Register, convert, warp, or manipulate images
plastimatch command [options]
The plastimatch executable is used for a variety of operations, including image registration, image warping, image resampling, and file format conversion. The form of the options depends upon the command given. The list of possible commands can be seen by simply typing "plastimatch" without any additional command line arguments:
$ plastimatch plastimatch version 1.5.12-beta (4019) Usage: plastimatch command [options] Commands: add adjust average crop compare compose convert dice diff dvh fill header jacobian mask probe register resample scale segment stats synth synth-vf thumbnail union warp xf-convert For detailed usage of a specific command, type: plastimatch command
The add command is used to add one or more images together and create an output image. The contributions of the input images can be weighted with a weight vector.
The command line usage is given as follows:
Usage: plastimatch add [options] input_file [input_file ...]
Options:
--average produce an output file which is the average of the
input files (if no weights are specified), or
multiply the weights by 1/n
--output <arg> output image
--weight <arg> specify a vector of weights; the images are
multiplied by the weight prior to adding their
values
To add together files 01.mha, 02.mha and 03.mha, and save the result in the file output.mha, you can run the following command:
plastimatch add --output output.mha 01.mha 02.mha 03.mha
If you wanted output.mha to be 2 * 01.mha + 0.5 * 02.mha + 0.1 * 03.mha, then you should do this:
plastimatch add \ --output output.mha \ --weight "2 0.5 0.1" \ 01.mha 02.mha 03.mha
The adjust command is used to adjust the intensity values within an image. The adjustment operations available are truncation and linear scaling.
The command line usage is given as follows:
Usage: plastimatch adjust [options]
Required:
--input <arg> input directory or filename
--output <arg> output image
Optional:
--pw-linear <arg> a string that forms a piecewise linear map from
input values to output values, of the form
"in1,out1,in2,out2,..."
The adjust command can be used to make a piecewise linear adjustment of the image intensities. The --pw-linear option is used to create the mapping from input intensities to output intensities. The input intensities in the curve must increase from left to right in the string, but output intensities are arbitrary.
Input intensities below the first pair or after the last pair are transformed by extrapolating the curve out to infinity with a slope of +1. A different slope may be specified out to positive or negative infinity by specifying the special input values of -inf and +inf. In this case, the second number in the pair is the slope of the curve, not the output intensity.
The following command will add 100 to all voxels in the image:
plastimatch adjust \ --input infile.nrrd \ --output outfile.nrrd \ --pw-linear "0,100"
The following command does the same thing, but with explicit specification of the slope in the extrapolation area:
plastimatch adjust \ --input infile.nrrd \ --output outfile.nrrd \ --pw-linear "-inf,1,0,100,inf,1"
The following command truncates the inputs to the range of [-1000,+1000]:
plastimatch adjust \ --input infile.nrrd \ --output outfile.nrrd \ --pw-linear "-inf,0,-1000,-1000,+1000,+1000,inf,0"
The average command is used to compute the (weighted) average of multiple input images. It is the same as the plastimatch add command, with the --average option specified. Please refer to plastimatch add for the list of command line arguments.
The following command will compute the average of three input images:
plastimatch average \ --output outfile.nrrd \ 01.mha 02.mha 0.3.mha
The autolabel command is an experimental program the uses machine learning to identify the thoracic vertibrae in a CT scan.
The command line usage is given as follows:
Usage: plastimatch autolabel [options]
Options:
-h, --help Display this help message
--input <arg> Input image filename (required)
--network <arg> Input trained network filename (required)
--output <arg> Output csv filename (required)
The crop command crops out a rectangular portion of the input file, and saves that portion to an output file. The command line usage is given as follows:
Usage: plastimatch crop [options]
Required:
--input=image_in
--output=image_out
--voxels="x-min x-max y-min y-max z-min z-max" (integers)
The voxels are indexed starting at zero. In other words, if the size of the image is M \times N \times P, the x values should range between 0 and M-1.
