Virtual Camera Description

A camera has a maximum viewable area that is measure in number of pixels wide times number of pixels high. A standard video rate camera might be 640x480 and a typical digital camera might 1024x1024.

Sometimes we want to view the full image at a lower resolution. This is done by binning. We divide an image into bins which are composed of a square area of pixels. An image is created by averaging the pixels in each bin and creating an image based on these binned values. A bin factor of 2 on a 1024x1024 image would result in a 512x512 image of the same area (the even and odd rows and columns are averaged together). Some cameras will have this function built in, in other case the library implementation would be responsible for binning the image as requested. (A WICS Server running a camera would implement the binning function if the camera did not support it).

Effective image area is the actual image area divided by the binning factor. Thus if you set a bin factor of 2 on a 1024x1024 camera the effective image area becomes 512x512 and all measurements are relative to this figure.

Partial acquisition of images allows just a rectangular area of the full effective image view be acquired. Perhaps we just want to view the upper left 256x256 of a 1024x1024 image. Thus we can specify the two corners measured relative to the effective image area for image acquisition.

Exposure settings specify how long the camera exposes the imaging area of the camera to the electron beam (some cameras this cannot be changed, should we return an error if a change is attempted or silently ignore the value, or silently accept the value [a later get will return the set value]).

Acquisition mode specifies how the camera should preprocess the image. Possible modes include unprocessed, gain normalized, darkfield subtracted. Sometime the camera will handle these functions other times the camera's WICS server would handle it, and there is always the option to let the client handle (hence the unprocessed option).

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