imodauto(1)                                                        imodauto(1)



NAME
       imodauto - creates a model from an mrc image stack.

SYNOPSIS
       imodauto  [options]  MRC_image_file  output_model_file

DESCRIPTION
       imodauto creates an IMOD model from an MRC image stack using a simple
       image thresholding.  Both a low and a high threshold may be set; con-
       tours are drawn around groups of pixels that are below the low thresh-
       old and around pixels above the high threshold.  Image data are read
       from the file and scaled to values between 0 and 255, just as when
       reading into 3dmod.  The thresholds may be specified as values
       either before or after this scaling.  In addition, thresholds may be
       specified as absolute values or as multiples of the mean image inten-
       sity.  The default behavior is for thresholds to be interpreted as
       absolute values after scaling, in which case they will correspond to
       thresholds set in the 3dmod autocontouring window.

       Typically, you would enter either a low or a high threshold, but not
       both.  However, if your images have annular regions of pixels, you can
       get contours drawn both inside and outside the regions by having the
       same value for the low and the high threshold.  The details of making
       this work right are handled by the -n option.  Using that option, you
       would enter the threshold once, as either a low or a high threshold,
       depending on whether the features of interest are dark or light.  The
       program will set the other threshold equal to the given one, and follow
       diagonals (connect pixels touching only on their corners) and eliminate
       contours touching edges as appropriate.  For example, if you enter a
       high threshold, then imodauto will follow diagonals when finding areas
       above threshold, but not when finding areas below threshold.  This sub-
       tlety is needed to achieve sensible nested contours.  In this example,
       the program will also eliminate any contours touching the edges of the
       image area when finding areas below threshold; otherwise a large con-
       tour enclosing most of the image would be produced.

       Imodauto can also be used to make contours around areas containing a
       particular uniform value, regardless of the values of neighboring pix-
       els.  This feature is useful if an image volume has already been seg-
       mented by other means to produce a volume in which different regions
       are marked with one or more values.  Use the -E option to specify an
       exact value to generate contours around.  The value may be a scaled
       value, as read out of 3dmod, or it may be the actual value in the
       file if the -u option is used.  The -f option can be used to follow
       diagonals, but 3 is the only meaningful value.  Inside contours can be
       found with the -n option.  One problem with the model output is that it
       will be appear jagged as it follows the edges of pixels, since the
       interpolation method used with normal image data is assumed to be mean-
       ingless and is not applied.  There are three tools available for get-
       ting a smoother model.  1) Use the -R option with a value of 0.5 to
       remove all points within 0.5 pixel of the remaining lines.  This method
       will still leave some jaggedness but contours will still follow the
       edges of the region fairly well.  2) Use Smoothsurf solely to smooth
       the contours in 2D by entering parameters such as:
            smoothsurf -nz 1 -dist 3 -cont 3
       This may produce smoother output than the first method, but may deviate
       more from the region at sharp corners.  3) Use the contour smoothing
       option in Drawing Tools, available from the Special menu of 3dmod.
       Check the option to "ALLOW POINTS TO BE MOVED" and reduce the "min dis-
       tance to move" to 0.1.  This may be the best method.

OPTIONS
       -l value
              Specifies the low threshold level.  Contours will be generated
              around pixels that map to levels below the low threshold level.
              The default value is 0, which will give no contours for areas
              below threshold.

       -h value
              Specifies the high threshold level.  Contours will be generated
              around pixels that map to levels above the high threshold level.
              The default value is 255, which will give no contours for areas
              above threshold.

       -E value
              Specifies an exact value to generate contours around, regardless
              of whether surrounding pixels are high or lower than this (see
              discription above).  The -l, -h, and -d options may not be
              entered together with this option.

       -d value
              Determines how the low and high threshold levels are computed.
              The default value is d = 1, in which case the low and high val-
              ues are used directly.  When d = 2, the high and low values are
              treated as factors to be applied to the mean of the image file
              (after loading into the program).  If an image file's mean value
              is 50 and the low value is 0.5 then the low threshold will be
              set to 25.  When d = 3, the low and high values are factors
              applied to the mean of each individual section.

       -u     Specifies that the entered threshold values are to be inter-
              preted as unscaled, corresponding to the actual values in the
              image file.  By default, threshold values are instead inter-
              preted as scaled values to be applied after the images are
              scaled to the range of 0 to 255.

       -f value
              Determines whether diagonals are followed when finding groups of
              connected pixels.  The default value is 0, meaning that diago-
              nals will not be followed.  With a value of 3, diagonals will
              always be followed.  With 1 or 2 diagonals will be followed only
              for areas above the high threshold or below the low threshold,
              respectively.

       -n     Find inside contours in closed, annular regions.  To use this
              option, enter one threshold as appropriate for defining your
              regions of interest.

