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STH-DCSG

 

U

SER

M

ANUAL

 

 

 

 

 

 

 

 

 

 

 

 

 

©

2005

 

V

IDERE 

D

ESIGN

 

 

18 

7 User 

Controls 

The CMOS imagers are fully controllable via the 1394 interface.  User 
programs may input color images (STH-DCSG-C only), set video 
digitization parameters (exposure, gain, red and blue balance), and 
subsampling modes.  All of these parameters can be set with the SRI Small 
Vision System.  They are also accessible to user programs through the 
capture API (Section 8). 

User controls for frame size and sampling modes are on the main capture 
window dialog.  Video digitization controls are accessed through a dialog 
invoked with the 

Video…

 menu item.  Figure 7-1 shows the dialog. 

7.1 Color 

Color information from the stereo digital head (STH-DCSG-C only) is 
input as raw colorized pixels, and converted by the interface library into 

two monochrome and one or two RGB color channels.  The primary color 
channel corresponds to the left image, which is the reference image for 
stereo.  The right image color channel is also available.  The color images 
can be de-warped, just like the monochrome images, to take into account 
lens distortion (see the Small Vision System User’s Manual). 

Color information from the camera is input only if the 

Color

 button is 

pressed on the main window (Figure 2-1). 

Because the typical color camera uses a colorizing filter on top of its pixels, 
the color information is sampled at a lower resolution than a similar non-
colorized camera samples monochrome information.  In general, a color 
camera has about ¼ the spatial resolution of a similar monochrome camera.  
The cameras have on-imager binning from 640x480 to 320x240 
(monochrome only).  Full-frame images at 320x240 use the binning mode.   

The relative amounts of the three colors, red/green/blue, affects the 
appearance of the color image.  Many color CCD imagers have attached 
processors that automatically balance the offsets among these colors, to 
produce an image that is overall neutral (called 

white balance

).  The STH-

DCSG-C provides manual color balance by allowing variable gain on the 
red and blue pixels, relative to the green pixels.  Manual balance is useful in 
many machine vision applications, because automatic white balance 
continuously changes the relative amount of color in the image. 

The manual gain on red and blue pixels is adjusted using the 

Red

 and 

Blue

 

controls on the 

Video Parameters

 dialog.  For a particular lighting source, 

try adjusting the gains until a white area in the scene looks white, without 
any color bias. 

7.2 Gamma 

Correction 

To display properly for human viewing, most video images are formatted to 
have a nonlinear relationship between the intensity of light at a pixel and 
the value of the video signal.  The nonlinear function compensates for loss 
of definition in low light areas.  Typically the function is x

γ

, where 

γ

 is 0.45, 

and the signal is called “gamma corrected.”   

 

Figure 7-1  Video Parameters dialog. 

Содержание STH-DCSG

Страница 1: ...STH DCSG USER S MANUAL 2005 VIDERE DESIGN 1 STH DCSG C Stereo Head User s Manual April 2005 2005 Videre Design...

Страница 2: ...IEEE 1394 Cable 13 5 2 IEEE 1394 Host Interface 13 5 3 Supplying Power 13 6 Lenses 15 6 1 Locking Lenses 15 6 2 C and CS Mount Lenses 15 6 3 Changing Lenses 15 6 4 Cleaning the Imagers 15 6 5 Imager...

Страница 3: ...e 11 Figure 5 1 External power supply connections 14 Figure 6 1 Range resolution in mm as a function of distance 16 Figure 7 1 Video Parameters dialog 18 Figure 7 2 Frame size and sampling controls 19...

Страница 4: ...to the STH DCSG C please see the STH DCSG VAR C manual for more information SRI s Small Vision System SVS software has an interface to the STH DCSG C and is included with each stereo head You can sim...

Страница 5: ...s high sensitivity the STH DCSG allows for very short exposure times even under moderate lighting conditions So it is appropriate for high motion applications such as outdoor robotics motion capture e...

Страница 6: ...be supplied see Section 5 3 The PC operating system will normally recognize the STH DCSG and install the correct system drivers Please see the Videre support web pages www videredesign com support ht...

