3. Installation
Contents
1. E n n if dc1394 stop iso transmission handle camera node DC1394 SUCCI printf couldn t stop the camera n save image as Image pgm imagefile fopen IMAGE FILE NAME w if imagefile NULL perror Can t create IMAGE FILE NAME dc1394 release camera handle amp camera dc1394 destroy handle handle exit 1 Adding the pgm file header fprintf imagefile P5 nsu su 255 n camera frame width camera frame height Writing to the file fwrite const char camera capture buffer 1 camera frame height camera frame width imagefile fclose imagefile printf wrote IMAGE FILE NAME n 25 Close camera dc1394 release camera handle amp camera dc1394 destroy handle handle return 0 In order to understand the code properly first understand the general structure of the program properly i Include the header files which means include lt libraw1394 raw1394 h gt lt libdc1394 dc1394_control h gt These are necessary in to access functions of the library Declare three variables of the following data types dc1394 cameracapture rawl394handle t nodeid t The rawi394handle t and nodeid t are required to uniquely identify the camera Moreover raw1394handle t is used to hold the handle that is created for the OHCI compliant host card 3 Open ohci and2. FRAMERATE 7 5 Frame rate amp camera dc1394 cameracapture type pointer DC1394 SUCCESS Our suggestion is that the various parameters should be first queried from the camera and then passed This is helpful in successful setup since often the user does not know actual values of the various parameters that 27 have to be passed in the setup function call and lands up in passing wrong values In such situations the setup is not done correctly and the camera doesn t get initialized We are listing the appropriate get functions that should be called first in order to obtain the correct values of the setup parameters e dc1394 get iso channel and speed handle camera nodes 0 amp channel amp speed to get the channel and the data speed e dc1394 get video format handle camera nodes 0 amp format to get the format e dc1394 get video framerate handle camera nodes 0 amp framerate to get the framerate e dc1394 get video mod handle camera nodes 0 amp mode to get the mode So the above dc1394 setup capture function call will look like dc1394 setup capture handle and camera nodes 0 uniquely identifies the camera handle camera nodes 0 we pass the variables instead of actual values channel format mode speed framerate amp camera dc1394 cameracapture type pointer DC1394 SUCCESS 7 Setting the trigger mode This is gener
3. cd libdc1394 1 1 0 examples make You can get programs exclusively written for the point grey cameras at http www ptgrey com support kb data grabdma tgz Fortunately we have an open source graphical application developed for the IEEE1394 cameras known as Coriander Coriander provides nice Graphical User Interface for libdc1394 which helps the user to work with the camera more efficiently We later discuss how Coriander helped us for debugging We briefly explain how to install Coriander Installation of Coriander Make sure that you have libdc1394 and Gnome libraries Coriander uses the gnome h installed on your Linux For more details regarding the requirements look into the user manual provided by the Coriander http damien douxchamps net ieee1394 coriander manual php Download the following tar file from sourceforge net coriander 1 0 1 tar gz Now proceed as shown below su root on O tar xvzf coriander 1 0 1 tar gz a O cd coriander 1 0 1 configure e cd src make make install Q run Coriander as cd coriander 1 0 1 coriander 1 0 1 src coriander Fortunately the installation of the libdc1394 and related modules is simple and does not pose any major problems Some minor problems you may face are due to mistake of not installing it as root or not changing the permissions of the newly created IEEE1394 devices 4 Concepts and Basic Programs At present the
4. handle camera_nodes 0 0 channel FORMAT VGA NONCOMPRESSED MODE 640x480 MONO SPEED 400 I FRAMERATE 7 5 amp camera DC1394 SUCC E n n fprintf stderr unable to setup camera n check line d of s to make sure n that the video mode framerate and format are n 23 supported by your camera n LINE FILE dc1394 release camera handle amp camera dc1394 destroy handle handle dc1394 free camera nodes camera nodes exit 1 dc1394 free camera nodes camera nodes set trigger mode LH e if dc1394 set trigger mode handle camera node TRIGGER MOD fprintf stderr unable to set camera trigger mode n fif 0 DC1394 SUCCESS dc1394 release camera handle amp camera dc1394 destroy handle handle exit 1 endif have the camera start sending us data if dc1394 start iso transmission handle camera node DC1394 SUCCESS fprintf stderr unable to start camera iso transmission n dc1394 release camera handle amp camera dc1394 destroy handle handle exit 1 capture one frame o if dc1394 single capture handle amp camera DC1394 SUCCESS 24 fprintf stderr unable to capture a frame n dc1394 release camera handle amp camera dc1394 destroy handle handle exit 1 Stop data transmission
5. the steps for the installation a su root b tar xvzf libraw1394 1 2 0 tar gz C cd libraw1394 1 2 0 d configure e make f make install 2 Installation of libdc1394 1 1 0 a su root b tar xvzf libdc1394 1 1 0 tar gz c cd libdc1394 1 1 0 d configure e cd libdc1394 f make x g make install step a has to be done only if you are not root 3 Installing the modules a modprobe ohci1394 b modprobe video 1394 c modprobe ieee1394 d modprobe raw1394 e smod to view that all the modules ieee1394 raw1394 ohci1394 video1394 are now installed Note The modules have got some dependencies ohci1394 gt video1394 ieee1394 video1394 ohci1394 raw1394 So if installing modules by insmod video1394 and raw1394 have to be installed first followed by ohci1394 and ieee1394 4 Create proper 1394 devices a cd dev mknod raw1394 c 1710 chmod 666 dev raw1394 d mkdir video1394 cd video1394 f mknod O0 c 171 16 g mknod 1 c 171 17 h chmod 666 dev video1394 Note Every time the system is restarted the nodes are destroyed and the modules are removed automatically So we wrote a script to automate this installation task at the startup to undo all the damage done during rebooting 5 su user 6 Check for the LD LIBRARY PATH It should contain usr local lib This is necessary to run the applications with the help of shared libdc1394 cotrol so 13 object file Note One can also set
