SAOimage display of M-51

SAOimage Usage

SAO/TDC Home Page
Refer to the SAOimage User Manual for detailed descriptions of all functions.

Most control actions take place within the context of a mode. Modes are selected by clicking on menu buttons in the top row of the button panel. Each menu mode brings up its own submenu buttons (the lower row in the button panel) for mode specific selections. Actions and submodes are selected by clicking on buttons in the submenu row of the menu panel.

The mouse controls specific functions in both the main display window and the pan/zoom window. In the main display window, the function of the mouse is determined by the mode and submode selections from the button menu. The function can also be recognized by the appearance of the mouse pointer icon.

The button interface is designed to be user friendly. The user is encouraged to try any and all buttons to become familiar with their functions. To exit, use the QUIT button in the etc submenu (click on \etc, then click on \QUIT).

Reading images

To read an image directly from a file, give its name anywhere on the command line. The -name switch is needed only when the image file name could be mistaken for a number or switch. SAOimage recognizes the \.fits and \.imh filename suffixes as belonging to FITS and IRAF OIF files. All other file types must be specified by an appropriate file type switch.

Raw array file types must be specified by an array data type switch (-u1, -u2, -i2, -i4, -r4, -r8) followed by width and height dimensions. To skip over a file header, use the -sk switch followed by the number of bytes. This can also be used to skip over entire images, if more than one are stored in the same file.

Use with IRAF

To emulate imtool and communicate with IRAF tasks, use either the -imtool or -pros switch. The two switches indicate which file format to use in recording saved cursors or regions. With -imtool, an IRAF list file containing only center coordinates is used (like that of imtool). With -pros, a file containing a full description of the saved cursors and their dimensions is used. The latter file can be read by tasks in the IRAF PROS spatial package for making image masks and performing image analyses. Both file types are ASCII and can be read and edited by the user. In either case, the file is not actually written until the user clicks on the write button in the \region submenu. Both file types can be read back to reproduce the saved cursors.

New command input

A new command line can be entered at any time, by selecting the new button in the \etc submenu or striking the N key on the keyboard. This allows the user to read in new images, change in and out of -imtool or \pros mode, set new scaling parameters, or change the number of reserved display color cells. Most command line switches (except -d, -g, -gd, -red, -green, -blue, and -vertgraph) will be accepted at any time.

When a new command line is requested, the previous command line is presented in an emacs-like popup editor for editing. Ctrl-N clears the previous line. Striking the RETURN key enters the line in the popup window as the new command. Ctrl-C returns with no action taken.

Using the Mouse

Most mouse interactions are based on mouse dragging (holding a button down while moving the mouse). The user should try clicking and/or dragging the mouse in each subwindow to become familiar with its functions. Modes selected in the button panel determine the response to the mouse buttons in the main display window.

In Scale mode, the mouse buttons control blinking of displays (saved by clicking with the same mouse button in the blink submenu button).

In Color mode, mouse dragging stretches and shifts the color map as per the contrast/bias, threshold/saturation, and \gamma submenu selections.

In the color graph window, color table vertexes may be added or moved by clicking or dragging with the LEFT (red), MIDDLE (green), or RIGHT (blue) mouse buttons. The graph will update continuously only if tracking is turned on.

In Cursor mode, the mouse controls the size and locations of cursors. The rule is: LEFT button for position, MIDDLE button for size, and RIGHT button for angle or deletion (depending on the cursor).


For box and ellipse cursors, MIDDLE button sizing is restricted depending on whether dragging started on a side or near a corner.

With the point cursor, the LEFT and MIDDLE buttons save the current mouse pointer position with a + or - indication, while the RIGHT button deletes saved points.

For the polygon cursor, the MIDDLE button adds or moves a single vertex, while the RIGHT button will delete vertexes. The LEFT button moves the whole polygon.

When annuli is set for a box, circle, or ellipse cursor, the MIDDLE button adds or resizes an annulus, while the RIGHT button deletes annuli.

For manipulating cursors, the ovlay selection in the Color submenu, enables the cursor to track smoothly as an overlay graphic. The region submenu button brings up another submenu with selections to display, review, and edit the saved regions, and read from or write to disk files.

Pan and zoom

In Pan mode, and in the pan window (regardless of mode), the LEFT button selects the center of the image, while the MIDDLE button selects the edge of the display, zoomed from the given center. When either function is dragged, the rectangle in the pan window shows the area that would appear in the display when the button is released.


In the cursor mode, the S and E keys, save the current cursor in a region list, while the D and DELETE keys can be used to forget a region. At any time, with the pointer in the display or pan windows, the T key prints a table of pixel values at the pointer position to stdout. The 4 arrow keys can be used for fine movement of the pointer in any window. The SHIFT and SHIFT LOCK keys will reverse the magnifier window, color graph window and coordinate tracking status. The N key summons the pop-up editor for new command input. The A key raises and redraws all of SAOimage's windows.