PixInsight 1.5

The Officially Unofficial Reference Guide

Rev.0.1 – 3/29/2010

Section 8: Image


The CreateAlphaChannels process will add a new alpha channel with the luminance of the target image, or with a constant transparency value. Optionally one can use this process to replace an existing alpha channel.

From Image: When enabled, the alpha channel is created from the luminance of the image specified in the view selection list.

Invert: The alpha channel will be created from the inverted luminance of the source image.

Close source: Once the alpha channel is created, close the image used as the source image.

From Transparency: When enabled, the alpha channel is defined as a constant transparency value, specified in the box/slider below this check box.

Replace existing alpha channels: When checked, the newly created alpha channel will replace an existing alpha channel.


The ExtractAlphaChannels process can be used to obtain a copy of one or more of the alpha channels in an image, as independent grayscale images. Then you can modify them any way you like, then add them back with the CreateAlphaChannels process. This process can also be used to delete one or more alpha channels from an image.


Here you select whether you want to extract all of the alpha channels in an image, only the active alpha channel or the alpha channels you decide. This last option requires you to enter the alpha channel Ids.


Extract alpha channels: The default operation, which will extract the selected alpha channel(s).

Delete alpha channels: Rather than extracting them, by selecting this option, the selected alpha channels will be deleted.


This process will display the header information contained in the target FITS image. It only works – obviously – with images using the FITS format.

Besides viewing the existing values, you can add, replace and remove entries. To add new entries, enter the information in the Name, Value and Comment parameters.

HIERARCH Convention: When enabled, the parameters will conform to the HIERARCH convention, which indicates that keywords longer than 8 characters and that contain the full range of printable ASCII values are allowed. When disabled, the FITS Standard convention is used.


Use the ImageIdentifier option whenever you wish to give any given image or view a different identifier (name).


Use NewImage to create a new image from scratch.

Image Parameters

Identifier: Enter here the identifier for the new image. If left with the default <Auto> option, PixInsight will use the following naming convention: ImageXX – where XX is an incremental number: the identifier of the first image created will be Image01,the second one, Image02,etc..

Sample format: Indicate the format (bit depth) for the new image.

Color Space: Select whether the new image will be a color (RGB) or a grayscale image.

Width/Height: The width and height of the new image, in pixels. The size number that appears between the Height and the Set As Active Image is the calculated size in megabytes of the image to be created, based on the information entered here.

Channels: The number of channels in the new image.

Set As Active Image: When clicked, the parameters in the NewImage window will be populated with the corresponding data from the active image.

Initial Values

R, G, B, A: The new image can be completely black (RGB values of zero) or created with an evenly distributed color.


SampleFormatConversion is used to change (convert) the format of an image to the format specified. Generally speaking, the 32-bit floating point format is the preferred for processing most astroimages.


Invoke this process to obtain statistical data from any given view or image. The list of the statistical data shown, which should be self-explanatory, is as follows:

In the view selection list you specify the image/view from where you want to seethe statistics.

Scientific notation: Display the statistical data in scientific (exponential) notation, rather than the standard decimal notation.

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