Comet Labs WN591 Manual de usuario descargar pdf (Pagina 15)

Help! There is a comet in my computer! 12

Figure 6. Geometric calibration of the image analysis system. We record an image of a micrometer

ruler under a microscope with a camera and then measure the distance between the micrometer

markings on the recorded image. In this case, the scaling factor is 200µm / 375 pixels = 0.53 µm

per pixel.

Note that the objective magnification is not the only parameter that affects the scaling of

images. In some microscopes, additional magnification lenses can be either inserted or

removed from the optical path. Another important parameter is binning, a camera setting

that we will discuss later (see chapter Binning, page 40). A separate geometric calibration

is needed for all combinations of settings of the image analysis system (on the

microscope, the camera or in the software) that affect image scaling.

3.4 Measurement of geometric parameters

Let us assume that the scaling factor for our model image is 1.6 µm per pixel. We can

calculate that the tail length of 14 pixels corresponds to 22.4 µm, so the tail is now

measured in absolute units. Other geometric parameters of the comet, such as the length

of the comet, the length of the head, the area of the comet, the area of the head and the area

of the tail can be measured using the same procedure of counting the pixels with a

consideration for the scaling factor of the image. These parameters describe lengths and

areas and are called geometric parameters.

200

m = 375 pixels

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Comet Labs WN591 Manual de usuario Pagina 15