Страница 7: ...e menu A more complete description of the video capture program is in Section 7 The SVS programs are described in the SVS User s Manual and the SVS Calibration Addendum documentation that comes with t...

Страница 8: ...de only that is each line is output in succession from the full frame The maximum video rate is 12 megapixels per second from each imager The imagers are synchronized to a common clock so that the cor...

Страница 9: ...oduce a smaller image with improved noise characteristics 3 3 50 Hz Operation Indoor lighting especially from fluorescent fixtures can oscillate at the frequency of the electrical supply If the image...

Страница 10: ...o is determined by the maximum bandwidth of the bus for isochronous transfers 32 MB s This rate cannot be exceeded by the combined video streams on the bus Table 2 shows the bandwidth requirements for...

Страница 11: ...Section 5 for information about cabling and power for the IEEE 1394 bus 4 1 2 Linux Hardware and Driver Installation Linux kernels 2 4 or 2 6 kernels are required for operation Please see the Videre D...

Страница 12: ...alibration libraries are not included the only way to run the SVS calibration procedures is through the smallvcal exe application smallv exe is a GUI based application that allows the user to exercise...

Страница 13: ...be added by installing a 1394 PCI card or PCMCIA card for laptops 1394 PCI cards have 6 pin ports and supply power PCMCIA cards do not have the capability of supplying power and come with an adapter f...

Страница 14: ...5 1 External power supply connections On the left is power supplied to a PC Card with a power port On the right power is supplied through a hub with a power port Power should be 7 to 16 VDC at 1 5 W...

Страница 15: ...older or lens threads Once the threads are engaged continue screwing it on until it seats firmly You can snug it down but do not tighten it excessively since this can damage the lens and the lens hold...

Страница 16: ...ution comes with it 6 8 Range Resolution Range resolution is the minimum distance the stereo system can distinguish Since stereo is a triangulation operation the range resolution gets worse with incre...

Страница 17: ...SER S MANUAL 2005 VIDERE DESIGN 17 Lens focal length Horizontal FOV Vertical FOV 2 8 mm 69 deg 54 deg 4 0 51 40 8 0 27 20 16 14 10 Table 3 Horizontal and vertical field of view for different lens foca...

Страница 18: ...rmation is sampled at a lower resolution than a similar non colorized camera samples monochrome information In general a color camera has about the spatial resolution of a similar monochrome camera Th...

Страница 19: ...r the STH DCSG C devices In manual mode the user program sets the exposure and gain The exposure and gain are based on a 0 to 100 scale Here are some tips for setting exposure and gain In general keep...

Страница 20: ...me size and sampling setting affect the output image Explicit control over the sampling mode is accomplished with the SetSample function from the SVS API The first two lines of the table are for full...

Страница 21: ...ice is downloaded and stored in the device and will cause 50 Hz operation every time the STH DCSG is accessed To change back to 60 Hz uncheck the box and again save it to the device It is also possibl...

Страница 22: ...STH DCSG USER S MANUAL 2005 VIDERE DESIGN 22 8 Interface Software API Please see the Small Vision System manual for information about the software API for capturing and saving images...

Страница 23: ...hysical Dimensions and Mounting Diagram The diagram below shows the physical dimensions for the STH DCSG C The larger hole is threaded for a 20 machine screw standard tripod mounting screw The two sma...

Страница 24: ...125 6 5 12 5 25 50 Hz Max 30 Hz at 640x480 Exposure 1 line time to full frame Gain 0 12 dB 1x 4x Sensitivity 4 8 V lux sec monochrome S N 60 dB no gain Power 1 W Synchronization Internal pixel locked...

Страница 25: ...STH DCSG USER S MANUAL 2005 VIDERE DESIGN 25 10 2 Imager Response Color 10 3 Imager Response Monochrome...

Страница 26: ...STH DCSG USER S MANUAL 2005 VIDERE DESIGN 26 10 4 Filter Transmittance...

Страница 27: ...hnical support please contact Videre Design by email or FAX Videre Design 865 College Avenue Menlo Park CA 94025 Fax 650 323 3646 Email support videredesign com Technical information about stereo algo...

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