# Edit Graph

A POW Graph consists of a number of Curves and Images drawn within a given rectangular region. The Edit Graph item in the Edit menu brings about a dialog box from which one can control what objects are drawn, how they are displayed, and how the graph itself is drawn...

The dialog box consists of 3 major regions. The top portion controls the contents of the current (or new) graph. The box on the left lists the objects currently in the graph. The box on the right lists all the available objects which are not in the graph. In both boxes, the type of each object (image or curve) will be indicated in parentheses after the objects' names. The Add and Remove buttons in between allows one to move the selected objects between the two lists. The name of the graph being editted is given below the left box. This can be changed if one wants to create a new graph rather than modify the current one. The Edit Objects button under the right box opens up another dialog box which allows one to edit the data structures which define Curves and Images.

The second region, below the graph contents section, contains the editable display options for the graph and graph objects. It has a paned format. At its top are a series of labeled tabs. Click on one of the tabs to view and edit that set of options. Each tab and its options are described below...

- Graph

  This pane contains the highest-level options affecting a graph's appearance. The first entry box contains the graph's title string. By default it is the graph name used internally by POW, but it can be any string or even blank. The entry boxes list, for both the X and Y axes, the Label to be written, the Min and Max values of the axis (actually, the lower-left and upper-right bounds of the graph's display region), the Units label of the values (printed within parentheses after the axis label), and the Size of the graph on the screen in pixels. Any or all of these may be NULL which tells POW to use the default values. In the case of the bounding box (Min/Max), default values will be determined by the minimum values required to display all the graph's contents. For Units, a NULL value will indicate not to list any units in the label axes. Clicking the Reset Min/Max button at the bottome sets all the bounding box values to NULL.

  Below the entry boxes are a set of buttons labeled Scaling. These 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. The Scale curve data to axes check button determines whether the curves in this graph will be converted to the same axis format. Do not check this if any of your curves already contain logarithmic values (instead of the true values) and you only need to change how the axes are displayed, not how the curves are plotted. You can control the logarithmic conversion of individual curve data from the Points and Lines panes.

- 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 of the pane is a pair of LogX/logY checkbuttons. Checking these will cause this curve to have the logarithm of its data plotted instead of its true values. If the data is logarithmic already, leave these options unchecked, but select the appropriate Scaling mode in the Graph options (see above).

- 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 of the pane is a pair of LogX/logY checkbuttons. Checking these will cause this curve to have the logarithm of its data plotted instead of its true values. If the data is logarithmic already, leave these options unchecked, but select the appropriate Scaling mode in the Graph options (see above).

- 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. The Range entry boxes at the bottom list the intensity range over which the colormap should be applied. Initially, they will contain the full intensity range of the image. The Reset button resets these values to the full range of the image.

At the very bottom of the dialog box are 3 buttons. Apply will update the selected graph using the modified parameter values. The Reset button will reset the parameter options and object lists based on the currently selected graph (for when one either wants to revert to the original parameters, or if one selected a new graph, or if new objects were created). The Exit button closes the dialog box. Any changes will be lost if not Applyed before exitting.