The following command selects the region of size 10 \times 10 \times 10, with the first voxel of the output image being at location (5,8,12) of the input image:
plastimatch crop \ --input in.mha \ --output out.mha \ --voxels "5 14 8 17 12 21"
The compare command compares two files by subtracting one file from the other, and reporting statistics of the difference image. The two input files must have the same geometry (origin, dimensions, and voxel spacing). The command line usage is given as follows:
Usage: plastimatch compare image_in_1 image_in_2
The following command subtracts synth_2 from synth_1, and reports the statistics:
$ plastimatch compare synth_1.mha synth_2.mha MIN -558.201904 AVE 7.769664 MAX 558.680847 MAE 85.100204 MSE 18945.892578 DIF 54872 NUM 54872
The reported statistics are interpreted as follows:
MIN Minimum value of difference image AVE Average value of difference image MAX Maximum value of difference image MAE Mean average value of difference image MSE Mean squared difference between images DIF Number of pixels with different intensities NUM Total number of voxels in the difference image
The compose command is used to compose two transforms. The command line usage is given as follows:
Usage: plastimatch compose file_1 file_2 outfile
Note: file_1 is applied first, and then file_2.
outfile = file_2 o file_1
x -> x + file_2(x + file_1(x))
The transforms can be of any type, including translation, rigid, affine, itk B-spline, native B-spline, or vector fields. The output file is always a vector field.
There is a further restriction that at least one of the input files must be either a native B-spline or vector field. This restriction is required because that is how the resolution and voxel spacing of the output vector field is chosen.
Suppose we want to compose a rigid transform (rigid.tfm) with a vector field (vf.mha), such that the output transform is equivalent to applying the rigid transform first, and the vector field second.
plastimatch compose rigid.tfm vf.mha composed_vf.mha
The convert command is used to convert files from one format to another format. As part of the conversion process, it can also apply (linear or deformable) geometric transforms to the input images. In fact, convert is just an alias for the warp command.
The command line usage is given as follows:
Usage: plastimatch convert [options]
Options:
--algorithm <arg> algorithm to use for warping, either
"itk" or "native", default is native
--ctatts <arg> ct attributes file (used by dij warper)
--default-value <arg> value to set for pixels with unknown
value, default is 0
--dif <arg> dif file (used by dij warper)
--dim <arg> size of output image in voxels "x [y z]"
-F, --fixed <arg> fixed image (match output size to this
image)
-h, --help display this help message
--input <arg> input directory or filename; can be an
image, structure set file (cxt or
dicom-rt), dose file (dicom-rt,
monte-carlo or xio), dicom directory, or
xio directory
--input-cxt <arg> input a cxt file
--input-dose-ast <arg> input an astroid dose volume
--input-dose-img <arg> input a dose volume
--input-dose-mc <arg> input an monte carlo volume
--input-dose-xio <arg> input an xio dose volume
--input-ss-img <arg> input a structure set image file
--input-ss-list <arg> input a structure set list file
containing names and colors
--interpolation <arg> interpolation to use when resampling,
either "nn" for nearest neighbors or
"linear" for tri-linear, default is
linear
--metadata <arg> patient metadata (you may use this
option multiple times)
--origin <arg> location of first image voxel in mm "x y
z"
--output-colormap <arg> create a colormap file that can be used
with 3d slicer
--output-cxt <arg> output a cxt-format structure set file
--output-dicom <arg> create a directory containing dicom and
dicom-rt files
--output-dij <arg> create a dij matrix file
--output-dose-img <arg> create a dose image volume
--output-img <arg> output image; can be mha, mhd, nii,
nrrd, or other format supported by ITK
--output-labelmap <arg> create a structure set image with each
voxel labeled as a single structure
--output-pointset <arg> create a pointset file that can be used
with 3d slicer
--output-prefix <arg> create a directory with a separate image
for each structure
--output-prefix-fcsv <arg>
create a directory with a separate fcsv
pointset file for each structure
--output-ss-img <arg> create a structure set image which
allows overlapping structures
--output-ss-list <arg> create a structure set list file
containing names and colors
--output-type <arg> type of output image, one of {uchar,
short, float, ...}
--output-vf <arg> create a vector field from the input xf
--output-xio <arg> create a directory containing xio-format
files
--patient-id <arg> patient id metadata: string
--patient-name <arg> patient name metadata: string
--patient-pos <arg> patient position metadata: one of
{hfs,hfp,ffs,ffp}
--prune-empty delete empty structures from output
--referenced-ct <arg> dicom directory used to set UIDs and
metadata
--simplify-perc <arg> delete <arg> percent of the vertices
from output polylines
--spacing <arg> voxel spacing in mm "x [y z]"
--version display the program version
--xf <arg> input transform used to warp image(s)
--xor-contours overlapping contours should be xor'd
instead of or'd
The first example demonstrates how to convert a DICOM volume to NRRD. The DICOM images that comprise the volume must be stored in a single directory, which for this example is called "dicom-in-dir". Because the --output-type option was not specified, the output type will be matched to the type of the input DICOM volume. The format of the output file (NRRD) is determined from the filename extension.