6. RGB image Remember that size of RGB is 3 size of Bayer Pattern Image rgbbuffer is therefore assigned 3 times the buffer size camera capture buffer This buffer rgbbuffer will be passed as the destination buffer the second parameter in BayerNearestNeighbor After the buffer has been filled with the RGB values we write it in a file image rgb In order to view this image using gimp we need to append a bitmap header The method which we employed was 1 Save the RGB image buffer in a file say image ragb 2 Make a bitmap header and save it in a separate file bmpheader Refer http www fortunecity com skyscraper windows 364 bmpffrmt html for header details 3 cat bmpheader image rgb gt bmpfile 4 open bmpfile using gimp In order to run the program use the following steps g C conversions cpp g o grabcolor conversions o grabcolor cpp lrawl1394 l1dc1394 control Note There are many algorithms that are available in conversions cpp SO depending upon the requirement you can call the necessary functions The Coriander is useful in finding out how the RGB image would look like after undergoing different conversion algorithms For example it provides the choice between Nearest Neighbor Edge Sense Down Sample conversion algorithms The difference could be observed on a mouse click 43 4 5 Common Problems Faced While Working With IEEE1394 Cameras We now look at some of the common problems faced while work
7. assign a handle to it This is done by handle dc1394 create handle 0 Where handle is of raw1394handle t type The parameter O refers to the position of the camera on host card there may be more than one slot on the host card 0 means that the camera is on the first slot In case the wrong number is passed the handle will not be created 26 4 Get camera nodes There can be more than one camera nodes since IEEE1394 supports multiple devices on a single port But for our discussion we will assume that only a single camera is present Here is how to get nodes int numNodes raw1394 get nodecount rawl1394handle t handle camera nodes dc1394 getcamera nodes handle amp numCameras 1 If number of cameras returned is numcameras 1 Means no camera has been detected 1 in the function signifies that a printed description of the camera node found will be shown on the console 5 Check the condition camera nodes 0 numNodes 1 it must be false The explanation for this is out of scope of this document 6 Call the setup function and pass the various parameters For example Let us examine the setup function of the above example dc1394 setup capture handle and camera nodes 0 uniquely identifies the camera handle camera nodes 0 0 channel format of the Image FORMAT VGA NONCOMPRESSED MODE 640x480 MONO mode of the image SPEED 400 data speed
8. functions they don t call cetcameraControlRegister instead they call GetCameraFormat7Register 19 The following flowchart will make the differences evident Format query function call GetCameraFormat 7Register QueryFormat 7CSROffseti Fig 4 Flow of format query function call raw1394 read The format query function will call GetcameraFormat7Register which is supposed to read the values from the control and status registers of the camera This function in turn will call the queryFormat and CSROffset to know the offset for the particular information that has been queried After getting the offset the raw1394 read is used to actually read the values The format7 set functions also follow the same logic with the obvious difference that the reading functions are replaced by writing functions i e SetCameraFormat7Register and raw1394 write 4 1 6 Release Functions These are the final set of functions identified by us The basic job of these functions is to release the memory allocated to the capture buffer by the setup routine This is essential to save the system from memory leak These functions are defined in ac1394 capture c dc1394 release camera The function in turn calls free camera gt capture buffer which frees the memory Similarly the release function is available for DMA setup 20 4 2 Coriander A GUI for the libdc1394 Coriander helps in easy handling of the IEEE1394 cameras I
9. provided feature by the camera By feature we mean the characteristics of the camera yes rawl 94 write Fig2 Flow of set function call 4 1 3 Print Functions There are three print functions available 1 dc1394 print camera info This function is used to print the values stored in the dc1394camera info structure The print function is usually called after dc1394 get camera info to ensure that the dc1394camera info structure is not NULL dc1394 print feature This function is used to print the value of any feature It takes as an input pointer to dc1394 feature info structure 16 3 dc1394 print feature set This function is used to print the values of all features present in the camera It takes as an input pointer to dc1394 feature set Structure The function call basically calls dc1394 print feature repeatedly in a for loop 4 1 4 Setup Functions As the name suggests these functions are used to prepare the camera to start grabbing the images In order to setup the camera some parameters are to be passed to the function The number and the type of parameters are specific to the setup function But essentially three parameters are to be passed in all the setup X functions rawl394handle t nodeid t and pointer to dc1394 cameracapture structure this is to provide the buffer for grabbed the image and keep attributes like height of frame width of frame As mentioned previo
10. FeatureValue t GetCameraControlRegister i dci394 get camera info rawi394 read Fig1 Flow of get function call In case the get function you called is meant to retrieve value of a camera feature the value for the parameters listed in feature enumeration that get function calls another get function Getreaturevalue which takes the enumeration value of the feature as an input For example in case of gamma value the function passes 422 as the value this value can be calculated from the enumeration given in the dc1394 control h 13 Ultimately function GetCameraControlRegister whose task is to get the value from the appropriate control registers is called This functions takes the offset value octlet_t offset which is the offset from the base register as the input to its call The function prototype is declared in c1394 internal h GetCameraControlRegister rawl394handle t handle nodeid t node octlet t offset quadlet t value This will store the final result in the value Note The library makes use of typedefed data types octiet t quadlet t very frequently These are defined in c1394 internal h and stand for 8 byte and 4 byte data types The GetCameraControlRegister Will in turn call ac1394 get camera info to get the address of the base register camera ccr base CONFIG ROM BASE info ccr offset Once the base register and the offset is known raw1394 read is called by GetCame
