1. SILICON VIDEO® 1281, 1281C 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® 1281 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 Black Level allows adjusting the camera's black level. The Gain allows adjusting the camera's gain. Increased gain allows capturing dark scenes, but at the expense of slightly decreased image quality (increased random noise); Whenever possible, increase illumination or increase exposure instead of increasing gain.

The Exposure allows adjusting the camera's exposure (shutter) period when the camera is in Video mode (below). 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 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. 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 Pixel Clock allows specifying the pixel clock rate. A faster pixel clock increases the 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 Mode allows selecting Video or Controlled frame mode. In Video 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® D2X frame grabber.

 

1.4. Color Cameras

For color cameras with so-called ''Bayer format output'', it is XCAP software which 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. From the PIXCI® Image Viewer, click:
    Capture
    Adjustments
    AGC
Select whether gain, or exposure, or both, should be modified to darken a too-bright image or brighten a too-dark image:
    AGC Adjusts Gain
    AGC Adjusts Exposure
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.

Finally click:
    AGC On
to enable AGC.