User manual

Small Vision System User Manual 23
2.3 Display
smallv displays two images in its display area. The left display is always the left input image.
Input images are displayed in grayscale, unless color information is present: in this case, the left image will
be shown in color.
The right display can be either the right input image, or the results of stereo processing. Processing
results are always displayed in “greenscale”, using shades of green.
Either display can be turned off by unchecking the box underneath the display area. Turning off the
display will let smallv run faster.
Images larger than 320x240 are automatically scaled down by factors of 2
n
to fit into a 320x240 area.
Smaller image sizes are displayed in the original size.
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.” Digital cameras, such as the MEGA-D, do not necessarily
have gamma correction. This is not a problem for stereo processing, but does cause the display to look
very dark in low-light areas. You can add gamma correction to the displayed image by choosing an
appropriate gamma value in the slider under the right display window (Figure 2-1).