11. Libdc1394 Library support for IEEE 1394 Cameras HOW TO Rohit Agarwal rohdimp 24 rediffmail com Vikram B vickys box rediffmail com Revision History Revision 1 0 1 15 October 2005 Revised by Vikram Minor bug fixes Revision 1 0 10 October 2005 Revised by Rohit amp Vikram Initial release Contents T EnitrOdU C HOT wpe crac tr cs nd at ates aes call ey se au ru aded UD opum ME 3 2 Requires bs ode co ord abeo Dex mut icda uota spesa rut Sumer Pest rac av Duc Da ES aT YU Uf 3 2c distal LOR eed etit aded t m tn Ces EI t MS eU DEP ME 3 A Concepts and Basic PRG STAINS oco ba orta tek o epa dde ra Eoo datio iS exeo Ei E E EV p Cu 9 A1 Types Of TUMCHONS merca me pro eee ERU Po tute Moen Ever Dyer rra arbo EV PE TRE EVER 12 2 13b Get Qu ry F nctionS coercet reo edi bu deret CIS UE CH AG Ve hA Te Rud 12 4 12 Set BUneHOBS sse co ree DO EPOR R A CREAR SEEN tare 15 4 15 Print F UNG el OMS sce despide ed ES nie dea oie usce dip Dm ord T 16 2 1 4 Setup EUHctioBs Sa Wd tede ta M epe ente iet eta 17 d ES Formaty PUDetotiss eoo de a ad M ted eq pint I te Ta NOR ID I E Dd 19 41 6 Release Functions ooi EAM DA a ona ha MM EI RI QE 20 4 2 Conander A GULTor the libaeL 394 3 5er ade atte dbia b aeg Ust xus 2 4 3 Example How to grab image from the IEEE1394 camera ssssesss 22 4 4 How to get color images Bayer Pattern Concepts sesssssseeee 31 4 4 1 Nearest Neighbor Algorthinis 5 eed rs e eroe ea reip c
12. Q van Eo Qe dag Rn 35 4 4 2 Example How to grab color image using IEEE1394 camera 36 4 5 Common Problems Faced While Working With IEEE1394 Cameras 44 DO RCT SRM CCG es aire epar ar a eta ioi iS E ace Ead ume ai 47 Appendix Jor anode tte op Matin tA ideas sardo leis pui ee A SAN tat vua 48 Wes ENCE R A EE E T EN 48 2 VISCIATINET EEEE EE 48 J ADO AUTOS ieina ut Ue P eur yaad e URN PN mtem REN EV aa Aa iaia ee anaa 49 4 NDCC AMOS coco as e I NUR NO Ker eae ale e UR ER 49 1 Introduction We felt how to on this topic is required since very little documentation is available for libdc1394 library Moreover the IEEE1394 cameras are gaining popularity which will lead to many people using this library to develop applications for cameras on Linux This how to is an outcome of our experience working with point grey dragonfly IEEE1394 camera on Linux We have given the overview of the library in a layman approach So anybody who has some programming experience can easily understand the contents We followed the following convention through out this document The function names and codes are in courier new while the text is in Arial We have used the library and libdc1394 interchangeably Similarly IEEE 1394 cameras cameras IEEE cameras are intended to mean the same 2 Requirements Various libraries and modules required are Library libdc1394 1 1 0 Supporting Library libraw1394 1 2 0
13. Supporting Modules ieee1394 raw1394 ohci1394 video1394 Linux Kernel 2 6 10 or above 3 Installation Prerequisite Make sure that the kernel is compiled with IEEE1394 built in support This is critical One can add support for the IEEE1394 devices by compiling the kernel again Don t panic here are the steps to compile the kernel 1 Go to the directory where the kernel source code is present Normally it is in usr src We would suggest that one should download a fresh copy of the kernel source code 2 6 10 from www kernel org Thus cd usr src kernel 2 6 10 Kernel 2 6 10 is the name of the source code directory It can vary from system to system 2 make menuconfig 3 The menu will come up Select Device Drivers 4 Device Drivers menu will come up Select IEEE1394 Firewire Support 5 Mark the following as M in the menu that is shown after step 4 e OHCI 1394 support e OHCI 1394 Video Support e OHCI 1394 DVI O Support e RAW Il EEE1394 I O Support 6 Press ESC to come out of the menu P Following steps are Save the configuration required to successfully install the library libdc1394 As a rule of thumb the installation has to be done as a root user 1 Installation of libraw1394 1 2 0 We had this library installed in our Linux so we skipped this step If you do not have this library inst alled make sure you install it before moving further Here are
14. all to get the value It is important to understand the utility of the above function call Refer to our discussion about the Bayer Pattern filters in the previous section We know that the pattern can be BGGR RGGB GRBG and GRBG The algorithm that we use for converting the Bayer pattern to RGB requires to know about the type of pattern the camera filter has got so that it can carry out some initialization refer tO conversions cpp for details The fourth parameter in the function call BayerNearestNeighbor src rgbBuffer camera frame width camera frame height pattern refers to this value BayerNearestNeighbor is the function call for the interpolation algorithm we discussed in the last section This is implemented in conversions cpp Having understood this we move on to the switch cases The value that is obtained for the Bayer Pattern qvalue is in the hex form which needs to be decoded for setting the value of variable pattern The case statements indicate the various hex values relating to Bayer Pattern that can be returned by the various cameras The intimidating values are actually quite easy to decode Here is the trick The hex code for various colors is as follows 42h gt B 47h gt G 52h gt R 42 Now if the ava1ue contains 0x42474752 it means B 42h G 47h G 47h R 52h or BGGR Similarly we can decode all the case statements Finally we need to declare another image buffer that will contain the
