1. SILICON VIDEO® WGA-M, WGA-C Video Adjustments

 

1.1. Video Resolution

Reducing the video resolution (the number of pixels captured per line and column) allows capturing more video frames in a given size of frame buffer memory. From the PIXCI® Image Viewer, click:

    Capture
    Adjustments
    Res(olution)
Click:
    Set Video Window
and draw the new desired area to be captured by left clicking and dragging over the displayed image. Click:
    OK
to accept the new capture resolution. Note: Changing the capture resolution will destroy any images previously captured in the frame buffers!

The

    Capt(ure)
    Frame Buffers
shows the number of frame buffers available with the current selections.

 

1.2. Saving the Video Configuration

The selections under the PIXCI® Image Viewer:

    Adjustments
are automatically saved when the PIXCI® frame grabber is closed, and/or XCAP is exited. When the PIXCI® frame grabber is next opened, clicking (from the XCAP Main Window):
    PIXCI®
    PIXCI® Open/Close
    Camera & Format
Choose:
    Open w. last used Video Setup
to use the previous video setup, or choose:
    Open w. default Video Setup
to start afresh with the default video format and resolution.

 

1.3. Camera Controls

XCAP integrates controls for both the PIXCI® frame grabber and the SILICON VIDEO® WGA camera within the Capture & Adjust window. The left side of the Capture & Adjust window contains controls for the PIXCI® frame grabber. The right side of the Capture & Adjust window provides camera specific controls.

The Gain allows adjusting the camera's gain. Increased gain allows capturing dark scenes, but at the expense of decreased image quality (increased random noise); Whenever possible, increase illumination or increase exposure instead of increasing gain. The Digital Gain allows adjusting the camera's post A-D digital gain; values lower than 0 dB are typically useful only for special applications.

The Exposure allows adjusting the camera's exposure (shutter) period. When using AC powered lighting, an Exposure which is a multiple of half of the power line's period (i.e. 16.6/2 msec. in the U.S. and other locations using 60 Hz, 20.0/2 msec. in Europe and other locations using 50 Hz) is suggested to prevent varying image brightness due to the illumination's cyclical change of brightness. Selecting Exp. Mult. of 1/50 or Exp. Mult. of 1/60 automatically forces the Exposure to a multiple of the corresponding period.

The Scan Direction allows adjusting the direction in which pixels are read-out, allowing inversion or mirroring of the image.

The AOI Left, AOI Width, AOI Top, and AOI Height allow selecting an area of interest which is read-out and captured. Capturing fewer columns or fewer lines decreases the image size and allows a faster frame rate (reductions below 618 columns only reduces the image size but does not further increase the frame rate). If Center Aoi L(eft)-R(ight) or Center Aoi T(op)-B(ottom) is selected, the AOI Left or AOI Top, respectively, is automatically adjusted so as to center the capture AOI, the AOI Width or AOI Height, within the camera's field of view.

The Subsampling allows selecting subsampling (decimation) of the AOI by a factor of ×2 or ×4 vertically, producing an image of lower resolution with smaller size, and allowing a faster frame rate.

The ADC Mode allows selecting a Companded pixel mapping instead of a Linear mapping. The Companded mode produces pleasing images with fewer adjustments of Gain and Exposure, while the Linear mode is often required for machine vision applications.

The Pixel Clock allows specifying the pixel clock rate. A faster pixel clock increases the allowable frame rate, but with reduced image quality (increased fixed pattern noise); a slower pixel clock increases the allowable exposure periods for longer integration and greater sensitivity.

The Video Mode allows selecting Free-Run or Controlled frame mode. In Free-Run mode the camera exposure and read-out is free-running; continuously exposing and sending frames to the frame grabber at a constant frame rate without need of a trigger. In Controlled mode the Controlled Frame Rate, Continuous, and Single Shot provide frame rate and triggering control through the PIXCI® SI, SI1, SI2, or SI4 frame grabber.

The Strobe Mode and Strobe Duration allows enabling an output strobe to synchronize a flash or other external device to the camera's exposure.

 

1.4. Color Cameras

The color cameras offer two different color modes. With ADC Mode set to Companded, the Companded Color can be set to Neutral or Warmer scene color. This provides pleasing, though not precise, color for many applications.

Alternately, with ADC Mode set to Linear, the XCAP software performs color adjustments and white balancing, not the camera.

From the PIXCI® Image Viewer, click:
    Capture
    Adjustments
    Color (or Clr)
For most common conditions:

  1. Select one of the pre-defined correlated color temperatures, either based on best appearance, or matching the color temperature of the current illumination. The 5000°K selection is average overcast daylight, the 4100°K selection is a typical cool white fluorescent bulb, and the 2800°K selection is a typical 60 to 100 watt tungsten bulb.

  2. Choose one of the predefined color qualities, trading quality for speed.

  3. If none of the predefined settings is satisfactory, start with the best setting and click:
        Customize
    
    Cover the camera's lens and click:
        Black Balance
    
    Finally point the camera at a white target (but preferably not a target using fluorescent brighteners) and click:
        White Balance
    

 

1.5. Automatic Gain & Exposure Control

The AGC controls provide automatic adjustment of the camera's gain or exposure as the image intensity changes. The Auto Exp. Control enables automatic exposure control (AEC), the Auto Gain Control enables automatic gain control (AGC).

Using only gain adjustments avoids increased blur due to moving objects when exposure is increased. Using only exposure adjustments avoids increased pixel noise at high gain settings. The AEC Maximum, AGC Maximum, AGC Update Period, and other parameters limits the maximum exposure set by AEC (and thus blur of moving objects), limits the maximum gain set by AGC (and thus the pixel noise), and allow otherwise ''tuning'' the response of AEC and AGC.