DIPimage User Manual » Toolbox Functions

The GUI: dipimage

The GUI is started with the dipimage command. It contains menus with the basic image-processing functions in the toolbox. After choosing any of these menu items, the GUI window transforms itself into a dialog box so that you can enter the appropriate parameters. The controls that allow entering images have a context-menu (obtained by right-clicking in them) with the names of the images currently defined. It is possible to enter the name of a variable containing an image or any valid MATLAB statement that evaluates to image data. (The same is true for other objects, like measurements or data-sets. Also, the window selection control, which is a drop-down list, can be updated through its context-menu.) Pressing the “Execute” button causes the function to be called. There is also a button to get help on the particular function.

In the “File I/O” menu is an option “Record macro”. When selected, the user is asked for the name under which the macro will be recorded. The extension will be “.m”, indicating it is an M-file. MATLAB scripts are M-files, and can be executed by typing their name on the command line. After entering the name (let’s assume we use the default “macro.m”), this file will be created (or appended to if it already exists), and loaded in the editor.

Any commands executed through the DIPimage GUI will be written to this file, in the same manner as that they are echoed to the command line. When finished, select the same menu item again (its text will have changed to “Stop recording macro”). Typing the macro name on the command line:


will execute all recorded commands again. It is possible to append commands to a recorded macro by starting the recording again with the same macro name. It is also possible to edit the macro in the editor. However, if you edit the macro file while recording, do remember to save your changes before executing another command through the GUI.

The dipshow function

dipshow shows a dip_image object in a figure window. It is the function that is called when leaving the semicolon off at the end of a MATLAB statement that returns a dip_image object (see Displaying dip_image objects). An optional second argument indicates the display range required, and allows more flexibility than the options in the “Display” menu. The general form for dipshow is:


where range is either a grey-value range that should be displayed, or one of 'log' or 'base'. A range is a numeric array with two values: a lower and an upper limit. The pixels with the same or a lower value than the lower limit will be mapped to black. The pixels that are equal or larger than the upper limit will be mapped to white. All other values are linearly spaced in between. The strings 'lin' and 'all' and the empty array are a shortcut for [min(image),max(image)], and cause the image to be stretched linearly. The string 'percentile' is a shortcut for [percentile(image,5) percentile(image,95)], and 'angle' and 'orientation' are equivalent to [-pi,pi] and [-pi,pi]/2 respectively. The default range is [0,255], which is used unless a range is given explicitly. colmap is a colormap. It can either be 'grey', 'periodic', 'labels' or an array with 3 columns such as those returned by the MATLAB functions hsv, cool, summer, etc. (see the help on colormap for more information on this).

The strings 'angle' and 'orientation' imply 'periodic' if no explicit colormap is given. This colormap maps both the maximum and minimum value to the same color, so as to hide a jump in angle or orientation fields. The string 'labels' implies a range of [0,255], and produces a colormap that gives each integer value a distinct color.

The string 'log' causes the image to be stretched logarithmically. 'base' is a linear stretch that fixes the value 0 to a 50% grey value.



If the input argument is a color image, it will be converted to RGB for display.

The image is displayed in a figure window according to the name of the variable that contains the image. Links can be made using the dipfig function (see Creating, linking and clearing figure windows: dipfig and dipclf). If the variable name is not registered, a new figure window is opened for the image. To overrule this behavior, it is possible to specify a figure handle in the parameter list of dipshow:


Finally, an optional argument allows you to overrule the default setting for the 'TrueSize' option. By adding the string 'truesize' at the end of the parameter list for dipshow, you can make sure that diptruesize is actually called. The string 'notruesize' does the reverse.

See Figure Windows for more information on the figure windows used by dipshow.

Figure window support: dipmapping

The function dipmapping can be used to change the image-to-display mapping. All menu items under the “Mappings” menu are equivalent to a call to dipmapping. In a single command, you can combine one setting for each of the four categories: range, colormap, complex-to-real mapping, the slicing direction and the global stretching for 3D images.


changes the mapping settings for the image in the figure window with handle h. It is not necessary to provide all four values, and their order is irrelevant. range can be any value as described for dipshow in The dipshow function: a two-value numeric array or a string. colmap can contain any of the strings described for dipshow, but not a colormap. To specify a custom colormap, use


torealstr can be one of 'abs', 'real', 'imag' or 'phase'.

slicingstr can be one of 'xy', 'xz', 'yz', 'xt', 'yt' or 'zt'.

globalstr can be one of 'global' or 'nonglobal'.

