

Subtr

Integrator /

Image Store

M,U

(U/H)

(U/H)

D,G

Each module can have various parameters which control the operation mode. In the sketch above and
as well within the text of this manual, these parameters are always marked by “

Courier

” font in

order to highlight them to be parameters (or commands) adjustable via the serial Interface.

For fast access all available correction data (e.g. reference images for the two point correction and bad
pixel correction control data) are copied from the non-volatile flash memory into a correction data
memory (SDRAM) when starting the camera. From this point the correction data is available for real-
time image correction. The image data from the camera head is shifted through the correction modules
and the corresponding correction data is applied. Some modules may also write new data back to the
correction memory – but currently only to the SDRAM and not to the non-volatile Flash memory.

The main correction modules are in detail:

1.

Two Point Correction

2.

Background Correction

3.

Bad Pixel Correction

4.

Drift Compensation

5.

Look Up Table (LUT)

With help of the

two point correction

(likewise “Gain Offset Correction”) the normally distinctive

underground structure of the microbolometer sensor can be equalized. The gain and the offset for each
pixel of the input image can be adapted to the set values on the basis of two reference images so that in
the optimum case no image structure is discernible.

The IRC-320 models feature an electromechanical shutter. In conjunction with the second correction
module in the chain – the

background correction

– the image quality can additionally be enhanced.

The shutter is closed to acquire a temporary background correction image. This image is subtracted
from the two point corrected image data to reduce the remaining fixed pattern noise.

VDS Vosskühler GmbH

IRC-320

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Содержание 1043452

Страница 1: ...is document may not in whole or in part be copied photocopied or otherwise reproduced without prior permission of the publisher This document may not in whole or in part be copied photocopied or otherwise reproduced without prior permission of the publisher Date March 2010 Date March 2010 Technical details are subject to change without notice Technical details are subject to change without notice ...

Страница 2: ...CC1 14 6 1 2 Timing FVAL LVAL DVAL PCLK 14 6 1 3 Output Data Specification 15 6 2 CONVERSION OF IMAGE DATA TO TEMPERATURE DATA 15 6 3 CONSIDERATION OF THE EMISSION RATIO 16 6 4 GIGABIT ETHERNET 16 7 PARAMETERS OF IMAGE PROCESSING 18 7 1 IMAGE PROCESSING CHAIN 18 7 2 FILE SYSTEM 19 8 INTRODUCTION TO THE TWO POINT CORRECTION A B E J K N 20 9 BASIC PARAMETERS AND COMMANDS 21 9 1 SELECT A CORRECTION D...

Страница 3: ...11 APPENDIX 32 11 1 COMMAND REFERENCE 32 12 DECLARATION OF CE CONFORMITY 40 13 REVISION HISTORY 41 ...

Страница 4: ...le lenses for LWIR with various focal lengths can be offered Also different temperature ranges are possible 1 1 Common Features 320 H x 240 V pixels Uncooled microbolometer sensor 8 14 µm LWIR spectral sensitivity Measurement temperature range of 20 C up to 80 C standard version Pixel size 35 µm x 35 µm 40 Hz frame rate 12 bit digital output with Gigabit Ethernet Built in mechanical shutter Prepro...

Страница 5: ...emperature sensor 25 C 45 C Storage temperature 30 C 70 C Humidity Operating and storage 10 to 95 RH non condensing Shock 25G Vibration 2G Interface Power supply 12V SELV 0 5 max 1 5A Digital interface Gigabit Ethernet 1000Base T Output data 12bit pixel Mechanical Dimension with 18mm F 1 0 134mm x 90mm x 86mm Weight with 18mm F 1 0 600g Housing material Aluminium alloy AlMgSi1 General CE conform s...

Страница 6: ...20 it is an advantage to operate the camera under constant ambient air temperature This can e g be facilitated by assembling the camera on a bigger metal corpus or by an additional active temperature regulation The red LED at the backside of the camera L3 or the value of the register T serves for examination If L3 permanently lights up or rather the lowest bit of T is set the camera housing has a ...

