Clicking on the View button opens a new window, which serves as a control center for all the displays (graphs + images) you might want to have. This window is composed of four sub-windows : Figure, Image mode, Tools, and finally a originally blank region which will contain the list of all opened figures along with the data displayed in each figure. This list allows you to select which figure or signal is currently active by clicking on it. Only the active element will be affected by the various commands available in the other sub-windows of the View menu.
It is important to understand the difference between a View and the data displayed in it. A View corresponds to a Matlab figure that will display one or several graphs or images. The case of several graphs corresponds to the use of the sub-plot command in Matlab. Since, in the case of multiple plots, you might want to apply a different processing to each sub-plot, you need to tell Fraclab which sub-plot is the current one. This is why the list at the bottom of the View window will show the name of all the opened views (i.e. Matlab figures) numbered in the chronological order of their appearance, and, for each of these views, the name of the signals that are shown in this figure as plots or sub-plots. This will allow you to select either a whole figure or one of its sub-plot. For instance, some viewing options such as hold, rotate or zoom are available only when a particular signal is highlighted, and are grayed out when the whole view is highlighted. Note finally that clicking in the list either on a view or on one of the signals that it contains will bring the corresponding window to the foreground, a useful feature if you have many opened windows or/and if you do not remember which signal is which.
view in new : opens a new figure which will display the highlighted data in the Variables zone of the main window.
view : displays the highlighted variable in the current figure, i.e. the one which is highlighted in the figures list. Depending on whether the hold button in the Tools sub-window is selected or not, pressing view will replace the current plot or will be placed on top of it.
close all : Usually, you will probably find it more convenient to keep the View window opened at all time. However, pressing this button will close all figures, control panels and toolbar.
This menu is active only when an image is selected in the list, and is grayed out when either a view is selected (because Fraclab needs to know which image must be processed and not merely which view is the current one) or a 1D signal is currently active (indeed, the processings in this sub-window make no sense for 1D signals).
image control opens the image control panel (note that image control is grayed out when the image control panel is already displayed). This panel first recalls which data is being processed in the plot line.
The mode button then allows to choose how the data should be displayed : as an image, a contour plot, a mesh, a surface, or as a superposition of 1D signals which might be its lines or columns. In addition, a particular line/column might be selected for display.
colormap selects a color map for the display.
dynamic allows to toggle between a linear and a logarithmic dynamic for both the numerical and graphical display of the data.
min level, max level : these boxes allows you to enter the interval in which the data must fall in order to be displayed. Pixels with grey levels outside this range will be clipped.
value governs the way the data are numerically displayed, for instance in the min level and max level boxes, or in the get point box : normalized will forces the output to be between 0 and 1, while true causes the real values to be displayed
display toggles between a normalized and a true display for the grey levels in the image.
binary displays all the pixels with grey level between min level and max level in white and all others in black.
reverse revert the order of the color map. This is particularly useful in conjunction with binary to toggle between "in" and "out" pixels.
get point : pressing this button will bring the image figure to the foreground and display a cross that you may center at any point. Clicking will cause Fraclab to display the coordinates of the chosen point along with its grey level in the box to the right. Whether the displayed grey level will be the true one, a normalized one, or a binary one depends on the choices described above. Note that it is possible to zoom in the image before activating get point to gain more precision. As said in the Message line of the main window, press Enter in the image to get out of this mode, or click again on get point.
axis : toggles the aspect ratio between the true axis of the image and the Matlab default.
x axis - y axis : enables to load a new array to use as axes, when the data are displayed as anything but an image.
Note that the chosen modifications do not result in an immediate update of the display. Rather, you need to press Apply to see the effects of your choices.
The second button in Image mode is superpose. This allows to lay an image on the top of another one with a control of the "transparency". This works like a kind of hold facility for images, with additional functionalities. The main purpose of this is to compare an original image with e.g. its segmented version. More generally, you'll find this feature helpful when you need to compare two images one of which (at least) is "sparse" (like is a image of contours). Note however that you may perfectly use it for any kinds of images, for instance to compare consecutive images in a sequence. In practice, this is what you do: first display an image and select it in the views list. The superpose button should now be clickable. Select another image in the Variables list of the main window and press view. A new window titled Superpose Parameters appears, that allows to choose two parameters : the lut ratio decides how many entries in the current color map will be available for each image, while the threshold parameter controls the "amount" of each image that will actually be displayed. Let us detail this a little bit: The lut ratio may be varied between 0.5 and 1, i.e. the first image will used between one half and the whole of all available colors (or grey levels). Of course, when lut ratio = 1, you will not see the second image. Assume to simplify that your color map has 100 entries and that lut ratio = 0.8. Then prior to displaying, the first image will have its grey levels linearly re-mapped between 0 and 80, and the second one between 80 and 100. Second, if threshold is 0, only the second image will be displayed, while if threshold is 1 - lut ratio (this is the maximum possible value), you'll see only the first image. Setting threshold between these extremes allows you to balance the relative strength of the two images. Choose values for the lut ratio and the threshold and press Apply to see the effects of your selections. Experiment with other values until you are happy with the result. You may then Close the Superpose Parameters window.
Two known bugs of the superpose mode are the following: when you press Apply, the scalings of the axes are changed to the default matlab aspect ratio. Second, if you de-select superpose, the Superpose Parameters window does not close. This would not be a problem, except that it will yield an error next time you will press the Apply button. Thus, when you de-select superpose, remember to close also the Superpose Parameters window.
hold causes the current plot to be held, so that subsequent graphs are displayed on top of it.
rotate interactively rotates the view of a plot.
zoom allows to zoom on the current plot or image by selecting a region with the mouse.
Vsplit performs a vertical split of the figure in as many sub-plots as are specified in the box to the right. Hsplit does the same for horizontal sub-plots. Thus, to have a figure with m horizontal sub-plots and n vertical sub-plots, enter m in the Hsplit box, n in the Vsplit box, select one by one the desired graphs in the Variables window and press each time view : the data will be displayed sequentially in the corresponding sub-plots.
Pressing axes opens the axes control panel which allows to set up various parameters : the Scale type chooses between linear, semi-logarithmic or bi-logarithmic plots, the X range and Y range decides which parts of the data are to be displayed. For 1D signals, various Aspect parameters can be specified :
mark changes the symbol used to draw the computed points, line selects the symbol used to draw lines between the computed points, color defines the color of the plot, width controls the width of the line. Finally, the boxes red - green - blue allows to finely adjust the color of the line.
print opens the print control panel that allows to save the figure or print it with various options.
close figure closes the selected view and all its sub-plots.