plastimatch convert \ --input dicom-in-dir \ --output-img outfile.nrrd
This example further converts the type of the image intensities to float.
plastimatch convert \ --input dicom-in-dir \ --output-img outfile.nrrd \ --output-type float
The next example shows how to resample the output image to a different geometry. The --origin option sets the position of the (center of) the first voxel of the image, the --dim option sets the number of voxels, and the --spacing option sets the distance between voxels. The units for origin and spacing are assumed to be millimeters.
plastimatch convert \ --input dicom-in-dir \ --output-img outfile.nrrd \ --origin "-200 -200 -165" \ --dim "250 250 110" \ --spacing "2 2 2.5"
Generally speaking, it is tedious to manually specify the geometry of the output file. If you want to match the geometry of the output file with an existing file, you can do this using the --fixed option.
plastimatch convert \ --input dicom-in-dir \ --output-img outfile.nrrd \ --fixed reference.nrrd
This next example shows how to convert a DICOM RT structure set file into an image using the --output-ss-img option. Because structures in DICOM RT are polylines, they are rasterized to create the image. The voxels of the output image are 32-bit integers, where the i^th bit of each integer has value one if the voxel lies with in the corresponding structure, and value zero if the voxel lies outside the structure. The structure names are stored in separate file using the --output-ss-list option.
plastimatch convert \ --input structures.dcm \ --output-ss-img outfile.nrrd \ --output-ss-list outfile.txt
In the previous example, the geometry of the output file wasn't specified. When the geometry of a DICOM RT structure set isn't specified, it is assumed to match the geometry of the DICOM CT image associated with the contours. If the associated DICOM CT image is in the same directory as the structure set file, it will be found automatically. Otherwise, we have to tell plastimatch where it is located with the --dicom-dir option.
plastimatch convert \ --input structures.dcm \ --output-ss-img outfile.nrrd \ --output-ss-list outfile.txt \ --dicom-dir ../ct-directory
The plastimatch dice compares binary volumes using Dice coefficient, Hausdorff distance, or contour mean distance. The input images are treated as boolean, where non-zero values mean that voxel is inside of the structure and zero values mean that the voxel is outside of the structure.
The command line usage is given as follows:
Usage: plastimatch dice [options] reference-image test-image
Options:
--all Compute Dice, Hausdorff, and contour mean distance
(equivalent to --dice --hausdorff --contour-mean)
--contour-mean Compute contour mean distance
--dice Compute Dice coefficient (default)
--hausdorff Compute Hausdorff distance and average Hausdorff
distance
-h, --help display this help message
--version display the program version
The following command computes all three statistics for mask1.mha and mask2.mha:
plastimatch dice --all mask1.mha mask2.mha
The plastimatch diff command subtracts one image from another, and saves the output as a new image. The two input files must have the same geometry (origin, dimensions, and voxel spacing).
The command line usage is given as follows:
Usage: plastimatch diff image_in_1 image_in_2 image_out
The following command computes file1.nrrd minus file2.nrrd, and saves the result in outfile.nrrd:
plastimatch diff file1.nrrd file2.nrrd outfile.nrrd
This command is under construction.
