Ch 3 – Preparing to Take a Picture
Image Setup Options
User’s Guide to the SPOT Cooled Color Digital Camera, 6/9/98
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Image Type (Auto-Exposure)
When using the Auto-Exposure option, the SPOT camera provides two Image Type
settings to choose from, Brightfield and Darkfield:
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Brightfield
– Use the Brightfield setting for transmitted light brightfield images.
The Brightfield setting instructs the camera to over-expose (burn out) the brightest
parts of the picture (i.e., the background). The additional exposure results in the loss
of detail to the background, the least important part of the image, and enhanced
brightness to the specimen, the most important part of the image.
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Note: Brightfield is the default setting for the SPOT camera.
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Darkfield
– Use the Darkfield setting for images where the specimen is the brightest
part of the image. The Darkfield setting instructs the camera to correctly expose the
brightest parts of the picture (i.e., the specimen). The Darkfield setting is ideal for
capturing fluorescent images.
The following two pictures illustrate a typical bright field image and a typical dark field
image:
Figure 1: Typical Bright Field Image
Figure 2: Typical Dark Field Image
Auto-Gain Limit (Auto-Exposure, 8 bit and 24 bit)
As described in Chapter 2, “Electronic Imaging Theory and the SPOT Camera,”
increasing gain enables the SPOT camera to capture dim images without using lengthy
exposure times. The Auto-Gain Limit feature allows you to set an upper limit on the gain
options that the camera has to choose from during the Auto-Exposure process.
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Note: The User-Defined Exposure option allows you to precisely set the gain for
an image capture.