       -m value
              Minimum area for each contour, in square pixels.  Any values
              less than 1 will be treated as 1.  The default value is 10.

       -M value
              Maximum area for each contour, in square pixels.  If this option
              is not used, no maximum size will be enforced.  Any value
              entered should be greater than the minimum area specified by -m.

       -e value
              Criterion for eliminating contours based on the number of edges
              of the image that they touch.  Values from 1 to 4 are meaning-
              ful; for example, a value of 2 will eliminate contours that
              touch 2 or more edges.  The default is zero, for no selection on
              the basis of edges touched.

       -r value
              Resolution for point shaving, in which points are removed when
              they are closer than the given distance apart.  This method of
              point removal will eliminate some detail and might be useful for
              smoothing; otherwise, the -R option is preferable.  The default
              value is 0.0, which turns this feature off.

       -R value
              Resolution or tolerance for point reduction when generating the
              final model.  Points are eliminated if they are within this
              distance of the lines connecting the remaining points, just as
              with the -R option in imodmesh and the resolution feature
              when autocontouring in 3dmod.  This method of point removal
              will preserve detail as well as possible, unlike the -r option.
              Values in the range 0.25 to 0.5 are often useful.  The default
              value is 0.0, which turns this feature off.

       -s min,max
              Set the intensity scaling for the image data, so that min is
              mapped to 0 and max is mapped to 255.  The default for these
              values are the minimum and maximum from the image file header.

       -X min,max
              Load and model a subset in X from min to max, where the coordi-
              nates are numbered from 0.

       -Y min,max
              Load and model a subset in Y from min to max, where the coordi-
              nates are numbered from 0.  If the -e option is used with -X or
              -Y, then decisions about contours are made based on the edges of
              the loaded subset of the image, not of the full image.

       -Z min,max
              Load and model a subset in Z from min to max, where the coordi-
              nates are numbered from 0.

       -B filename
              Specify a model with boundary contours around the region(s) to
              be modeled.  These contours should all be in one closed contour
              object.  More than one contour can be drawn on each section.  By
              default, when there are any boundary contours, each section will
              use the contours on the nearest sections; thus, only one or a
              few contours may be needed.  Use -e 1 to eliminate contours that
              touch the boundaries.  There is one flaw in this elimination if
              inside contours are being found: inside contours may be produced
              that are no longer surrounded by an outer contour, because the
              outer contour was eliminated while the inner ones were retained.

       -S     Apply the boundary contours only on the same sections as they
              are drawn; sections without boundary contours will be analyzed
              in their entirety.

       -O value
              Specify the object number that contains boundary contours in the
              boundary model.  By default, the program will use the first
              closed contour object in the model.

       -k sigma
              Smooth the data with a kernel filter whose Gaussian sigma is
              given by the entered value.  This filter is the same as the
              smoothing filter in the 3dmod image processing window or in
              Clip.  Use a value of 0 to select the simple default filter
              instead of the Gaussian kernel.

       -z value
              Set the zscale for the model.  The zscale is a factor that com-
              pensates for 3 dimensional data that is sampled at a different z
              resolution than the x-y plane data.  If the images have 25nm
              pixels and 100nm z slice size then the z-scale factor would be
              4.0.

       -c r,g,b
              Set the color of the model object by specifying red, green, blue
              values separated by commas.  The values can range from 0 to 1 or
              from 0 to 255; i.e., 1.0,0.5,0 and 255,128,0 could both be used
              to specify orange.

       -x     Expand areas by one pixel before enclosing them in contours,
              just as in 3dmod autocontouring.

       -i     Shrink areas by one pixel before enclosing them in contours,
              just as in 3dmod autocontouring.

       -o     Smooth areas before enclosing them in contours.  As in 3dmod
              autocontouring, this is implemented by expanding then shrinking.

       The segmentation used by imodauto is a simple threshold.  Each pixel
       lying between the low and high thresholds is thrown out.  Then, the
       program finds all of the separate areas lying below the low or above
       the high threshold.  Groups of pixels with area greater then the value
       given by the -M option or area less then the value given by the -m
       option are thrown out.  Next, contours are drawn around each remaining
       area.

       If the -r option has a value greater than 0, then points are eliminated
       from each contour if they are less than the given distance apart.
       After that, if the -R option has a value greater than 0, points are
       eliminated if they are within the given distance from the lines between
       remaining points.

FILES
       If the model file already exists, it becomes a backup file with ~ added
       to its name.

AUTHORS
       Jim Kremer and David Mastronarde

SEE ALSO
       3dmod, 3dmodv, imodmesh, contourmod

BUGS
       Email bug reports to mast at colorado dot edu.



BL3DEMC                              4.7.3                         imodauto(1)