The dvh command creates a dose value histogram (DVH) from a given dose image and structure set image. The command line usage is given as follows:
Usage: plastimatch dvh [options]
--input-ss-img file
--input-ss-list file
--input-dose file
--output-csv file
--input-units {gy,cgy}
--cumulative
--num-bins
--bin-width
The required inputs are --input-dose, --input-ss-img, --input-ss-list, and --output-csv. The units of the input dose must be either Gy or cGy. DVH bin values will be generated for all structures found in the structure set files. The output will be generated as an ASCII csv-format spreadsheet file, readable by OpenOffice.org or Microsoft Excel.
The default is a differential (standard) histogram, rather than the cumulative DVH which is most common in radiotherapy. To create a cumulative DVH, use the --cumulative option.
The default is to create 256 bins, each with a width of 1 Gy. You can adjust these values using the --num-bins and --bin-width option.
To generate a DVH for a single 2 Gy fraction, we might choose 250 bins each of width 1 cGy. If the input dose is already specified in cGy, you would use the following command:
plastimatch dvh \ --input-ss-img structures.mha \ --input-ss-list structures.txt \ --input-dose dose.mha \ --output-csv dvh.csv \ --input-units cgy \ --num-bins 250 \ --bin-width 1
The fill command is used to fill an image region with a constant intensity. The region filled is defined by a mask file, with voxels with non-zero intensity in the mask image being filled.
The command line usage is given as follows:
Usage: plastimatch fill [options]
Options:
--input <arg> input directory or filename; can be an image
or dicom directory
--mask <arg> input filename for mask image
--mask-value <arg> value to set for pixels within mask (for
"fill"), or outside of mask (for "mask"
--output <arg> output filename (for image file) or directory
(for dicom)
--output-format <arg> arg should be "dicom" for dicom output
--output-type <arg> type of output image, one of {uchar, short,
float, ...}
Suppose we have a file prostate.nrrd which is zero outside of the prostate, and non-zero inside of the prostate. We can fill the prostate with an intensity of 1000, while leaving non-prostate areas with their original intensity, using the following command.
plastimatch fill \ --input infile.nrrd \ --output outfile.nrrd \ --mask-value 1000 \ --mask prostate.nrrd
The header command is used to display simple properties about the volume, such as the image data type and image geometry.
The command line usage is given as follows:
Usage: plastimatch header [options] input_file [input_file ...]
Options:
-h, --help display this help message
--version display the program version
We can display the geometry of any supported file type, such as mha, nrrd, or dicom. We can run the command as follows:
$ plastimatch header input.mha Type = float Planes = 1 Origin = -180 -180 -167.75 Size = 512 512 120 Spacing = 0.7031 0.7031 2.5 Direction = 1 0 0 0 1 0 0 0 1
From the header information, we see that the image has 120 slices, and each slice is 512 x 512 pixels. The slice spacing is 2.5 mm, and the in-plane pixel spacing is 0.7031 mm.
The mask command is used to fill an image region with a constant intensity. The region filled is defined by a mask file, with voxels with zero intensity in the mask image being filled. Thus, it is the inverse of the fill command.
The command line usage is given as follows:
Usage: plastimatch mask [options]
Options:
--input <arg> input directory or filename; can be an image
or dicom directory
--mask <arg> input filename for mask image
--mask-value <arg> value to set for pixels within mask (for
"fill"), or outside of mask (for "mask"
--output <arg> output filename (for image file) or directory
(for dicom)
--output-format <arg> arg should be "dicom" for dicom output
--output-type <arg> type of output image, one of {uchar, short,
float, ...}
Suppose we have a file called patient.nrrd, which is zero outside of the patient, and non-zero inside the patient. If we want to fill in the area outside of the patient with value -1000, we use the following command.
plastimatch mask \ --input infile.nrrd \ --output outfile.nrrd \ --negate-mask \ --mask-value -1000 \ --mask patient.nrrd
The plastimatch probe command is used to examine the image intensity or vector field displacement at one or more positions within a volume. The probe positions can be specified in world coordinates (in mm), using the --location option, or as image indices using the --index option. The locations or indices are linearly interpolated if they lie between voxels.
