Digital Sight ACT-1 for L-1 Software
Photo Panel Functions
The Photo panel is one of five settings panels, displayed within the main ACT-1 control window, directly beneath the small subwindow. Clicking the Photo tab displays the Photo panel at the forefront of the settings panels for access to its features, which include many of the exposure-related camera controls as well as certain hardware configuration settings (Figure 1). Cameras that are connected to a Digital Sight camera control unit on a network are capable of being controlled through the ACT-1 software. The camera to be connected for software control is selected by clicking on the Hardware Settings button in the Photo panel, which opens a dialog box that allows either entering the target camera's IP address directly or initiating a search feature to identify cameras connected to the local network (Figure 2). Once a connection setting is entered or selected from the list of networked cameras, the selection remains valid until changed, and will be the default camera connection each time the software is launched.
The upper region of the photo settings panel (Photo tab, illustrated in Figure 1) provides exposure-setting controls, including pull-down menus for choosing exposure mode (Mode) and photometry (metering) area (Area), and adjustment arrows for exposure compensation (CMP). A pair of radio buttons allows the selection of either an Average or Peak Hold method of exposure measurement. The lower portion of the photo settings panel includes Gain adjustment controls as well as the AE Lock button and the Hardware Settings button.
The Mode pull-down menu offers the same exposure mode choices that are provided through the native Digital Sight control system: Program, Focus, and Shutter speed automatic exposure (AE) modes, in addition to Manual mode. Further details of utilization of the various exposure modes, and the exposure compensation feature, are provided in the Digital Sight Exposure and Camera Sensitivity section. When manual setting of exposure variables is desired, Manual should be selected from the Mode pull-down menu. In manual mode, the exposure compensation control is disabled and the exposure time is specified by using the mouse pointer to drag the Exposure Time slider (illustrated in Figure 3). The selected exposure time is displayed numerically in the exposure time window, and can be changed in steps by clicking either of the arrows located at the ends of the slider. In addition to exposure mode and compensation selection, this area of the Photo panel provides a pull-down list for selection of the size of the image area to be utilized for exposure determination by the camera's metering circuitry. The choices provided are Large, Middle, and Small, with reference to the relative size of the photometry area.
Three mechanisms are provided within the ACT-1 software for modification of camera gain (sensitivity), and all may be accessed in the Gain area of the Photo settings panel (Figure 1). The Analog Gain setting adjusts the image brightness through direct control of the camera gain circuitry. The adjustment arrows allow the gain to be adjusted from the default value of 100 (x1) to 4600 (x46), and is enabled only when the Manual exposure mode is being utilized. The Digital Gain setting buttons may also be employed to adjust the image brightness level, although this method changes the brightness at the image output stage through pixel value calculations. Consequently, the procedure can be applied in any of the exposure modes as a correction to the camera gain setting. The digital gain is adjustable over a range of 20 to 260 percent, referenced to the default value of 100 percent.
The selection of a tone setting from the seven provided in the Tone pull-down list affords a third mechanism for image control through camera gain adjustment. The various tone settings apply modifications to the image gamma values that result in contrast and brightness changes in the output image. The characteristics of the different tone settings and the strategies for applying them to a variety of specimen types are described in the Digital Sight Image Correction Features section. The seven available tone (gamma) settings provided in the Tone pull-down list are designated by descriptive terms: Wide, Low, Middle, High, Linear, Metal, and Enhance. They are functionally equivalent to the settings referred to in the native Digital Sight control menu as TONE 1 through TONE 7.
The camera exposure set by the system in any of the automatic exposure modes can be locked by clicking the AE Lock button with the mouse pointer. The exposure lock is cancelled by clicking the button again. This feature is useful, for example, when specimen movement or another factor causes fluctuations in the image brightness, and it would be preferable to fix the camera exposure at an appropriate exposure level.
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