15. ally not required This is just like brightness dc1394 set trigger mode handle camera node TRIGGER MODE 0 sets the trigger mode to O 28 Note We have passed camera node which indicates that the dc1394 cameracapture structure is being used and only the particular node for which the camera has been setup is being referred to But we can as well use camera nodes 0 8 Have the camera start sending the data to the user This is done by starting the iso transmission The following function is used dc1394 start iso transmission handle camera node 9 Capture one frame by calling the function dc1394 single capture handle amp camera camera s a pointer to the structure dc1394 cameracapture This function will grab the image and store it in the buffer capture buffer provided by the structure In order to capture more than one frame use a for loop and place the function inside it for i20 i 100 it to capture 100 images dc1394 single capture handle amp camera 10 After the image has been grabbed stop the data transmission by calling the following function dc1394 stop iso transmission handle camera node 11 Add a PGM file header to the captured buffer to see the image using gimp 12 Use fwrite to save the captured image by writing the buffer camera capture buffer ina file The other parameters like height and width of the image can be extracted from the same structure camera frame
16. ays query for the values and then pass them to the function as explained in the example code in section 4 3 Problem 5 IDEO1394 IOC LISTEN CHANNEL ioctl failed Error message being displayed Sol This means that the DMA support is missing The error message is a good way to find out if the DMA support is available or not This can be done by using the setup functions that is meant for DMA support We at least found out this way Problem 6 Used ctrl c to terminate the image grabbing program Next time when run the camera program just hangs Sol The error occurs probably because the camera functions like a pipe and experiences a broken pipe situation if terminated without flushing the memory channels Trick is to disconnect the camera and connect it again One can also try debugging the problem installing the ohci1394 video1394 raw1394 video1394 modules again which works occasionally Problem 7 Every parameter is ok and the installation is also fine even then when the program is executed the camera is not detected 45 Sol This is a strange problem which we also face frequently The solution is based on hit and trial but it always works e Disconnect the camera first and then connect it again e Now run Coriander that s why we would suggest that one must install Coriander before start working with the camera e Make all the necessary adjustments i e select the mode of the camera the frame size etc e Close Coriand
17. d of s to make sure n that the video mode framerate and format are n supported by your camera n LINE FILE dc1394 release camera handle amp camera 38 dc1394 destroy handle handle dc1394 free camera nodes camera nodes exit 1 dc1394 free camera nodes camera nodes have the camera start sending us data if dc1394 start iso transmission handle camera node DC1394 SUCCESS fprintf stderr unable to start camera iso transmission n dc1394 release camera handle amp camera dc1394 destroy handle handle exit 1 capture one frame if dc1394 single capture handle amp camera DC1394 SUCCESS fprintf stderr unable to capture a frame n dc1394 release camera handle amp camera dc1394 destroy handle handle exit 1 query the camera to determine the Bayer pattern quadlet t qValue GetCameraControlRegister handle Camera nodes 0 0x1040 Bayer Tile Mapping register amp qValue bayer pattern t pattern BAYER PATTERN BGGR 39 switch qValue case 0x42474752 BGGR pattern BAYER PATTERN BGGR break case 0x47524247 GRBG pattern BAYER PATTERN GRBG break case 0x52474742 RGGB pattern BAYER PATTERN RGGB break case 0x47425247 GBRG pattern BAYER PATTERN GBRG break case 0x59595959 YYYY BW fprintf stderr Camera is black a
18. de a clear picture of which section of the code does what we have grouped the code lines together which perform a particular task and given a number which corresponds to the explanation bullet number For example the code section having number 1 means that user should see explanation point 1 for getting the details include stdio h include libraw1394 raw1394 h include libdc1394 dc1394 control h include lt stdlib h gt define IMAGE FILE NAME Image pgm int main int argc char argv FILE imagefile dc1394 cameracapture camera int numNodes int numCameras rawl394handle t handle nodeid t camera nodes Open ohci and asign handle to it handle dc1394 create handle 0 if handle NULL fprintf stderr Unable to aquire a raw1394 handle n n exit 1 22 get the camera nodes and describe them as we find them numNodes rawl1394 get nodecount handle camera nodes dc1394 get camera nodes handle amp numCameras 1 fflush stdout if numCameras lt 1 fprintf stderr no cameras found n dc1394 destroy handle handle exit 1 printf working with the first camera on the bus n if camera nodes 0 numNodes 1 fprintf stderr n Sorry your camera is the highest numbered node n dc1394 destroy handle handle dc1394 free camera nodes camera nodes exit 1 setup capture if dc1394 setup capture
19. documents that are available for understanding libdc1394 are very few Among the available documents are a FAQ 1 which talks about general concept of the camera and few forums where people have posted their queries We had to read the libdc1394 source code to understand how to grab a frame from the camera The extreme need of a complete explanation on this topic encouraged us to write this how to On the basis of what we understood by exploring the source code of the camera we are presenting an insight of the library We encourage you to keep referring following files while reading through the next section 1 dc1394 control h dc1394 control c 2 3 dc1394 capture c 4 dc1394 format7 c dc1394 control h is the most important file as it contains the declaration of various functions and data structures It should be read to understand the features supported by IEEE1394 cameras and the functions which access and control various features of camera The dc1394 library works closely with raw1394 since all the functions make use of functions of raw1394 raw1394 read and raw1394 write in order to retrieve or modify the values of various parameters of the camera This is one of the reasons why raw1394 must be installed before installing libdc1394 To understand how the functions provided by the library work we need to understand few technical aspects of the IEEE1394 camera 1 There can be more than one camera
