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Expires: 21 Jan 2004 00:00:00 GMT
Subject: Medical Image Format FAQ, Part 5/8
From: [e-mail] (David A. Clunie)
Followup-To: alt.image.medical
Reply-To: [e-mail] (David A. Clunie)
Approved: [e-mail]
Summary: This posting contains answers to the most Frequently Asked
         Question on alt.image.medical - how do I convert from image
         format X from vendor Y to something I can use ? In addition
         it contains information about various standard formats.
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Date: Sun, 21 Dec 2003 14:16:46 GMT
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Archive-name: medical-image-faq/part5
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Last-modified: Sun Dec 21 09:16:46 EST 2003
Version: 4.26

    3.4 Proprietary Workstations

    3.4.1 ISG Workstations

          3.4.1.1 Gyroview


              The Philips Gyroview workstation is a high-resolution
              graphical workstation for MR images from Gyroscan
              scanners, that can also handle CT images and other
              modalities, and has an optional package for three
              dimensional processing of images.  It is based on a Sun
              SPARC system with proprietary graphics hardware.  The
              software is actually written by ISG in Canada.  The image
              format is an ACR/NEMA based format with various private
              tags defined, and a proprietary scheme of image
              compression that has me stumped.  I am told by some that
              there is no means of telling the Gyroview not to compress
              the images.


             I use compress in the sense that includes packing four 12
             bit words into three 16 bit big-endian words, which appears
             to be part of the scheme in use.  Unfortunately, some form
             of perimeter encoding is also in use, and I just can't
             figure it out :( Some people have had more luck using "the
             export utility of the Gyroview" to produce just 12 bit
             packed images without the perimeter encoding.  I don't know
             whether this is a standard feature of the workstation or
             not.  Others have suggested looking in the
             "/isg/3dmr/DataRoot/tscript/" directory for hints.


              Despite prolonged exchanges of email it seems that the
              formal decision is not to release the format.  Customers
              may contact ISG at [e-mail](Harry Visser) to bitch
              about this and then give up and ask for information on how
              to obtain a software package called the External
              Developers Tool which contains a tool called xdimage which
              can only be used on ISG's proprietary hardware.  This is
              free to customers.  It does however only export to (and
              import from) a flat file format and ascii description, not
              an ACR/NEMA style file with uncompressed pixel data :(.


              I would still prefer to know the format, as people keep
              asking (these machines were pretty popular I gather), and
              if anyone has any hints about the data format, I would
              appreciate them.  Here follows part of a reply to one of
              these people when I made an unsuccesful attempt to figure
              this out:


              Firstly, I presume this file is generated by a Philips
              Gyroview workstation judging by ...


(0008,0070) LO Manufacturer VR=<LO> VL=<8> <GYROVIEW>


              The file says it is an MRI image ...


(0008,0060) CS Modality VR=<CS> VL=<2> <MR>


              and yet it is missing many of the mri attributes normally
              present.  Also it includes some CT specific attributes,
              notably ...


(0018,1120) DS GantryDetectorTilt VR=<DS> VL=<2> < 0>


              which is pretty weird.  I presume that this format is
              generated by something purely for the purposes of 3D
              reconstruction and only the attributes needed for that
              have been preserved.


              The image appears to be 512*512 ...


(0028,0010) US Rows VR=<US> VL=<2> [200] (0028,0011) US Columns VR=<US> VL=<2>
[200]


              As far as the compression format is concerned ...


(0028,0060) CS CompressionCode VR=<CS> VL=<2> < 2>


              is not in itself a valid ACR/NEMA value, and hence some
              proprietary variation is in use.  The most important clue
              is ...


(0028,0040) CS ImageFormat VR=<CS> VL=<4> <CIRC>


              which is also not valid ACR/NEMA (only RECT is permitted).
              From this I conclude that some sort of 'circular'
              perimeter encoding scheme is in use that only sends the
              meaningful central pixels in each row and leaves out the
              background.  This is substantiated by the fact that the
              image pixel data seems to be preceded by a table of 257
              long words in ascending order, each value separated by
              relatively low values (80-100 or so).  I suspect that
              these are pointers into the data to the start of each
              row...


% od -x I011_1_001 +1404 | more 0001404 0000 0202 0000 0252 0000 02a2 0000 02f2
0001424 0000 0342 0000 0392 0000 03e2 0000 0432 0001444 0000 0482 0000 04d2 0000
0522 0000 0572 0001464 0000 05c2 0000 0612 0000 0662 0000 06b3 0001504 0000 0705
0000 0757 0000 07ab 0000 0800 0001524 0000 0857 0000 08ae 0000 0905 0000 095e
..

[0000] 000514 -> 000514 [0001] 000594 -> 000080 [0002] 000674 -> 000080 [0003]
000754 -> 000080 [0004] 000834 -> 000080 [0005] 000914 -> 000080

 ...

[0155] 015322 -> 000103 [0156] 015425 -> 000103 [0157] 015527 -> 000102 [0158]
015629 -> 000102

 ...

