Image Acquisitionand Proces

Recommendations

Info

Setting Up 19 Linear Aray Light Source Prism/Grating A B C D A B C D FIGURE 2.6 Spectrometer schematic. A special member of the Line Scan family does not scan at all — the line detector. This type is often used when detecting intensity variations along one axis, for example, in a spectrometer (Figure 2.6). As the light diffracts through the prism, the phenomenon measured is the relative angular dispersion, thus a two-dimensional mapping is not required (although several such detectors actually use an array a few pixels high, and the adjacent values are averaged to determine the output for their perpendicular position of the array). 2.1.1.5 Camera Link A relatively new digital standard, Camera Link was developed by a standards committee of which National Instruments, Cognex and PULNiX are members. Camera Link was developed as a scientiÞc and industrial camera standard whereby users could purchase cameras and frame grabbers from different vendors and use them together with standard cabling. Camera Link beneÞts include smaller cable sizes (28 bits of data are transmitted across Þve wire pairs, decreasing connector sizes, therefore theoretically decreasing camera-housing sizes) and much higher data transmission rates (theoretically up to 2.38 Gbps). The Camera Link interface is based on Low Voltage Differential Signaling (LVDS), a high-speed, low-power, general purpose interface standard (ANSI/TIA/EIA-644). The actual communication uses differential signaling (which is less susceptible to noise — the standard allows for up to ± 1V in common mode noise to be present), with a nominal signal swing of 350 mV. This low signal swing decreases digital rise and fall times, thus increasing the theoretical throughput. LVDS uses current-mode drivers, which limit power consumption. There are currently three conÞgurations of Camera Link interface — Base, Medium and Full — each with increasing port widths. The Camera Link wiring standard contains several data lines, not only dedicated to image information, but also to camera control and serial communication (camera power is not supplied through the Camera Link cable). More information regarding the Camera Link standard can be found in the “SpeciÞcations of the Camera Link Interface Standard for Digital Cameras and Frame Grabbers” document on the accompanying CD-ROM.
20 <strong>Image</strong> Acquisition <strong>Proces</strong>sing with LabVIEW 2.1.1.6 Thermal Used primarily in defense, search and rescue and scientiÞc applications, thermal cameras allow us to “see” heat. Thermal cameras detect temperature changes due to the absorption of incident heat radiation. Secondary effects that can be used to measure these temperature ßuctuations include: Type Thermoelectric Thermoconductive Pyroelectric Description Two dissimilar metallic materials joined at two junctions generate a voltage between them that is proportional to the temperature difference. One junction is kept at a reference temperature, while the other is placed in the path of the incident radiation. A bolometer is an instrument that measures radiant energy by correlating the radiation-induced change in electrical resistance of a blackened metal foil with the amount of radiation absorbed. Such bolometers have been commercially embedded into arrays, creating thermal image detectors that do not require internal cooling. Pyroelectric materials are permanently electrically polarized, and changes in incident heat radiation levels alter the surface charges of these materials. Such detectors lose their pyroelectric behavior if subject to temperatures above a certain level (the Curie temperature). Thermal cameras can be connected to National Instruments image acquisition hardware with the same conÞguration as visible spectrum cameras. More information regarding thermal cameras can be found at the FLIR Systems Web site (http://www.