20. e 0 if handle NULL fprintf stderr Unable to aquire a raw1394 handle n n Please check n if the kernel modules ieeel394 raw1394 and ohcil394 are loaded Wn if you have read write access to dev raw1394 n n exit 1 get the camera nodes and describe them as we find them ud numNodes rawl1394 get nodecount handle camera nodes dc1394 get camera nodes handle amp numCameras 1 fflush stdout if numCameras lt 1 fprintf stderr no cameras found n dc1394 destroy handle handle exit 1 printf working with the first camera on the bus n if camera nodes 0 numNodes 1 37 fprintf stderr An Sorry your camera is the highest numbered nodeWMn dc1394 destroy handle handle dc1394 free camera nodes camera nodes exit 1 obtain the values of the parameter from the camera dc1394 get video mode handle camera nodes 0 unsigned int amp mode dc1394 get iso channel and speed handle camera nodes 0 unsigned int amp channel unsigned int amp speed dc1394 query format7 byte per packet handle camera nodes 0 unsigned mode amp bytes per packet setup capture if dc1394 setup format7 capture handle camera nodes 0 channel channel mode speed bytes per packet 0 0 960 720 amp camera DC1394 SUCC El n n fprintf stderr unable to setup camera n check line
21. ed Image is grabbed using IEEE1394 Camera Now that we have presented the basic concept of the RAW RGB and the conversion algorithm we feel that you can understand example program that gives us a colored image We have chosen the format as format because the camera we used responds to this format only We will make use of another example code which provides the implementation of the algorithms The program is conversions cpp that is available in the grabdma folder You can download the grabdma folder from http www ptgrey com support kb data grabdma tgz To run the code make sure that you have the following files conversions h conversions cpp grabcolor cpp has also been taken from the grabdma folder We have modified the code according to our requirements and removed some of the lines Since most of the code is same as the previously discussed code we have explained only the portions that are different These portions have been made bold include lt stdio h gt include libraw1394 raw1394 h include libdc1394 dc1394 control h include stdlib h include conversions h define IMAGE Image rgb int main int argc char argv 36 FILE imagefile dc1394 cameracapture camera int numNodes int numCameras rawl394handle t handle nodeid t camera nodes int channel speed mode bytes per packet Open ohci and asign handle to it handle dc1394 create handl
22. er e Execute your program Bingo It works Note The first step is critical since we experienced a error message from the Coriander that it could not find the camera if we did not disconnected and connected back the camera before running Coriander 46 5 References 1 a A O N http kauri auck irl cri nz johanns libdc1394 libdc1394_FAQ html libdc1394 FAQ by Johann Schoonees http www ptgrey com http www ise stanford edu tingchen http damien douxchamps net ieee1394 coriander manual php Point Grey Dragonfly Camera Technical Reference Manual Version 2 1 2 1 5 Raw Capture A Second Chance to Get it Right Charlotte K Lowrie Sept 1 2005 http www linuxfocus org http www fortunecity com skyscraper windows 364 bmpffrmt html 47 Appendix A 1 License This document Libdc1394 Library support for IEEE 1394 Cameras How to is copyrighted c 2005 by Rohit Agarwal amp Vikram B Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation with no Invariant Sections with no Front Cover Texts and with no Back Cover Texts A copy of the license is available at http www gnu org copyleft fdl html 2 Disclaimer Although we have tried to do our best to bring out this how to in a good form we are not responsible for any damage due to the action
23. es per packet which depends on the mode e The value of left top can be set to QUERY FROM CAMERA Or can be specified directly by the user e The value of the width and height depends on what is the size of frame the user wants for eg if one wants 960x720 then pass 960 as width and 720 as height 4 4 How to get color images Bayer Pattern Concepts The image grabbed by the sample code in the previous section is not colored we have intentionally used the word not colored since the image is not gray scale either It is actually Bayer Pattern We will give an overview of Bayer Pattern and how they are used to get a colored image in this section Digital cameras use a solid state device called an image sensor These fingernail sized silicon chips contain millions of photosensitive diodes called photosites When you take a picture with a digital camera the intensity of light hitting each photo site on the sensor is recorded as a signal Depending on the camera either 12 or 14 bits of data are recorded At 12 bits the camera can record 4 096 levels of brightness At 14 bits the camera can record 16 384 levels of brightness This is referred to as bit depth The higher the bit depth the finer is the detail the smoother the transition between tones and the higher the dynamic range the ability of the camera to hold detail in both highlight and shadow areas But at capture digital images are grayscale not color To record color informa
24. ge the Bayer Pattern image is converted to RGB image A RGB image is an enhanced version of Bayer Pattern Image we try to find the value of the two missing colors at each pixel Remember that each pixel of the sensor is covered by Bayer Pattern Filter so we get a single color at any pixel by default This is done by using different algorithms like Nearest Neighbor Edge Sense etc m T8 7 EN a RAW RGB Where the shaded values are to be calculated by the algorithm Subscript denotes the tile on the Bayer Pattern to which the Value of R G and B belongs Note that the image size will become 3 times the Bayer Pattern Now in order to 33 view the RGB image we convert it to Bit Map or BMP image by adding a bitmap header To get the clear picture what is happening we have provided the following diagram IEEE1394 Camera MIT Alzonthm Bayer Pattem Image BGGR or RGGB or GRBG or GBRG PGM header Bayer Pattem Filter Without Bayer Pattern Filter i e if we remove the filter from the camera RGB Image Sensor Gray scale that cannot be converted to colored image Bitmap Header that s why we need a filter PGM Image Hence we needto consider the other path i e when the filter is present without colors Colored Bitmap Image Fig 5 Flow of conversion from Bayer Pattern to Bitmap Let s understand how the RAW to RGB conversion algorithms work We will look into detail the Nea