The command line usage is given as follows:
Usage: plastimatch probe [options] file
Options:
-i, --index <arg> List of voxel indices, such as "i j k;i j k;..."
-l, --location <arg> List of spatial locations, such as
"i j k;i j k;..."
The command will output one line for each probe requested. Each output line includes the following fields.:
PROBE# The probe number, starting with zero
INDEX The (fractional) position of the probe as a voxel index
LOC The position of the probe in world coordinates
VALUE The intensity (for volumes) or displacement
(for vector fields)
We use the index option to see an image intensity at coordinate (2,3,4), and the location option to see image intensities at two different locations:
plastimatch probe \ --index "2 3 4" \ --location "0 0 0; 0.5 0.5 0.5" \ infile.nrrd
The output will include three probe results. Each probe shows the probe index, voxel index, voxel location, and intensity.
0: 2.00, 3.00, 4.00; -22.37, -21.05, -19.74; -998.725891 1: 19.00, 19.00, 19.00; 0.00, 0.00, 0.00; -0.000197 2: 19.38, 19.38, 19.38; 0.50, 0.50, 0.50; -9.793450
The plastimatch register command is used to peform linear or deformable registration of two images. The command line usage is given as follows:
Usage: plastimatch register command_file
The command file is an ordinary text file, which contains a single global section and one or more stages sections. The global section begins with a line containing only the string "[GLOBAL]", and each stage begins with a line containing the string "[STAGE]".
The global section is used to set input files, output files, and global parameters, while the each stage section defines a sequential stage of processing. For a complete description of the command file syntax, please refer to the registration_command_file_reference.
If you want to register image_2.mha to match image_1.mha using B-spline registration, create a command file like this:
# command_file.txt [GLOBAL] fixed=image_1.mha moving=image_2.mha img_out=warped_2.mha xform_out=bspline_coefficients.txt [STAGE] xform=bspline impl=plastimatch threading=openmp max_its=30 regularization_lambda=0.005 grid_spac=100 100 100 res=4 4 2
Then, run the registration like this:
plastimatch register command_file.txt
The above example only performs a single registration stage. If you want to do multi-stage registration, use multiple [STAGE] sections. Like this:
# command_file.txt [GLOBAL] fixed=image_1.mha moving=image_2.mha img_out=warped_2.mha xform_out=bspline_coefficients.txt [STAGE] xform=bspline impl=plastimatch threading=openmp max_its=30 regularization_lambda=0.005 grid_spac=100 100 100 res=4 4 2 [STAGE] max_its=30 grid_spac=80 80 80 res=2 2 1 [STAGE] max_its=30 grid_spac=60 60 60 res=1 1 1
For more examples, please refer to the image_registration_guidebook.
The resample command can be used to change the geometry of an image.
The command line usage is given as follows:
Usage: plastimatch resample [options]
Required: --input=file
--output=file
Optional: --subsample="x y z"
--fixed=file
--origin="x y z"
--spacing="x y z"
--size="x y z"
--output_type={uchar,short,ushort,float,vf}
--interpolation={nn, linear}
--default_val=val
We can use the --subsample option to bin an integer number of voxels to a single voxel. So for example, if we want to bin a cube of size 3x3x1 voxels to a single voxel, we would do the following.
plastimatch resample \ --input infile.nrrd \ --output outfile.nrrd \ --subsample "3 3 1"
The scale command scales an image or vector field by multiplying each voxel by a constant value.