Страница 7: ...38 1 Ø45 7 62 94 101 max 32 7 max 28 9 15 27 3 2 Back View of the camera Power L2 L3 L4 L5 Power Control connection Gigabit Ethernet connection Ø90 UNC1 4 2x and M4 mounting holes are in the center of main body LED s at the Backside of the Housing L2 Camera is operational L3 Temperature state off temperature is OK Power Power state L4 Trigger reset input activity L5 Frame output VDS Vosskühler Gmb...

Страница 8: ...but the RS232 signals at the 15 pin D SUB jack may also be used To access it a serial terminal program employing the serial port of the user s Pleora iPORT software interface or a PC s RS 232 COM port is required For Gigabit Ethernet the Pleora iPORT documentation contains the corresponding information If the serial interface is routed over the 15 pin D SUB jack then e g HyperTerminal being part o...

Страница 9: ...returned There is an input buffer holding a few characters but no hardware handshake Thus a sequence of commands should not be send to the camera without awaiting the intermediate input prompts Otherwise the camera s serial input buffer may overflow 4 3 Adjust the Image Processing Subsequently the important commands for quick starting the image correction of the IRC 320 are mentioned All further p...

Страница 10: ...nsumed time by the command k 0 Description Time Max Time Typical time for a IRC 320 Close shutter optional 4 T 100ms 0ms Save one image 3 T 75ms 75ms Open shutter optional 0 T 0ms 0ms Choose data set N1 2 T 1600ms 800ms N1 16 Close shutter 5 T 125ms 125ms Integrate images N2 1 T 1625ms 1625ms Open shutter 0 T 0ms 0ms Calculate statistics 2 T 50ms 50ms At all 3 58s 2 68s T Time for one frame out IR...

Страница 11: ...terminal program e g HyperTerminal is sufficient for manually controlling the camera Please note that operating this serial interface and the second available port via Gigabit Ethernet interface concurrently may lead to unexpected results Both interfaces share the same receive buffer and thus the characters of simultaneously sent commands may be randomly mixed up See chapter 10 7 Baud Rate s for m...

Страница 12: ...temperature being too low results in a degradation of image quality and inexact temperature measurement In case that this control output will not become inactive after some minutes of operation the ambient air temperature of the camera might be too low A heat up of the camera should resolve this 5 6 Sensor Temperature too High Pin 14 Voltage Logical Level Description 0 8 V low Sensor temperature t...

Страница 13: ...ta bits While the base configuration is able to operate with one cable for the medium and the full configuration two cables between camera and grabber are necessary The transmission components apply the so called Channel Link technology 28 parallel data bits each are serialized in a ratio of 7 1 and transferred in connection with the clock signal via altogether five differential signal pairs By us...

Страница 14: ...on For this reason the internal clock frequency is artificially increased by factor four before being output as Camera Link clock signal As a consequence an unnecessary high data rate would occur at the grabber why a multiple of the really needed data volume ought to be moved within the storage of the receiver Now the DVAL signal offers the opportunity to explicitly mark particular data words as v...

Страница 15: ... D11 MSB B4 B5 B6 B7 C0 C1 C2 C3 C4 C5 C6 C7 6 2 Conversion of image data to temperature data Due to the internal LUT the pixel information can be converted to a corresponding temperature value For the IRC 320 the following relation can be used o DN r T with 12 bit Digital value Pixel data DN T Temperature value C r Resolution for the IRC 320 standard version 0 03 C offset for DN 0 for the IRC 320...

Страница 16: ...b T Background temperature in Kelvin ε Emission ratio Notes Normally the background temperature can be assumed to be equal to the environmental temperature The emission grades of many different materials can be found on various internet sources 6 4 Gigabit Ethernet The IRC 320 cameras are equipped with a 1000Base T Ethernet interface RJ 45 connector The data connection between camera and PC can be...

