Locate all contours of a specific intensity level within a window and plot the actual contours onto a specified buffer. The contours may be filtered on contour length so that only those contours longer than a certain limit will be plotted; if this option is chosen, better results will be obtained if the [I Remove small islands] filter is first applied to the image (see the help for this option for more details).
This option uses the same kernal as [C Contours]. The difference lies in that only the first contour found satisfying the minimum length criterion is used. The location of the contour will be transformed automatically to the pixel and world reference coordinate systems, as appropriate, and written to an optional file. The contour located may either be from an organised search of the window or entire buffer, or from a single point provided by the cursor. In some circumstances, better results will be obtained if the [I Remove small islands] filter is first applied to the image (see the help for this option for more details).
By specifying a starting point and limiting contour intensity, the entire region within a certain contour may be filled with with a particular intensity. The purpose of this feature is primarily to allow a mask buffer to be set up, based on an intensity contour. This mask buffer may be used subsequently in conjunction with the ALU to select specific regions of an image for further processing.
This option locates a contour passing through a user-specified point. The coordinates of this contour are then expressed in terms of the distance along the contour, s, and a least squares fit is generated for this data.
This option provides access to a filter designed specifically to remove features from the image which will produce short contours due to their small area. The principle is to remove islands or blobs to either side of the specified threshold if they have an area less than a specified value. Unlike convolution filters, the sharpness of the edges is not affected. While the contouring options [C Contours] and [E Locate edge in window] are able to select only contours longer than a specified minimum length, the result of doing this may lead to contours appearing open even though they are closed in some circumstances. If only long contours are required, then this filter should be applied to the image before locating the contours.
Trace along a parametrically defined curve, sampling the intensities. These intensities will then be displayed graphically as a function of the controlling parameter.
A contour mask buffer provides a method for selecting certain nonrectangular regions of the image for processing. On completion the mask buffer contains a binary image representing the large scale features of the source buffer relative to some uniform threshold.
Once created, the contour mask buffer may be used in conjunction with an image buffer by logical ALU operations or the <f8> masking facility to mask off either the high or low intensity regions and so produce an image containing only the required information.
This option lets the user create a file containing a list of interactively obtained points. In addition, the file may contain associated user-specified information (which may be either character or numeric, up to 80 characters in length) for each point.
This option starts the cursor menu in intensity section mode where the intensities in the line and column specified by the cursor are displayed graphically.
The purpose of this option is to take the intensity field within a user-specified window and transform it into a 3D surface plot using a wire frame model (with or without hidden surface removal).