The command line usage is given as follows:
Usage: plastimatch scale [options] input_file
Options:
--output <arg> filename for output image or vector field
--weight <arg> scale the input image or vector field by this
value (float)
This command creates an output file with image intensity (or voxel length) twice as large as the input values:
plastimatch scale --output output.mha --weight 2.0 input.mha
The segment command does simple threshold-based semgentation. The command line usage is given as follows:
Usage: plastimatch segment [options]
Options:
-h, --help Display this help message
--input <arg> Input image filename (required)
--lower-threshold <arg> Lower threshold (include voxels
above this value)
--output-dicom <arg> Output dicom directory (for RTSTRUCT)
--output-img <arg> Output image filename
--upper-threshold <arg> Upper threshold (include voxels
below this value)
Suppose we have a CT image of a water tank, and we wish to create an image which has ones where there is water, and zeros where there is air. Then we could do this:
plastimatch segment \ --input water.mha \ --output-img water-label.mha \ --lower-threshold -500
If we wanted instead to create a DICOM-RT structure set, we should specify a DICOM image as the input. This will allow plastimatch to create the DICOM-RT with the correct patient name, patient id, and UIDs. The output file will be called "ss.dcm".
plastimatch segment \ --input water_dicom \ --output-dicom water_dicom \ --lower-threshold -500
The plastimatch stats command displays a few basic statistics about the image onto the screen.
The command line usage is given as follows:
Usage: plastimatch stats file [file ...]
The input files can be either 2D projection images, 3D volumes, or 3D vector fields.
The following command displays statistics for the 3D volume synth_1.mha.
$ plastimatch stats synth_1.mha MIN -999.915161 AVE -878.686035 MAX 0.000000 NUM 54872
The reported statistics are interpreted as follows:
MIN Minimum intensity in image AVE Average intensity in image MAX Maximum intensity in image NUM Number of voxels in image
The following command displays statistics for the 3D vector field vf.mha:
$ plastimatch stats vf.mha Min: 0.000 -0.119 -0.119 Mean: 13.200 0.593 0.593 Max: 21.250 1.488 1.488 Mean abs: 13.200 0.594 0.594 Energy: MINDIL -6.7975 MAXDIL 0.16602 MAXSTRAIN 41.576 TOTSTRAIN 70849.7 Min dilation at: (29 19 19) Jacobian: MINJAC -6.32835 MAXJAC 1.15443 MINABSJAC 0.360538 Min abs jacobian at: (28 36 36) Second derivatives: MINSECDER 0 MAXSECDER 388.82 TOTSECDER 669219 INTSECDER 1.524e+06 Max second derivative: (29 36 36)
The rows corresponding to "Min, Mean, Max, and Mean abs" each have three numbers, which correspond to the x, y, and z coordinates. Therefore, they compute these statistics for each vector direction separately.
The remaining statistics are described as follows:
MINDIL Minimum dilation MAXDIL Maximum dilation MAXSTRAIN Maximum strain TOTSTRAIN Total strain MINJAC Minimum Jacobian MAXJAC Maximum Jacobian MINABSJAC Minimum absolute Jacobian MINSECDER Minimum second derivative MAXSECDER Maximum second derivative TOTSECDER Total second derivative INTSECDER Integral second derivative
The synth command creates a synthetic image. The following kinds of images can be created, by specifying the appropriate --pattern option. Each of these patterns come with a synthetic structure set and synthetic dose which can be used for testing.
