# Preferences

The Preferences... item in the Edit menu, brings up a dialog box in which one can set the default display behavior for new graphs. One can control the tick frequency, grid line colors, and scaling for graph axes; color, point styles, and line types for scatter plots; and colormaps and scaling of images. The window has a paned format in which the options affecting each part of the graph has a pane which can be brought forward by clicking the appropriately labeled tab.

- POW

           This pane sets the application level preferences for how POW
           looks and behaves.  Cursor sets the image to use as the
           mouse cursor when in POW's main window.  POW's "GUI" consists of
           the 3 pixel readouts, the Scopebox, and the Zoom In/Out buttons
           usually located at the top of the window.  The GUI
           Position option allows you to move these to any side of the
           window or turn them off altogether.  Scopebox Size alters
           the size of the scopebox -- the window showing a small overview
           of the current graph -- or hides it altogether.  Resize
           Window determines whether the POW window will get bigger or
           smaller (as far as possible) whenever you change the objects in
           the main POW window, so as to show you everything currently
           displayed in the main POW window without scrolling.
           Using the color grid or button, Background Color will set
           the color to use for the background of all of POW's windows.

- Graph

           This pane has been modified, containing a pair of entry
           boxes labeled Size, a set of buttons labeled
           Scaling and new control to choose functionality for
           right or left mouse buttons [More options are available when
           editting a real graph (see Edit Graphs).]  Enter
           into the Size boxes, the default width and height to use
           when creating a new graph.  When a graph is created by another
           program (such as fv), it determines the size of the graph, so
           these options are usually overridden.  The Scaling buttons
           activate logarithmic graphs.  The first row of linear and
           log buttons cause each axis to be drawn in either linear
           or logarithmic format.  This does not affect the data, just how
           the graph coordinates are interpretted and labeled.  You can
           control the logarithmic conversion of individual curve data from
           the Points and Lines panes.

           The mouse control button can be clicked to switch the functionality
           of mouse buttons. Default will be left mouse button to control image
           zoom factor, and right mouse button to control brightness/contrast.

- Fonts

           This pane controls the appearance of text in the graph.  One can
           independently set the font, size, style, and color of the Title,
           Axis Labels, Tick Labels, and default Text Labels.
           The Text Label value is used only for the initial text label.  All
           subsequent labels inherit their values from the previous label.

- Ticks

           This pane controls the appearance of the tick marks and
           associated grid lines.  Use the slidebars to indicate
           approximately how many tick marks should be drawn (and labeled)
           on each axis of the graph.  At the far left, no tickmarks will be
           drawn on each axis.  At the far right, about 30 may be drawn.
           The X Ticks and Y Ticks options control whether the
           X and Y tickmarks are drawn inside or outside the graph's box and
           whether they are labeled on the left and bottom axes.  The
           Tick Labels option selects between Decimal and Base 60
           (degrees minutes seconds) numerical formats.  Base 60 is only used
           when a graph contains WCS information.  If the Grid Lines
           checkbox is selected, lines will drawn on the graph, tracing the
           path of each tick mark coordinate.  One can control the
           Color and line Style (solid, dashed, etc) of these
           lines.

- Points

           The checkbox at the top of this item indicates whether the
           individual points of the curve should be drawn.  The points can
           be drawn as any of the 7 listed shapes.  The size
           of the points (except Dot which is always 1 point) can either be
           fixed at a constant size indicated by the slidebar, or
           drawn with widths/heights indicating the X and Y error
           bars.  If there are X/Y error bars but the points are drawn
           in a fixed style, the error bars will be indicated by
           horizontal/vertical lines centered on the point.  Points can be
           Filled or just drawn in outline.  Finally, select the
           desired color from the displayed colorbar.  This can be a
           different color than selected in the Lines pane.

           At the bottom are a pair of LogX/logY checkbuttons labeled
           Transform (This is the same option as in the Lines pane).
           Checking these will cause curves to have the logarithm of their
           data plotted instead of the data itself.  This does not
           automatically result in logarithmic axes, which are turned on
           from the Graph pane.  Unless you will always want your data to be
           converted to a certain logarithm format, these options should be
           left unset.

- Lines

           The checkbox at the top of this pane indicates whether data
           points will be connected with a continuous line.  The line can be
           of several patterned styles or widths.  The points
           can also be connected directly (Normal) or in a
           stair-step pattern (Histogram).  In the latter mode, the
           Fill Boxes option draws the histogram as a series of solid
           boxes instead of an outline.  Finally, select the desired color
           from the displayed colorbar.  This can be a different color than
           selected in the Points pane.

           At the bottom are a pair of LogX/logY checkbuttons labeled
           Transform (This is the same option as in the Points pane).
           Checking these will cause curves to have the logarithm of their
           data plotted instead of the data itself.  This does not
           automatically result in logarithmic axes, which are turned on
           from the Graph pane.  Unless you will always want your data to be
           converted to a certain logarithm format, these options should be
           left unset.

- Image

           This pane controls the appearance of images.  Most of the pane
           consists of a bunch of different colormaps.  They are grouped in
           the same sequence as listed in the Color menu: smooth, continuous
           colormaps, followed by ramps, then the step functions.  The
           Invert option will reverse the order of the colormap when
           turned on.  The Scaling option controls how the colormap
           is applied to the image.  For Linear scaling, each
           colormap level corresponds to a constant intensity range in the
           image.  Square-Root scaling changes the mapping such that
           the intensity range covered by each color level increases as the
           square-root function, producing higher contrast at lower
           intesities.  Logarithmic scaling uses the logarithmic
           function for colormapping, giving even more contrast at low
           intensities than sqrt.  Histo Equalize scaling computes
           a histogram of the image and tries to distribute colors equally
           over the number of pixels.

Clicking the Reset button will revert the options to their values when the dialog box was initially opened, undoing any modifications. Clicking the Save button will make the current settings the defaults for new graphs and save them in your .powrc file. The Get Current button grabs any available options from the current graph. Its current image (if present) will be used for the default image options and its first curve (if present) for the default curve options. Exitting will also make the new settings the current defaults, but won't save them.