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Calculate Image Scale
The Calculate Image Scale command is a
utility command that calculates the number of arcseconds per pixel
for angular projections onto the image.
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The Calculate Image Scale command opens
from the Image Window > Process
> Utilities menu and  button on the Main Toolbar. The "immediate" form, shown first,
opens when an image or image set is displayed in the top-most
window. The general form can be used to select source images from
folders, windows, or by matching templates.
Calculate Image Scale Properties
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Profile [|>]
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Selects the parameter profile for this command and
allows you to save or work with existing presets.
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[Select]
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Opens the
Select Source Images dialog to choose images from an
image window, folder, files, name template, or a Mira File
List.
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Load from Image
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The two values in this column may be taken from
keywords in the image header. To do so, specify the keyword and
click the  button to transfer the
keyword's value to the (mm)
field..
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Focal Length
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Enter the focal length in units of mm or select a
previous value from the list. Use the [+] and [x] buttons to add or
delete the currently displayed entry.
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Pixel Size
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Enter the pixel size in units of microns or select
a previous value from the list.. Use the [+] and [x] buttons to add
or delete the currently displayed entry.
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(mm)
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Alternately, type in the focal length instead of
taking it from an image header keyword.
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(microns)
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Alternatively, type in the pixel size instead of
taking it from an image header keyword.
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Click this button to calculate the image scale
from the specified quantities.
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The image scale in units of arcseconds per pixel is
labeled arcsec/pixel in the dialog.
To compute this value, Mira uses the focal length in units of
millimeters (mm) and the image pixel size length in units of
microns. These values can be obtained from two sources: From you or
from the image itself using header keywords for the Focal Length andPixel
Size. After the values are entered into the two fields,
click  (calculate) to compute the image
scale.
Obtaining Input Values from the Image
The Focal Length and
Pixel Size are often stored in the
image using header keywords. To load these values from the image,
use the two History boxes on the left side of the dialog. These
boxes remember previously entered values which can be recalled, or
you can type new keyword names into the fields. When the keyword(s)
are visible in the combo box field(s), click to load the value(s) from the image header. To
compute the image scale, click the button.
Related Topics
Set Arcsecond Scale
Calculate Airmass
Mira Pro x64 User's Guide, Copyright Ⓒ 2023 Mirametrics, Inc. All
Rights Reserved.
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