25. ing with the camera We have listed only those problems which we faced while using the camera These problems are likely to be faced by anyone who uses the library and the camera Some of the problems were solved with a proper reasoning but some were just hit and trial attempts We list down the problems and there solutions Problem 1 After the installation of the library and the modules the camera did not respond Sol We disconnected the camera and connected it again May be this has to be repeated multiple times We could not figure out an appropriate reason for this but it works Problem 2 Program is not compiling Sol If one forgets to link the executable with raw1394 and dc1394 control the program won t compile Correct way is gcc o xx xx c Iraw1394 1dc1394 control for C files g o xx xx cpp lraw1394 Idc1394 control for Cpp files Problem 3 Compilation failed giving the error ltbdocl394 control so l3 cannot open the shared object file Sol Check for the environment variable LD LIBRARY PATH This should contain the path of the shares library On our system the path was usr local lib So the path must be set accordingly 44 Problem 4 Program when executed hangs Sol This primarily happens if the values of parameters that are passed to the setup function are not supported by the camera For e g setting the mode mode 640x480 MONO I6 when it is not supported Our suggestion is that one should alw
26. low of Setup Function call 18 As shown in figure 3 the setup function in turn calls various set functions to set the parameter values to the camera registers In case of DMA setup after the set functions have been called the ioctl system call is called to set the DMA buffers The ioctl system calls will fail if the DMA is not supported by the camera and in such case you get the error message IDEO1394 IOC LISTEN CHANNEL ioctl failed The setup functions also allocate memory for the camera capture buffer camera capture buffer int malloc camera gt quadlets per frame 4 4 1 5 Format7 Functions These functions are used only if the camera is set for format7 This format is preferred since this allows the user to define the size of the image to be captured according to his need By default the size is 1024x768 you can set it to different dimension say 960x720 All format7 functions have format7 in their function names and the functions have been defined in a separate file dc1394 format7 c The setup function for format7 has a minor difference from the normal setup since it also asks for the size of the frame while you don t have to pass the format parameter as the setup function is meant only for a particular format i e format7 The function call flow remains the same as discussed in the previous section The format get functions are called query functions The mechanism is different from the normal get query
27. nd white n cleanup return 1 default fprintf stderr Camera BAYER_TILE MAPPING register unexpected value n tOx x n qValue return 1 int bufferSize camera frame width camera frame height assign a buffer of size three time the original image unsigned char unsigned char src unsigned char camera capture buffer unsigned char captureBuffer unsigned char camera capture buffer for int i 0 i lt bufferSize i src i captureBuffer i bytesPerPixel 40 rgbBuffer new unsigned char 3 bufferSize has an convert to color image BayerNearestNeighbor src rgbBuffer camera frame width camera frame height pattern Stop data transmission if dc1394 stop iso transmission handle camera node DC1394 SUCC printf couldn t stop the camera Nn save image as Image rgb without adding any pgm header printf Saving the image n imagefile fopen IMAGE w fwrite rgbBuffer 3 bufferSize imagefile fclose imagefile Close camera dc1394 release camera handle amp camera dc1394 destroy handle handle return 0 41 Gl As we have already discussed the use of cetcameraControlRegister YOU can understand that it has been used to find out the value contained at 0x1040 libdc1394 does not provide any function to query this address so we explicitly used this c
28. ntrol h We would like to mention one important aspect of the dc1394_control h file It lists out the values that can be set for the data speeds framerates camera modes image formats All the values are in the form of enumerations to help you write readable code For example enumeration for speed indicates that the data speed can be set only as 100 200 400 800 1600 or 3200 dc1394 control h lists the features brightness hue sharpness saturation etc supported for your camera Important Data Structures The library provides some structures which are useful in storing camera and image related information They have been declared in the file dc1394 control h Structure Use dc1394 camerainfo Helps in accessing the information about the camera model vendor ccr offset used to access the registers dc1394 cameracadpture Contains various parameters that are to be manipulated while the camera setup It also declares a buffer of int type that will be used to store the grabbed frame dol394 masc intro It contains the information about the iso channel id iso channel speed memory channel number 11 dc1394 feature info Contains the information about a particular feature brightness hue gamma white balance etc for example availability of a particular feature value for that feature etc We will be largely concerned about the dc1394 cameracapture str
29. raControlRegister to read the actual values Now the get function dc1394 get gamma use the value returned by the GetCameraControlRegister to modify the parameter gamma int dcl1394 get gamma rawl394handle t handle node t node unsigned int gamma In this way the user obtains the value of the camera parameter he queried for 14 4 1 2 Set Functions These functions are used to set the values of various camera features There is a corresponding set function for almost each get function You can recognize these functions by searching for set string For example dc1394 set gamma rawl394handle t handle nodeid t node int gamma Like the get functions this function needs raw1394handle t and nodeia t for camera identification The other parameter gamma is the user specified value for the gamma parameter The flow of the function call will be quite helpful in understanding what is actually happening The flow is exactly same as that of the get function Only difference is this time all the intermediate functions are also set functions and instead of rawl394 read it uses raw1394 write to write the value of the camera parameter on to the registers 15 dci394 set camera infoi Get function call for eg dc1394 set gamma listed in feature enumeration in dc13904 controlh SetFeatureValue SetCameraControlRegisteri No c gt in case the set function is about If setting the value of a feature