Страница 17: ...6 Data Interface 17 41 8 1 Front view of the Gigabit Ethernet jack Pin Signal 1 D1 2 D1 3 D2 4 D3 5 D3 6 D2 7 D4 8 D4 VDS Vosskühler GmbH IRC 320 ...

Страница 18: ...data e g reference images for the two point correction and bad pixel correction control data are copied from the non volatile flash memory into a correction data memory SDRAM when starting the camera From this point the correction data is available for real time image correction The image data from the camera head is shifted through the correction modules and the corresponding correction data is a...

Страница 19: ...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 w...

Страница 20: ...e determination By means of recording two reference images at the scene temperatures TA und TB the data samples can be determined for all pixels Furthermore the digital set values J and K each belonging to the temperatures TA and TB are determined Owing to the four parameters mentioned above the two point correction is now able to modify the gain and the offset of each pixel characteristic curve i...

Страница 21: ...x1A Both parameters A and B together affect the choice and the number of data sets to be loaded By means of the parameter S the address of the active page can be adjusted Example Activate the eleventh correction data set address 10 0xA S A CR 9 2 Automatic Calibration k Beside the manual selection of data sets with parameter S also an automatic calibration one time or timer controlled repeating ca...

Страница 22: ...eter sensor is outside the optimum range After switching on the cold camera this may take place for a time because the stabilization of the sensor temperature takes some minutes until the set value becomes achieved In case that the temperature warning remains active for a longer period the environment temperature of the camera should be checked For information about the starting procedure see chap...

Страница 23: ...data A from the input data In addition the set value J is added as offset to each pixel value 5 One point correction Simple subtraction of the correction data B from the input data In addition the set value K is added as offset to each pixel value Attention Operating modes 2 and 3 exist for test purposes In case of activating one of these modes it has to be taken into consideration that the module...

Страница 24: ...alues for all correction sets from this file are loaded when switching on the camera and stored back with X 1 In case that only one correction data set is on hand N can remain on the value zero because J and K only the values of the actual memory page are stored together with all other parameters of one system file apart from the file N Please note that changes to J and K can not be stored to file...

Страница 25: ... 9 8 7 6 5 4 3 2 1 0 c a b b b a U 0 Operation Mode Background Correction ro rw rw rw rw rw Bit group Value hex Explanation a 0 Output deactivated Data is passed through transparently 1 Output activated Apply the current correction image H U and offset value M 2 Output activated Output of current correction image H U b 0 Integration deactivated The image store content is not changed 1 Integration ...

Страница 26: ...necessary The bad pixel correction applies up to six non false neighbour pixels in order to determine an interpolated value from the neighbour ship At the position of the defective pixel an interpolated value in exchange of the bad pixel value is output The parameter F controls the operation mode of the bad pixel correction The following value assignment is applied 0 Bad pixel correction deactivat...

Страница 27: ...represented in 16 bits fixed point two s complement notation An additional offset user offset can be specified by p p16 This parameter is represented in 16 bits fixed point two s complement notation 10 5 Look Up Table LUT D G The temperature data of the microbolometer sensor is generally not linear By means of the LUT there is the opportunity to linearize the data that have already been pre correc...

Страница 28: ...ast started integration is still running This bit can only be read out during write access to H it is ignored The table below illustrates the possible values for the individual bit groups F E D C B A 9 8 7 6 5 4 3 2 1 0 d c c b b b a H 0 Operation Mode Integrator Image Store ro rw rw rw rw rw rw Bit group Value hex Explanation a 0 Output deactivated Data are passed through transparently 1 Output a...

Страница 29: ...e and x Each bit group has a special function being independent of the other ones a Controls the configuration of the serial port e Controls the echo mode x Controls the baud rate of the serial port F E D C B A 9 8 7 6 5 4 3 2 1 0 e a a x x x x s 0 Operation Mode Integrator Image Store rw rw rw rw rw rw rw Bit group Value hex Explanation x O 110 Baud 1 300 Baud 2 600 Baud 3 1200 Baud 4 2400 Baud 5...

