Image Cursor

The Image Cursor is a permanent tracking cursor available in every Image Window. The Image Cursor is used for locating centroid positions, measuring region statistics, and defining the limits of column and row profile plots. It's center coordinates, rectangle extent, and shape are used by many Mira commands for assessing, measuring, and plotting image data.

The Image Cursor is different from the mouse pointer which roams around the screen (see the picture below). There is only one Image Cursor per Image Window. Therefore, if an image set is opened by the window, the same Image Cursor is used for all members of the set. For example, if you use the Image Cursor to define the region to be cropped, and the Process Image Set flag is enabled, then all members of the image set will be cropped to the same region marked by the Image Cursor. Numerous keystroke commands work in concert with the Image Cursor to make measurements, create plots, and perform other operations in concert with the Image Cursor. See Image Window Keystroke Commands and Image Keys Pane.

The image cursor is dedicated to its image window and it stays fixed on the image unless you intentionally move it. It can be adjusted to any size and positioned anywhere within the image. See Adjusting the Image Cursor.

NOTE

When the Image Cursor is used to measure centroid positions for an Image Set, the cursor position may appear to be inaccurate after being shifted within the individual images. This happens because the Image Cursor is a feature of the Image Window rather than the individual images. However, the centroid coordinates tabulated in the measurement grid are correct. In contrast, Point Measurements are calculated and marked independently on each image, so they indicate the measured coordinates in each image if the centroid option is enabled on the Centroid Properties page.

The Image Cursor can be switched between 3 different shapes or hidden from view. You can select the shape using the Image Cursor Properties dialogs, Image Cursor Toolbar, or by using the (Cursor Mode) button on the Image Bar shown in the picture below.

Using the Image Cursor

Use the Ctrl+A keyboard shortcut to quickly switch the Image Cursor between Roam andCursor modes. See the Image Windows topic.
The Image Cursor position and edges are defined in terms of image pixel coordinates. Therefore, if you magnify the image, the Image Cursor coordinates remain correct at the level of sub pixel precision, independent of the way the image is displayed.
The Image Window Keystroke Commands topic describes the numerous keystroke measurement commands that work with the Image Cursor.
The Go To Coordinates command saves the Image Cursor coordinates or send the cursor to the provided coordinates.
The values of pixels in a rectangle around the Image Cursor center can be viewed in the Pixel Table Pane. The table updates as the cursor is moved.
The bounds and size of the Image Cursor are displayed for the current image using Status Bar space along the bottom border of the main Mira window frame, as shown below. These quantities are dynamically updated as you move or resize the cursor. This applies only to Image Windows and the information disappears if you hover the mouse over a Plot Window or 3-D Plot Window. The reason this information is displayed on the main window frame, rather than the Image Window frame itself, is so that it remains visible when the bottom of the Image Window is is hidden within the Mira application window.

Mouse Pointer vs. Image Cursor

The table below lists the differences between the capabilities of the Image Cursor and the Mouse Pointer.

Property	Mouse Pointer	Image Cursor
Tracking & Moving	Always moves with the mouse.	Moves only in Cursor Mode and when the mouse button is is down. Otherwise, remains where you drop it.
Size	Cannot be resized.	Resized by dragging the edges or by setting exact dimensions.
Dimensions	Fixed by icon size.	Measured in image pixel units (i.e., columns x rows).
Coordinates	Dynamically displays image x, y, column, row, and pixel value as it roams over the image.	Does not display coordinates. Measurements such as Centroid are listed in a Report Window or Measurement Pane.
Shape	Takes the shape of an icon for each different command or tool mode.	Can be changed to crosshair, rectangle, lines, or hidden. The rectangle also shows a central crosshair.
Position	Moved only by moving the mouse.	Moves using the mouse in Cursor Mode or using the keyboard arrow keys.

Using the Image Cursor

Mouse Pointer vs. Image Cursor

Related Topics