30. rest Neighbor algorithm Other Algorithms are explained in good detail in the following web link http www ise stanford edu tingchen main htm Most these algorithms make use of some kind of interpolations 34 4 4 1 Nearest Neighbor Algorithm In this interpolation method each interpolated output pixel is assigned the value of the nearest pixel in the input image The nearest neighbor can be any one of the upper lower left or right pixels An example will make the logic clear We try to find the G values for the R B tiles for a 3x3 block shown as shaded region The blank squares either bear R value or B value We have not them just to make the figure easy to understand Here we assume the left neighboring pixel value is used to fill the missing ones The left hand side table shows the G values for the Bayer Pattern Image In order to find out the missing G values for the other squares that originally contains only R or B we have the following approach Find the nearest G Value square and copy the G value of that square onto the R B square This has been illustrated in the above figure The square next to G7 was containing either R or B value So to get Gg G value for square 8 we copied the G value of square 7 since it was the nearest so Gg G7 Similarly we filled the other non G value squares The same logic is applied when finding R and B values for the Green Squares 35 4 4 2 Example program to understand how the Color
31. s taken based upon the information contained in this document It is impossible to test the things under all the configurations so probably some of the hints given in this document may be incorrect and may not work on your system In case you find anything wrong let us know it first We will rewrite it as soon as possible This document is provided as is We put great effort into writing it as accurately as we could but you use the information contained in it at your own risk In no event shall we be liable for any damages resulting from the use of this work 48 3 About Authors Rohit Agarwal and Vikram B are pursuing their Masters Degree in IT from International Institute of Information Technology Bangalore India They can be contacted at rohdimp_24 rediffmail com lt Rohit gt vickys_box rediffmail com lt Vikram gt 4 Dedications We are grateful to all our friends for their support We would specially like to thank Chinmay Narayan our batch mate for his valuable advices We would like to dedicate this document to our Professor Mr S Nagrajan for he is the person who showed us the path to contribute to the open source community 49
32. t uses the above discussed functions and libraries and provides a GUI for them The main advantage of the Coriander is that it saves time that is wasted in camera setup Also Coriander shows only those features and attributes that are present on the camera and hence you can judge how useful the camera will be for his her application development Most important feature of Coriander is its ability to display the captured image at run time Coriander also allows the user to convert a BGGR image to RGB We will discuss in detail the meaning of these types of images in detail in later sections Some of the files that can be useful in understanding the functioning of the Coriander are ls thread 136 6 2 Camera c 3 main c The Coriander homepage contains an excellent user manual which can be useful in case of any difficulty http damien douxchamps net ieee 1394 coriander manual php Our use of Coriander was limited only to check if the camera was working properly and if the focus was proper We will give some more usage of the Coriander in later sections 2 4 3 Example How to grab image from the IEEE1394 camera In this section we will see how to write a small program to grab an image from the camera We have taken the program grab gray image c given in the examples in the library tar file We have removed some lines to increase the readability of the code We have provided the explanation for this code below In order to provi
33. that is connected to the host card at any time hence one need to uniquely identify the camera node 2 The camera has some control registers to set camera features 3 According to IEEE specifications the camera can grab images in different formats The image formats are defined by two parameters format and mode Five modes are defined a Format 0 contains low resolution mode up to 640x480 b Format 1 contains medium resolution modes 800x600 and 1024x768 c Format 2 contains mega pixel modes 1280x960 and 1600x1200 d Format 7 is the scalable image format With this one can change the image size color coding and other parameters It may be possible that a camera does not support some of the modes SO we need to be careful while the setup You use setup to set various parameters like data speed image mode framerate that are necessary to make the camera ready to grab the image We will shortly discuss setup functions 4 In order to set or get the values of the parameters features of the camera the library functions modify or read the register values 5 The camera can work with or without DMA Unfortunately our camera does not support DMA and hence we could not really exploit the functionality of DMA related functions We limit our discussion to non DMA functions 10 With the above background we begin our discussion about the various functions data structures and other miscellaneous features available in the dc1394 co
