Navigating Images



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Navigation Modes

Readout Mode

Zoom In / Zoom Out Modes

Pan Mode

Center Mode

To Select a Navigation Mode

Image View Tool Bar

Keyboard Shortcuts

Temporary Keyboard Switching Combinations

Image Window Context Menu

Image > Mode Main Menu Item

Zoom Commands

Zoom In (Increment Zoom Ratio)

Zoom Out (Decrement Zoom Ratio)

Predefined Zoom Ratios

Zoom To Fit

Fit Window

To Execute zoom Commands

Zoom Tool Bar

Keyboard Shortcuts

Image Window Context Menu

Window Main Menu Item


Direct inspection and measurement of pixel data comprises some basic but important functions of every image processing application. In this section we'll describe everything you need to surf your images thoroughly with PixInsight.


Navigation Modes

There are five navigation modes available for open image windows in PixInsight:


Readout Mode

This is the normal operation mode, and also the default mode when you start PixInsight. In this mode, you can read coordinates and pixel values directly from the current view of the active image window.

The readout mode also lets you obtain direct pixel readings in the Histograms and Curves processing windows, which plays an important role in the usage of these fundamental tools.

The way pixel values are read and represented can be controlled and customized through a specific global settings object known as Readout Options. We'll further elaborate on these topics in dedicated sections.


Zoom In / Zoom Out Modes

In these modes you can magnify or reduce, respectively, the representation of the current view's pixels on the screen. PixInsight supports integer zoom ratios only. For magnification, possible ratios are 1:1, 2:1, ... up to 32:1; for reduction, 1:2, 1:3, ... down to 1:16.

In a zoom mode, you can zoom by simply clicking at any location on the image, or by clicking and dragging to define a rectangular zooming area.

An alternate way to zoom in/out is to use the mouse wheel. This works independently of the currently selected navigation mode.


Pan Mode

Pan actually stands for panoramic. When the entire view doesn't fit in the image window's client area, this mode lets you scroll the image by clicking on any point of it and dragging the mouse cursor.

You can constrain the panning action horizontally or vertically by pressing the Shift key while clicking the mouse; then the first movement you perform will define the constrained panning direction. Panning in a constrained direction is much faster than doing it freely in both directions.

In addition to the pan mode, you can use standard scroll bars on the right and bottom edges of any image window when applicable.


Center Mode

This mode allows setting the center of view at a specific pixel location. It is similar to the pan mode, but with the center mode you make a single click where you want to go, instead of clicking and dragging.

A rectangular area can also be defined in center mode; in this case, the center of view will be the center of the rectangular area once the mouse button is released, but no zooming action will be performed.


To select a navigation mode:

  • Image View Tool Bar
    The best way to select one of the five available navigation modes is to make use of their associated tool buttons. You'll find them on the Image View tool bar, which is visible by default:

If the Image View tool bar is not visible, you can show it with the Window > Tool Bars > Image View option of the main menu.

  • Keyboard Shortcuts:

    To select this navigation mode:

    Press these keys:


    Readout

    Alt-R

    Zoom In

    Alt-Z

    Zoom Out

    Shift-Alt-Z

    Center

    Alt-C

    Pan

    Alt-P

    Note that when an image window is the current active window in the main window's client area (you know this by its highlighted title bar), you don't have to press the Alt key to select navigation modes; for example, pressing the Z key is sufficient to select the zoom in mode.

  • Temporary Keyboard Switching Combinations
    There are three keyboard combinations that will allow you to activate a given navigation mode temporarily, so that when you release the combined keys the previously active mode is restored. This is a very useful feature —once you learn temporary switching combinations, you won't want to live without them:

    To temporarily switch to this mode:

    Press these keys:


    Zoom In

    Ctrl-Spacebar

    Zoom Out

    Ctrl-Alt-Spacebar

    Pan

    Spacebar


  • Image Window Context Menu
    You access this menu by right-clicking on any view of an image window.



  • Image > Mode Main Menu Item


Zoom Commands

There is a series of keyboard shortcuts, menu options and tool buttons that allow you to quickly select a desired zoom ratio for the current view of the active image window. Zoom ratio is a local working parameter, that is, each view keeps its own zoom ratio and applies it for drawing itself on its 'mother' image window when it is selected as its current view.


Zoom In (Increment Zoom Ratio)

This command increments the zoom ratio of the current view. Maximum zoom ratio is 32:1.


Zoom Out (Decrement Zoom Ratio)

Use this command to decrement the zoom ratio for the current view. Minimum zoom ratio is 1:16.


Predefined Zoom Ratios

This comprises a set of commands that correspond to frequently used zoom ratios. This set includes: 1:1 (actual size); for magnification: 2:1, 3:1, 4:1, 6:1, 8:1; for reduction: 1:2, 1:3, 1:4, 1:6, 1:8.


Zoom To Fit

This command automatically selects the maximum zoom ratio usable to view the whole image. The selected zoom ratio depends on the size of the view and on the available space on the main window's client area, hence it is dependent on screen resolution and image dimensions.

If you use this command and the image window is maximized or minimized, it is restored before applying it.


Fit Window

This command tries to adjust an image window's width and height to fit exactly the contents of its current view at the current zoom ratio. This is only possible if the view can be seen entirely in less than or equal space to that available in the client area of the window.

Again, if the window is maximized or minimized, this command restores it.


To Execute Zoom Commands:

  • Zoom Tool Bar
    This tool bar includes tool buttons to quickly access many of the zoom commands listed above.

The Zoom tool bar is visible by default; if it isn't, use the Window > Tool Bars > Zoom main menu option.

  • Keyboard Shortcuts:

    To execute this zoom command:

    Press these keys:


    Zoom In (Increment Zoom Ratio)

    Ctrl-Up

    Zoom Out (Decrement Zoom Ratio)

    Ctrl-Down

    Zoom Out

    Shift-Alt-Z

    Zoom 1:1 (Actual Size)

    Ctrl-1

    Zoom 2:1

    Ctrl-2

    Zoom 3:1

    Ctrl-3

    Zoom 4:1

    Ctrl-4

    Zoom 6:1

    Ctrl-6

    Zoom 8:1

    Ctrl-8

    Zoom 1:2

    Shift-Ctrl-2

    Zoom 1:3

    Shift-Ctrl-3

    Zoom 1:4

    Shift-Ctrl-4

    Zoom 1:6

    Shift-Ctrl-6

    Zoom 1:8

    Shift-Ctrl-8

    Zoom To Fit

    Ctrl-0

    Fit Window

    Ctrl-W


  • Image Window Context Menu:

You access this menu by right-clicking on any view of an image window.

  • Window Main Menu Item:



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