If you don’t specify a figure handle, the current figure will be used.

Additionally, you can specify a slice number. This is accomplished by adding two parameters: the string 'slice', and the slice number. These must be together and in that order, but otherwise can be combined in any way with any of the other parameters. The same is true for the 'colormap' parameter.

Note that this function applies only to figure windows created by dipshow.

Figure window support: diptruesize

The “Sizes” menu contains some options to call diptruesize (see The figure window menus). This function causes an image to be displayed with an aspect ratio of 1:1, each pixel occupying one screen pixel. An argument gives the zoom factor. For example, 200 would make the image twice as large on the screen, but with the 1-to-1 aspect ratio:


diptruesize('off') causes the image to fill the figure window, possibly loosing the aspect ratio. diptruesize accepts a figure handle as an optional first argument. If you provide a handle, you must also provide a zoom factor. See help diptruesize for other options not available through the figure window menu.

Note that this function applies only to figure windows created by dipshow.

Figure window support: diptest, dipzoom, et al.

As explained in The figure window menus, the the “Actions” menu contains items corresponding to the commands diptest, dipzoom, diplooking, dippan, diplink, dipstep, dipanimate, and dipisosurface. See the help for each of these functions (using the help command) to learn more about them.

Note that these functions apply only to figure windows created by dipshow.

Creating, linking and clearing figure windows: dipfig and dipclf

The single most important thing that can be customized in the DIPimage environment is the way that images are displayed to figure windows. It is possible to link a variable name with a figure handle, such that that variable is always displayed in that same window. If a variable is not linked to any window, a new one will be opened to display it. The command

dipfig a

opens a new figure window and links it to the variable named a. Whenever that variable (if it contains an image) is displayed, it will be send to that window. If the window is closed, it will be opened again to display the variable. It is possible to link more than one variable to the same window, like in the next example (which uses the functional form):

h = dipfig('a')

Finally, there is a special variable name, 'other', that creates a link for all variables not explicitly linked to a window. It is possible to have many windows linked to this special name, and they will be used alternately. Creating a window for 'other' avoids the opening of new windows for ‘unregistered’ variables.

To remove the links, type

dipfig -unlink

Unlinking only a specific variable is not implemented.

To clear all figure windows (for example at the beginning of a demo), use the function dipclf. It doesn’t change the position or size of any window, but removes the images in them. dipclf can also be used to clear selected windows by giving it an array with handles or a cell array with names as an argument (in a cell array you can actually combine numeric handles and variable names).

Note that these functions apply only to figure windows created by dipshow.

Toolbox preferences: dipsetpref and dipgetpref

All toolbox preferences are stored in memory, and are only accessible through the dipsetpref and dipgetpref functions. They are listed in Other settings.

v = dipgetpref('name');

retrieves the value of the named preference. Two special forms print all current preferences and all factory settings to the command window:

dipgetpref factory

Setting a preference is similar:


Furthermore, it is possible to set many preferences at once:


Interactive tools: dipgetcoords, diproi, et al.

These are some tools that, using an image display, allow the user to select points or regions in an image. dipgetcoords returns the coordinates of one or more points selected by clicking on an image.

diproi returns a mask image (ROI stands for region of interest) created by selecting the vertices of a polygon; it can only be used with 2D images.

dipcrop returns a rectangular portion of an image selected by dragging a rectangle. dipprofile returns a 1D image interpolated along a path selected by the user on the display.

dipgetimage retrieves the image from a display. Use it if you lost an image but can still see it in its display.

dipstackinspect lets the user click on a 3D display, and shows a 1D plot of the hidden dimension at that point. The tool will stay active until the right mouse button is clicked over the image.

Note that these functions apply only to figure windows created by dipshow.

Image processing functions

The largest part of the toolbox is made out of the image processing functions. Most of them are listed in the menu system of the GUI, and all are listed by typing

help DIPimage

The usage of each function can be retrieved through the help command or through the GUI.