- 2 Inputs, 1 Output
-     See only the difference between pictures
-     See only motion by continually showing the difference between successive frames.
- Freeze either input
-     Store an image for reference or continual comparison
|See the new Video Comparator Series 618 if, in addition to Video Subtraction, you also need:
- Split Screen
-     Left-Right or Top-Bottom
-     Adjustable Split Position
-     Double Exposure Effect
-     Adjust the proportion of each input
-     Fade, disolve, or overlap from one picture to another
The Model 442 Series High Definition Video Subtractors show the differences between two images on one monitor.
Subtract or Compare mode allows you to subtract or compare two video images. The unit performs a video image comparison by subtracting the image stored in its memory from the active picture at its input or subtracting one live picture from another live picture. Comparison (subtraction) of two live video streams is also possible. This mode is very useful for inspection, registration, interferometry, quality control, surveillance
and other applications where an easily viewed comparison of two video images can be used for decision making or process control.
The Subtract or Compare mode has two selectable output modes. One provides the difference
plus 0.5. The other provides the absolute value of the difference. Additionally, a button is provided to invert
the output thereby showing the reference minus the input instead of the input minus the reference. A "Difference
Threshold" control allows adjustment of the unit's sensitivity to differences.
An additional operational mode allows subtraction of each video frame from the previous frame to provide
"frog's eye" capability, displaying only motion in the scene being monitored by the input video camera.
MP4 Video showing an example of using Video Subtraction for an Alignment Application (right click to download and then view using Windows Media Player). The first six seconds show an image of a PC board that is stored in the Video Subtractor's memory as a reference. At six seconds the screen goes dark because we've switched to a mode where the live video from the camera is compared to the stored reference image. The dark screen indicates that there is no difference between the live video and the reference image. At 11 seconds, we shift the board's position 3/1000 of an inch to the left. Given the entire field of view is 4.5 inches across, the 0.003 inch shift represents a 0.06% change. The resulting image shows the alignment error between the live image and the reference image.
When connecting the DD442CS Hi-Def Video Comparator to an HDMI-licensed device, we recommend using a 6 foot Male DVI to Male HDMI Cable or Adapter. Inputs A and B must be of identical resolution.