donut -- a donut shaped structure
gauss -- a Gaussian blur
grid -- a 3D grid
lung -- a synthetic lung with a tumor
rect -- a uniform rectangle within a uniform background
sphere -- a uniform sphere within a uniform background
xramp -- an image that linearly varies intensities in the x direction
yramp -- an image that linearly varies intensities in the y direction
zramp -- an image that linearly varies intensities in the z direction
The command line usage is given as follows:
Usage: plastimatch synth [options]
Options:
--background <arg> intensity of background region
--dim <arg> size of output image in voxels "x [y z]"
--direction-cosines <arg>
oriention of x, y, and z axes; Specify
either preset value, {identity,
rotated-{1,2,3},sheared}, or 9 digit
matrix string "a b c d e f g h i"
--donut-center <arg> location of donut center in mm "x [y z]"
--donut-radius <arg> size of donut in mm "x [y z]"
--donut-rings <arg> number of donut rings (2 rings for
traditional donut)
--dose-center <arg> location of dose center in mm "x y z"
--dose-size <arg> dimensions of dose aperture in mm "x [y z]",
or locations of rectangle corners in
mm "x1 x2 y1 y2 z1 z2"
--fixed <arg> fixed image (match output size to this
image)
--foreground <arg> intensity of foreground region
--gauss-center <arg> location of Gaussian center in mm "x [y z]"
--gauss-std <arg> width of Gaussian in mm "x [y z]"
--grid-pattern <arg> grid pattern spacing in voxels "x [y z]"
--lung-tumor-pos <arg> position of tumor in mm "z" or "x y z"
--origin <arg> location of first image voxel in mm "x y z"
--output <arg> output filename
--output-dicom <arg> output dicom directory
--output-dose-img <arg> filename for output dose image
--output-ss-img <arg> filename for output structure set image
--output-ss-list <arg> filename for output file containing
structure names
--output-type <arg> data type for output image: {uchar, short,
ushort, ulong, float}, default is float
--pattern <arg> synthetic pattern to create: {donut, dose,
enclosed_rect, gauss, grid, lung, osd,
rect, sphere, xramp, yramp, zramp},
default is gauss
--penumbra <arg> width of dose penumbra in mm
--rect-size <arg> width of rectangle in mm "x [y z]", or
locations of rectangle corners in mm
"x1 x2 y1 y2 z1 z2"
--spacing <arg> voxel spacing in mm "x [y z]"
--sphere-center <arg> location of sphere center in mm "x y z"
--sphere-radius <arg> radius of sphere in mm "x [y z]"
--volume-size <arg> size of output image in mm "x [y z]"
Create a cubic water phantom 30 x 30 x 40 cm with zero position at the center of the water surface:
plastimatch synth \ --pattern rect \ --output water_tank.mha \ --rect-size "-150 150 0 400 -150 150" \ --origin "-245.5 245.5 -49.5 449.5 -149.5 149.5" \ --spacing "1 1 1" \ --dim "500 500 300"
Create lung phantoms with two different tumor positions, and output to dicom:
plastimatch synth \ --pattern lung \ --output-dicom lung_inhale \ --lung-tumor-pos "0 0 10" plastimatch synth \ --pattern lung \ --output-dicom lung_exhale \ --lung-tumor-pos "0 0 -10"
The synth-vf command creates a synthetic vector field. The following kinds of vector fields can be created, by specifying the appropriate option.
gauss -- a gaussian warp
radial -- a radial expansion or contraction
translation -- a uniform translation
zero -- a vector field that is zero everywhere
The command line usage is given as follows:
Usage: plastimatch synth-vf [options]
Options:
--dim <arg> size of output image in voxels "x [y z]"
--direction-cosines <arg>
oriention of x, y, and z axes; Specify either
preset value, {identity, rotated-{1,2,3},
sheared}, or 9 digit matrix string "a b c
d e f g h i"
--fixed <arg> An input image used to set the size of the
output
--gauss-center <arg> location of center of gaussian warp "x [y z]"
--gauss-mag <arg> displacment magnitude for gaussian warp in
mm "x [y z]"
--gauss-std <arg> width of gaussian std in mm "x [y z]"
--origin <arg> location of first image voxel in mm "x y z"
--output <arg> output filename
--radial-center <arg> location of center of radial warp "x [y z]"
--radial-mag <arg> displacement magnitude for radial warp in
mm "x [y z]"
--spacing <arg> voxel spacing in mm "x [y z]"
--volume-size <arg> size of output image in mm "x [y z]"
--xf-gauss gaussian warp
--xf-radial radial expansion (or contraction)
--xf-trans <arg> uniform translation in mm "x y z"
--xf-zero Null transform
The thumbnail command generates a two-dimensional thumbnail image of an axial slice of the input volume. The output image is not required to correspond exactly to an integer slice number. The location of the output image within the slice is always centered.