[0254] 024484 -> 000080 [0255] 024564 -> 000080 [0256] 024564 -> 000000


              The first of these values seems to be a pointer in two
              byte word units past the table, the entries for a series
              of rows, then a final "257th" value that is the same as
              the preceding with a difference of zero, possibly flagging
              the end of the table.


              What confuses me is the fact that there are 256 or so
              entries rather than 512 (number of rows), and that the
              difference values are relatively small for 512 columns.
              Perhaps each entry applies to two successive rows though
              this seems rather peculiar.


              Furthermore, if it is true that the units are two byte
              words, then the last pointer value is much lower than the
              number of remaining bytes in the image pixel data
              attribute, so what are all the other bytes for ?


              The other thing that is going to make extraction difficult
              is the fact that the data are supposed to be 12 bits
              packed into 16 bit words ...


(0028,0100) US BitsAllocated VR=<US> VL=<2> [c] (0028,0101) US BitsStored
VR=<US> VL=<2> [c] (0028,0102) US HighBit VR=<US> VL=<2> [b]


              Hence 3 two byte words are used to store 4 12 bit pixels.
              It may not be easy to figure out in what order this
              packing is performed.  The ACR/NEMA standard has an
              example of its intent in this case, but the byte order was
              never specified for this standard, which had a 16 bit
              hardware data path and was not originally intended for
              offline data storage in bytes, so there are a number of
              possible permutations to deal with :(


              Finally I don't know what to make of the "private" tags
              ...


Unrecognized (0029,0010) VR=<LT> VL=<a> <ISG shadow> Unrecognized (0029,1070)
VR=<LT> VL=<6> < 49128> Unrecognized (0029,1080) VR=<LT> VL=<6> <123432>
Unrecognized (0029,1090) VR=<LT> VL=<2> < 0>


              which presumably have some significance or they wouldn't
              be there !

    3.4.1 GE Workstations

          3.4.2.1 GE Advantage Windows


              The GE Advantage Windows workstation uses the same header
              layout as the Genesis CT and MR systems.  One very
              important proviso though is that the same C header file to
              describe the layout was compiled on the sparc (sun4)
              rather than Genesis (sun3) architecture, and hence, unlike
              the Genesis files, 32 bit integers (include dates and
              times) and 32 bit floats are aligned on 4 byte boundaries
              and 64 bit floats are aligned on 8 bit boundaries.  In
              other words the sequence of fields is the same but the
              offsets are different.  Very annoying.  For details see
              the GE MR Signa 5.x - Genesis description.  For details of
              the sun data types, see Sun.


              The order of the headers is the same as on the archives
              (DAT, WORM or OD), ie.  not the same as the ximg layout.
              Furthermore, the lengths are slightly different from
              Genesis, due to the word alignement business, and also
              different for CT as opposed to MR (different length of the
              image header), so finding the file header (pixel data
              header) can be a bit of a chore.  The offsets from the
              start of the file for each are as follows:


              For CT:

                0 Suite header
              116 Exam header
             1156 Series header 2184 Image header 3240 File (Pixel
             Data) header

              For MR:

                0 Suite header
              116 Exam header
             1156 Series header 2184 Image header 3228 File (Pixel
             Data) header



              Identifying the files is a nuisance because the "IMGF"
              string doesn't appear until offset 3240 dec for the CT and
              offset 3228 dec for the MR, unlike the Genesis ximg form.


              Also, even though the headers are in the "archive" order,
              the 4 byte pixel data length field that is prepended to
              the image pixel data itself in the archives, is NOT
              present on Advantage Windows, just as it is absent from
              Genesis ximg files.  In other words you do not have to add
              4 to the file header length field to find the start of the
              pixel data.  Obviously you do have to add the offset of
              the file header itself though !  Don't forget to add this
              to the offset of the unpack tables also.  The pixel data
              itself is compressed the same way as Genesis.


              It is recommended that you use the readily available
              Genesis documentation if trying to extract information
              from the headers, or use the "ximg -h" command on a
              Genesis system to generate a C header.  For the truly
              masochistic, or desperately impatient, here is a summary
              of the some of the fields for Advantage Windows as were
              described for Genesis CT and MR, with the corrections for
              word alignment applied:


    exam header:

        0 - char[4] - suite ID 8 - u_short - exam number 88 - char[13] -
        patient ID 101 - char[25] - patient name 126 - short - patient
        age 130 - short - patient sex 309 - char[3] - exam type - "MR"
        or "CT"

    series header:

        10 - short - series number 84 - char[3] - anatomical reference
        92 - char[25] - scan protocol name

    image header - common to CT and MR:

        12 - short - image number 28 - float - slice thickness mm 32 -
        short - matrix size - X 34 - short - matrix size - Y 36 - float
        - display field of view - X (mm) 40 - float - display field of
        view - Y (mm) 44 - float - image dimension - X 48 - float -
        image dimension - Y 52 - float - pixel size - X 56 - float -
        pixel size - Y 60 - char[14] - pixel data ID 74 - char[17] - iv
        contrast agent 91 - char[17] - oral contrast agent

