The aim of this tool, is to allow the observation in full scale of a part of an image which can't be displayed on a screen in full scale, because of its too large size (zoom values < 100%), without using the Zoom +/- or the Scrolling tool functions. It works on all ImageJ image format including stacks. The tool contains a cursor allowing a precise location to obtain the pixel coordinates.

Select the tool on the tool bar, and draw a cursor on an image by keeping clicked and moving the mouse cursor to the desire location. When unclick, a view of the cursor delimited area is displayed on the bottom left of the screen. Obtain the coordinates of the cursor target pixel and of the tool image selection, by choosing Macros -> Display Coordinates in the Plugins menu.

A fine pointing is allowed by the keypad along vertical and horizontal axes, and the diagonals. On notebooks, use the pseudo keypad of the keyboard, accesible by the "function" key. Moving by keeping down a key of the keypad, needs a fast computer, and depends on the system (§2). If it is too slow, prefere several clicks instead of a keeping down. The keypad associated functions are not yet avaible when the tool is unselected.

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The default size can be changed by a double click on the tool bar icon. There are two ways to make this changing affective:

- by modifying an existing cursor; first click on the title bar of the image containing cursor to select it, before changing the size.

- by using the tool and drawing a new cursor.

Set the default size to an existing cursor size:

It is possible to work with several images containing different cursor sizes. The use of the tool with the mouse, resizes the cursor to the current size setting. To reuse an existing cursor size in an image, different to the current size setting, activate the image containing cursor by clicking in its title bar, and use a keypad move function. The new default size is then automatically reset to this of the existing cursor.

§1 The Magnifying Glass Tool is avaible in the IJ macros tools repertory at http://rsb.info.nih.gov/ij/macros/tools/ManifyingGlassTool.txt

ImageJ (http://rsb.info.nih.gov/ij/) is a public domain Java image processing program inspired by NIH Image for the Macintosh. It runs, either as an online applet or as a downloadable application, on any computer with a Java 1.1 or later virtual machine. Downloadable distributions are available for Windows, Mac OS, Mac OS X and Linux. The author, Wayne Rasband (wayne@codon.nih.gov), is at the Research Services Branch, National Institute of Mental Health, Bethesda, Maryland, USA.

§2 With MacOS X3, the keeping down mode of the keypad associated moves works correctly, with MacOS X4.3, it's sometime jerky, on Win XP, it makes sometimes flash the Desktop.