The input file containing the data to be displayed as a zoom is monitored by default; the file is checked every 2 seconds for change, and if it has been modified, the zoom display is updated accordingly. The interval at which the input file is checked for modification may be specified using the [-update] argument.
A clip mask may be used to dictate the portion of the data that is displayed using the [-clip] argument. For more information of using clip masks, see Chapter 4 on Editimage.
An alternate input color map may be used to change the current color map using the [-cmap] argument.
The x and y coordinates that specify where the zoomed image focuses within the source image can be expressed using the [-zoomx] and [-zoomy] arguments.
It is possible to specify the zoom factor using the [-zoomfactor] argument. When the zoom factor takes on values greater than one, the object is "zoomed in" and when the zoom factor takes on values less than one, the object is "zoomed out". For example, a value of 2.0 doubles the size of the image, while a value of 0.5 shrinks the image by half. The zoom factor is intentionally a double precision value; this means that in the case of pixel replication, pixels are rounded to their nearest location. This also implies that under certain circumstances, the zoom will not appear to stretch evenly over the entire image.
By default, the visualization display will share its colormap with all other applications running at the same time; that is, it does not not use a private colormap, but rather makes use of the default colormap. It is possible to specify that the visualization display allocate its own private colormap or "grab" all available colors for its own use. This is done using the [-priv] argument. When [-priv] is specified, moving the mouse pointer into the display window will cause the display to have its private colormap installed; moving the pointer out of the display window will cause the private colormap to be de-installed. This results in the "technoflashing" phenomenon characteristic of colormap switching.
Color allocation can also be controlled and set to either "read-only" or "read/write" using the [-alloc] argument. When set to "read-only", once a color cell has been allocated, it can have its color set only once; from then on, the color cell can be shared by multiple applications, but not changed. If the visualization display requires the color displayed to change, it must re-allocate the color cell, forcing a re-display of data. This can be an expensive procedure. In contrast, after a "read/write" color cell is allocated, it can have its color changed at any time without re-allocation; the data being displayed does not need to be redisplayed, and the color update process is much more efficient. However, the colors used in the visualization display cannot be shared by other applications.
On creation, the zoom display window may be placed manually (the default method), or placed automatically. For automatic placement of the zoom window, specify the desired location in device (screen) coordinates using the [-x] and [-y] arguments.
While the zoom display window should be created with a default size that is appropriate to display the data, a width and height for the window can be specified explicitly using the [-width] and [-height] arguments. Note that interactive resizing of the image display window using the window manager is currently NOT supported.
% putzoom -i image:mandril
% putzoom -i image:moon