ßir.com). IndigoSystems also provides a large range of off-the-shelf and custom thermal cameras that ship with native LabVIEW drivers. More information on their products can be found at http://www.indigosystems.com. 2.1.2 CAMERA ADVISORS: WEB-BASED RESOURCES Cameras come in all shapes, sizes and types; choosing one right for your application can often be overwhelming. National Instruments provides an excellent online service called “Camera Advisor” at http://www.ni.com (Figure 2.7). Using this Web page, you can search and compare National Instruments tested and approved cameras by manufacturer, model, vendor, and speciÞcations. There is also a link to a list of National Instruments tested and approved cameras from the “Camera Advisor” page. Although the performance of these cameras is almost guaranteed to function with your NI-IMAQ hardware, you certainly do not have to use one from the list. As long as the speciÞcations and performance of your selected camera is compatible with your hardware, all should be well. Another excellent resource for cameras and lenses system is the Graftek Web site (http://www.graftek.com; Figure 2.8). Graftek supplies cameras with NI-IMAQ drivers, so using their hardware with the LabVIEW Vision Toolkit is very simple. The Graftek Web site also allows comparisons between compatible products to be made easily, suggesting alternative hardware options to suit almost every vision system need
Page 3: IMAGE PROCESSING SERIES Series Edit
Page 6: Foreword The introduction of LabVIE
Page 9 and 10: FIGURE 1 Vision 6.1 FIGURE 2 Compan
Page 12 and 13: Acknowledgments My gratitude goes o
Page 14: Dedication To Don “old fella” P
Page 18 and 19: Contents Chapter 1 Image Types and
Page 20 and 21: Chapter 4 Displaying Images........
Page 22 and 23: Chapter 7 Image Analysis...........
Page 24 and 25: 1 Image Types and File Management F
Page 26 and 27: Image Types and File Management 3 F
Page 28 and 29: Image Types and File Management 5 A
Page 30 and 31: Image Types and File Management 7 C
Page 32 and 33: Image Types and File Management 9 p
Page 34 and 35: Image Types and File Management 11
Page 36 and 37: Image Types and File Management 13
Page 38 and 39: 2 Setting Up You should never under
Page 40 and 41: Setting Up 17 FIGURE 2.3 (a) Interl
Page 44 and 45: Setting Up 21 FIGURE 2.7 National I
Page 46 and 47: Setting Up 23 2.1.3.2 Control and I
Page 48 and 49: Setting Up 25 FIGURE 2.11 X-Ray ima
Page 50 and 51: Setting Up 27 Apple Computer techno
Page 52 and 53: Setting Up 29 FIGURE 2.17 An inexpe
Page 54 and 55: Setting Up 31 Although this would b
Page 56 and 57: Setting Up 33 134 -115 \ Contrast =
Page 58 and 59: Setting Up 35 resolution printer wi
Page 60 and 61: Setting Up 37 C A B C Traditional T
Page 62 and 63: Setting Up 39 Camera Light Source O
Page 64 and 65: Setting Up 41 Camera Light Source (
Page 66 and 67: Setting Up 43 FIGURE 2.37 (a) An ob
Page 68: Setting Up 45 FIGURE 2.41 (a) PCB p
Page 71 and 72: 48 Image Acquisition Processing wit
Page 93 and 94:
70 Image Acquisition Processing wit
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
100 Image Acquisition Processing wi
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 164 and 165:
6 Morphology When applied to vision
Page 166 and 167:
Morphology 143 I Closed { } = Erode
Page 168 and 169:
Morphology 145 FIGURE 6.3 Simple mo
Page 170 and 171:
Morphology 147 FIGURE 6.5 Custom st
Page 172 and 173:
Morphology 149 FIGURE 6.8 Particle
Page 174 and 175:
Morphology 151 FIGURE 6.12 Fill hol
Page 176 and 177:
Morphology 153 FIGURE 6.17 Danielss
Page 178 and 179:
Morphology 155 Detected circles wit
Page 180 and 181:
Morphology 157 6.5 CASE STUDY: FIND
Page 182 and 183:
Morphology 159 6.6 USER SOLUTION: D
Page 184 and 185:
Morphology 161 ULTRASOUND MACHINE (
Page 186:
Morphology 163 FIGURE 6.31 The Edit
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 240 and 241:
8 Machine Vision A generally accept
Page 242 and 243:
Machine Vision 219 TABLE 8.1 “IMA
Page 244 and 245:
Machine Vision 221 TABLE 8.3 Input
Page 246 and 247:
Machine Vision 223 packages, includ
Page 248 and 249:
Machine Vision 225 good sense to ad
Page 250 and 251:
Machine Vision 227 TABLE 8.4 “IMA
Page 252 and 253:
Glossary 1-Bit Image An image compr
Page 254 and 255:
Glossary 231 binary display device
Page 256 and 257:
Glossary 233 spatial Þlters, each
Page 258:
Glossary 235 Resolution There are t
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267:
show all

Image Acquisitionand Proces

Create successful ePaper yourself

Delete template?

Save as template?