The DXM 1200 is equipped with a software feature that is utilized to specify the conditions for determining white balance for digital images. Either a single point or a rectangular marquee-selected area on the image can be specified for measuring the white balance.

	Interactive Java Tutorial
ATTENTION Our servers have detected that your web browser does not have the Java Virtual Machine installed or it is not functioning properly. Please install this software in order to view our interactive Java tutorials. Visitors using the Netscape and Microsoft Internet Explorer browsers can download the appropriate software from the websites where the browsers are distributed. Please do not contact us for information about specific URLs where this software can be obtained.

This interactive tutorial is designed to operate in a manner identical to that of the Nikon DXM 1200 ACT-1 software. To activate the white balance adjustment within the DXM 1200 software, click on the Live tab in the ACT-1 window to display the features available in this settings panel (see the applet figure). Before attempting to set the white balance, carefully examine the image to determine the appropriate area that should be selected for the adjustment. In stained thin sections, an area devoid of stained tissue should be utilized. Some biological stains can bleed through the mounting medium and contaminate the areas between tissue sections, so avoid these parts of the specimen. Images viewed in polarized light, differential interference contrast, fluorescence, or other contrast enhancing techniques can present more difficulty in white balance determination.

When the appropriate white balance area has been chosen, select either the Point (eyedropper icon) or marquee selection (Rectangle Area) radio buttons in the White Balance section of the Live settings panel to activate the measurement mode. If the area to be measured is very small (limited to only a few pixels), then the Point (eyedropper) tool should be chosen for more accuracy in the exact location of the selection. To activate the Point sampling tool, click on the eyedropper button in the settings panel. This will initialize the Start software routine, which deactivates the exposure frame and focus mark overlays and allows selection of a point in the image. When a specific point in the image is chosen, the measurement position can be specified when the tip of the eyedropper icon is located directly on top of the point and the mouse button is clicked once.

A more accurate method of selecting an area for white balance adjustment is to utilize the marquee selection (Rectangle Area) tool. After clicking on the appropriate radio button, move the cursor to the desired position within the live image window and drag the mouse to specify a rectangular selection. When the Start button is depressed, the software will proceed with a white balance calculation and the Measuring White Balance dialog box appears. At this point, the calculation can be halted by clicking on the Stop button in the dialog box.

The specimen area should always be carefully selected for white balance measurement, because artifacts in the specimen can often lead to errors in the determination of white balance. Differences in refractive index for the specimen or the presence or absence of a cover glass can lead to spherical aberration, which can affect the measurement (although in a minimal manner). As mentioned above, bleeding of biological stains can also induce color shifts in the mounting medium, leading to errors in white balance calibration. Wherever possible, use the marquee-selection tool to choose the largest area available for white balance determination. This allows the software to average white balance calculations over a greater number of pixels and will generate more acceptable results. In some cases, especially when only a single pixel is selected, the overall white balance determination can be compromised leading to images that are not adjusted properly.