34. the path by adding usr local lib in etc Id so conf This completes the installation phase In order to make sure if the installation is correct connect the camera to the IEEE1394 card assuming that the IEEE1394 card is already installed on the system and just run testlibraw S testlibraw It tests for the presence of host card camera and other related parameters We have given below a typical output from testlibraw Successfully got handle current generation number 17 1 card s found nodes on bus 2 card name ohcil394 using first card found 2 nodes on bus local ID is 0 IRM is 1 doing transactions with custom tag handler trying to send read request to node 0 completed with value 0x23127bac trying to send read request to node 1 completed with value 0x60217dac using standard tag handler and synchronous calls trying to read from node 0 completed with value 0x04477dac trying to read from node 1 completed with value 0xd37380ac testing FCP monitoring on local node got fcp command from node 0 of 8 bytes 01 23 45 67 89 ab cd ef got fcp response from node 0 of 8 bytes 01 23 45 67 89 ab cd ef polling for leftover messages The library libdc1394 1 1 0 comes with some example programs which are very helpful in understanding how the programs are to be written There is a Makefile available in the examples folder of the library tar file You can compile the programs and execute
35. tion each pixel on the sensor is covered with a red green or blue filter with the colors alternating A common arrangement of color filters is the Bayer pattern array that alternates colors but that also uses twice as many green filters as red and blue Twice as many green filters are used because our eyes are more sensitive to green This pattern or sequence of filters can vary 31 but the widely adopted Bayer pattern which was invented at Kodak is a repeating 2x2 arrangement Each pixel has been made sensitive only to one color one spectral band A Typical Bayer Pattern will look like The tile or square pixel that is labeled B means this particular tile is sensitive only to Blue light and so on The Bayer patterns may be classified into 4 types depending on how we have arranged the colors The naming of the Bayer Pattern is done by taking a 2x2 matrix from the top most corner of the pattern and the colors being read in 0 0 0 1 1 0 1 1 order So for the above Bayer Pattern if we take the 2x2 matrix as 32 The pattern is therefore known as BGGR The other possible patterns are RGGB GRBG GBRG The image we obtained in the previous example was a Bayer pattern Image also known as RAW image This was stored in camera capture buffer In order to view what we have captured we convert this RAW image to PGM by adding a header look at the explanation point 11 of the previous section In order to get a colored ima
36. ucture 4 1 Types of functions We have categorized the functions provided by the library into 6 types The categorization is purely done on our own for the ease of discussion Each of these functions has been declared in dc1394 control h We suggest you to keep a copy of the file in hand while going through subsequent section Get Query Functions Set Functions Print Functions Setup Functions Format 7 Functions Qr obe om acces Release Functions 4 1 1 Get Query Functions These functions are used to get the value of various features of the camera the information about the iso channel trigger mode frame rate format and mode These functions contain string get or query in their names For example int dc1394 get gamma rawl394handle t handle node t node unsigned int gamma This function gets value of the gamma attribute for camera 12 Most of the get functions take minimum of three parameters e rawl394handle t node t node these two together identify the camera e A pointer to obtain the value for example int gamma If we try to trace the flow of the function call we can understand what actually happens Get function call for eg dc1394 get gamma No gt in case the get query function is about If obtaining the value af a feature feature provided by the camera By feature we mean the characteristics of the camera yes listed in feature enumeration in dcl394 controlh Get
37. usly rawi394nandle t and nodeid t uniquely define the camera while pointer to c1394 cameracapture provides the buffer for the image frame to be grabbed It also stores information about the width and height of the frame which is useful at the time of image processing Other parameters that are passed are data speed frame rate image format image mode and iso channel number In case of camera using the DMA number of DMA buffers and drop frames is to be provided As we have already mentioned we will not be discussing about the DMA role in this text The various setup functions are dc1394 dma setup capture dc1394 setup capture dc1394 setup format7 capture BP W NY F dc1394 dma setup format7 capture These setup functions have been defined in dc1394 capture c 17 The user has a choice while passing the values for the parameters like data speed format mode and channel Instead of providing the value himself he may instruct the function to take the value from the camera This can be done by passing QUERY FROM CAMERA in place of the actual value for that function parameter The basic flow of control is easy to understand Setup function Call the set the setup function that functions related to uses DMA various parameters that have been passed Call the set functions related to various parameters that have been passed Call ioctl system call to set buffers and listen to the channel Fig 3 F
38. width camera frame height 13 Close the camera This step is necessary to save from the memory leak 29 dc1394 release camera handle amp camera dc1394 destroy handle handle In order to compile the program use gcc o grabImage grabImage c 1dc1394 control lraw1394 where grabImage c S your program We hope that after going through this algorithmic way of explanation you can comfortably understand the example code In case we used format image format we have to change only the setup capture function Let us look at the setup function dc1394 setup format 7 capture handle and camera nodes 0 uniquely identifies the camera handle camera nodes 0 channel channel mode mode bytes per packet left area of interest start column right area of interest start row width area of interest width height area of interest height amp camera dc1394 cameracapture type pointer DC1394 SUCCESS where the values of the parameters channel speed bytes per packet speed mode are found using the following functions e dc1394 get iso channel and speed handle camera nodes 0 amp channel amp speed to get the channel and the data speed e dc1394 get video mod handle camera_nodes 0 amp mode to get the mode 30 e dc1394 query format 7 byte per packet handle camera nodes 0 mode amp bytes per packet l to get the byt
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