The command line usage is given as follows:
Usage: plastimatch thumbnail [options] input-file Options: --input file --output file --thumbnail-dim size --thumbnail-spacing size --slice-loc location
We create a two-dimensional image with resolution 10 x 10 pixels, at axial location 0, and of size 20 x 20 mm:
plastimatch thumbnail \ --input in.mha --output out.mha \ --thumbnail-dim 10 \ --thumbnail-spacing 2 \ --slice-loc 0
The union command creates a binary volume which is the logical union of two input images. Voxels in the output image have value one if the voxel is non-zero in either input image, or value zero if the voxel is zero in both input images.
The command line usage is given as follows:
Usage: plastimatch union [options] input_1 input_2
Options:
-h, --help display this help message
--output <arg> filename for output image
--version display the program version
The following command creates a volume that is the union of two input images:
plastimatch union \ --output itv.mha \ phase_1.mha phase_2.mha
The warp command is an alias for convert. Please refer to plastimatch convert for the list of command line parameters.
To warp an image using the B-spline coefficients generated by the plastimatch register command (saved in the file bspline.txt), do the following:
plastimatch warp \ --input infile.nrrd \ --output outfile.nrrd \ --xf bspline.txt
In the previous example, the output file geometry was determined by the geometry information in the bspline coefficient file. You can resample to a different geometry using --fixed, or --origin, --dim, and --spacing.
plastimatch warp \ --input infile.nrrd \ --output outfile.nrrd \ --xf bspline.txt \ --fixed reference.nrrd
When warping a structure set image, where the integer bits correspond to structure membership, you need to use nearest neighbor interpolation rather than linear interpolation.
plastimatch warp \ --input structures-in.nrrd \ --output structures-out.nrrd \ --xf bspline.txt \ --interpolation nn
Sometimes, voxels located outside of the geometry of the input image will be warped into the geometry of the output image. By default, these areas are "filled in" with an intensity of zero. You can choose a different value for these areas using the --default-val option.
plastimatch warp \ --input infile.nrrd \ --output outfile.nrrd \ --xf bspline.txt \ --default-val -1000
In addition to images and structures, landmarks exported from 3D Slicer can also be warped.
plastimatch warp \ --input fixed_landmarks.fcsv \ --output-pointset warped_landmarks.fcsv \ --xf bspline.txt
Sometimes, it may be desirable to apply a transform explicitly defined by a vector field instead of using B-spline coefficients. To allow this, the --xf option also accepts vector field volumes. For example, the previous example would become.
plastimatch warp \ --input fixed_landmarks.fcsv \ --output-pointset warped_landmarks.fcsv \ --xf vf.mha
The xf-convert command converts between transform types. A tranform can be either a B-spline transform, or a vector field. There are two different kinds of B-spline transform formats: the plastimatch native format, and the ITK format. In addition to converting the transform type, the xf-convert command can also change the grid-spacing of B-spline transforms.
The command line usage is given as follows:
Usage: plastimatch xf-convert [options]
Options:
--dim <arg> Size of output image in voxels "x [y z]"
--grid-spacing <arg> B-spline grid spacing in mm "x [y z]"
--input <arg> Input xform filename (required)
--nobulk Omit bulk transform for itk_bspline
--origin <arg> Location of first image voxel in mm "x y z"
--output <arg> Output xform filename (required)
--output-type <arg> Type of xform to create (required), choose from
{bspline, itk_bspline, vf}
--spacing <arg> Voxel spacing in mm "x [y z]"
We want to convert a B-spline transform into a vector field. If the B-spline transform is in native-format, the vector field geometry is defined by the values found in the transform header.:
plastimatch xf-convert \ --input bspline.txt \ --output vf.mha \ --output-type vf
Likewise, if we want to convert a vector field into a set of B-spline coefficients with a control-point spacing of 30 mm in each direction.
plastimatch xf-convert \ --input vf.mha \ --output bspline.txt \ --output-type bspline \ --grid-spacing 30
Plastimatch is a collaborative project. For additional documentation, please visit http://plastimatch.org. For questions, comments, and bug reports, please visit http://groups.google.com/group/plastimatch.
Plastimatch development team (C) 2010-2013. You are free to use, modify, and distribute plastimatch according to a BSD-style license. Please see LICENSE.TXT for details.