Страница 30: ... administrated by serial commands RS232 or Pleora Gigabit Ethernet There are different commands to control the file system l 1 List actually stored file numbers d p8 Delete the file with the specified file number v p8 View file Dumps all bytes of the specified file to the serial interface Q p8 Upload a file and store it in the Flash memory Warning The commands d p8 and Q p8 do not need additional ...

Страница 31: ... soon as the module outputs its command prompt the sender may retry the transmission If the transmission fails several times the flash chip may be full or there is an error in the hardware Warning Do not switch off the camera during file writing operation e g command d p8 or Q p8 until the host received the command prompt character Doing so will very likely corrupt the file system In this case the...

Страница 32: ...urred somewhere previous to the prompt a question mark character is displayed To query a parameter value send the corresponding command letter followed by the equality sign and a question mark character s CR If the intended action does not need any parameter it is also sufficient in most cases as a shortcut to send the command letter only directly followed by CR At the beginning of a command seque...

Страница 33: ...ce only See W p8 for details c Current shutter state Use I p8 to control the shutter IRC 320 IRC 600 only d NIR 300F support 0 Normal mode e g for IRC 300 320 600 NIR 300 1 NIR 300F mode e Destination for bad pixel correction data loading from flash NIR 300F 0 Buffer used during normal mode CC2 high 1 Buffer used during fast AOI mode CC2 low f The shutter s normal inactive state IRC 320 600 only 0...

Страница 34: ...20 600 only Close the mechanical shutter for background correction image integration e 0 Do not calculate new mean value 1 Calculate new mean value and set it as offset for the background correction M p16 f Operation mode during image integration See bit field b of parameter U p8 for description k p16 Start the automatic calibration function Depending on the value of j different correction mechani...

Страница 35: ...200 Baud a Second channel UART configuration This channel is equivalent to the main UART concerning the use as command interface But it is not intended to use both UARTs at the same time because they share the same receive buffer Output characters are always sent to both channels 00 Second channel UART off The active serial communication port is selected by hardware jumper settings 01 Activate sec...

Страница 36: ...ains uninitialized at startup 01 EF The correction data is loaded from the indicated file In case that the following number also exists within the flash it is loaded into a second page of the correction memory The actually data page for correction is selected depending on the grabber s CC2 signal state D p8 File number of the data for the 12 bits LUT Changing this parameter may void ex factory cal...

Страница 37: ...ntegrate 32 images and divide by 32 111 Integrate 64 images and divide by 64 Other values undefined c Control of the data copy process usually done after a new image has been integrated Let pass through at least one complete frame to be sure wait two frames from the camera to completely copy the data Set this field back to 00 after copying Notice that the set values J and K are not affected 00 No ...

Страница 38: ...the flash memory using the specified file number After issuing CR a special transfer protocol is processed A currently existing file will be overwritten S p8 Number of the correction data set to activate The range of valid values depends on the number of factory prepared and currently loaded data sets Please note that a change of S affects the correction data for the gain offset correction T 1 Sho...

Страница 39: ... by 8 101 Integrate 16 images and divide by 16 110 Integrate 32 images and divide by 32 111 Integrate 64 images and divide by 64 Other values undefined c State of the integration process read only 0 Integration has finished 1 Integration is still in progress V 1 Show firmware version and calibration data information W p8 Switch the destination of the opto coupler trigger input at pins 10 11 of the...

Страница 40: ...12 Declaration of CE Conformity 40 41 12 Declaration of CE Conformity VDS Vosskühler GmbH IRC 320 ...

Страница 41: ...13 Revision History 41 41 13 Revision History Revision Date Description 3 0 18 03 2010 Full Updated VDS Vosskühler GmbH IRC 320 ...

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