imodauto(1) imodauto(1) NAME imodauto - creates a model from an mrc image stack. SYNOPSIS imodauto [options] <MRC image file> <IMOD 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- touring enclosing most of the image would be produced. 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. -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 dis- tance 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. Val- ues 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. -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 4.3.7 imodauto(1)