        132 - float - image location 136 - float - image centre R mm
        (ie.  X +ve to right) 140 - float - image centre A mm (ie.  Y
        +ve to anterior) 144 - float - image centre S mm (ie.  Z +ve to
        superior) 160 - float - image TLHC R mm (ie.  X +ve to right)
        164 - float - image TLHC A mm (ie.  Y +ve to anterior) 168 -
        float - image TLHC S mm (ie.  Z +ve to superior) 172 - float -
        image TRHC R mm (ie.  X +ve to right) 176 - float - image TRHC A
        mm (ie.  Y +ve to anterior) 180 - float - image TRHC S mm (ie.
        Z +ve to superior) 184 - float - image BRHC R mm (ie.  X +ve to
        right) 188 - float - image BRHC A mm (ie.  Y +ve to anterior)
        192 - float - image BRHC S mm (ie.  Z +ve to superior)

    image header - for MR (1044 bytes long):

        200 - int - repetition time(usec) 204 - int - inversion
        time(usec) 208 - int - echo time(usec) 216 - short - number of
        echoes 218 - short - echo number 224 - float - NEX 320 -
        char[33] - pulse sequence name 376 - char[17] - coil name 660 -
        short - ETL for FSE

    image header - for CT (1056 bytes long):

        200 - float - table start Location 204 - float - table end
        Location 208 - float - table speed (mm/sec) 212 - float - table
        height 232 - float - gantry tilt (degrees)

    3.5 Other Proprietary Formats

    3.5.1 Analyze From Mayo

          This very popular software package is produced by the Biomedical
          Imaging Resource group at the Mayo Clinic/Foundation.  I have
          always thought they should give it away but they don't, it is
          moderately expensive, though less so than some other alternatives.
          If you want to test or buy it try contacting Denny Hanson
          [e-mail] who is extremely helpful.  See also the web site at
          ANALYZE from Mayo.


          Anyway, importing images into Analyze is a drag and you have to
          convert your files to their format, but it isn't very difficult.
          I hear that some other programs also use their format but haven't
          encountered them myself.  Anyway, the package is sufficiently
          commonly used that it seems appropriate to include the format
          here.


          This information is included verbatim from what was sent to me by
          Ellis Workman [e-mail] and if you have problems I am sure he
          will be able to help.  I haven't tested it because I can't afford
          to buy a copy myself :( That's a hint, Denny.


ANALYZE IMAGE FILE FORMAT

ANALYZE image file sets consist of at least 2 files:
    - an image file - a header file - a color lookup file * optional

For the Analyze image file set "foo" there are two files:
    foo.img & foo.hdr (optionally foo.lkup)

The ANALYZE programs refer to this file set as a single entity.

       The Image File (foo.img)

The format of the image file is very simple; containging usually uncompressed
voxel data for the images in one of the several possible voxel formats:
    - 1 bit packed binary (slices begin on byte boundaries) - 8 bit
    (unsigned char) gray scale unless .lkup file present - 16 bit signed
    short - 32 bit signed integers or float - 24 bit RGB, 8 bits per channel

The header file is a 'C' structure which describes the dimensions and properties
of the voxel data.  This structure follows:


/*
 * * (c) Copyright, 1986-1995 * Biomedical Imaging Resource * Mayo Foundation *
 * dbh.h * * * database sub-definitions */

struct header_key /* header_key */
    { /* off + size*/
    int sizeof_hdr; /* 0 + 4 */ char data_type[10]; /* 4 + 10 */ char
    db_name[18]; /* 14 + 18 */ int extents; /* 32 + 4 */ short int
    session_error; /* 36 + 2 */ char regular; /* 38 + 1 */ char hkey_un0; /*
    39 + 1 */
    }; /* total=40 */

struct image_dimension /* image_dimension */
    { /* off + size*/
    short int dim[8]; /* 0 + 16 */ char vox_units[4]; /* 16 + 4 */ char
    cal_units[8]; /* 20 + 4 */ short int unused1; /* 24 + 2 */ short int
    datatype; /* 30 + 2 */ short int bitpix; /* 32 + 2 */ short int dim_un0;
    /* 34 + 2 */ float pixdim[8]; /* 36 + 32 */
            /*
                pixdim[] specifies the voxel dimensions:
                pixdim[1] - voxel width pixdim[2] - voxel height
                pixdim[3] - interslice distance
                    ..etc
            */
    float vox_offset; /* 68 + 4 */ float roi_scale; /* 72 + 4 */ float
    funused1; /* 76 + 4 */ float funused2; /* 80 + 4 */ float cal_max; /* 84
    + 4 */ float cal_min; /* 88 + 4 */ int compressed; /* 92 + 4 */ int
    verified; /* 96 + 4 */ int glmax, glmin; /* 100 + 8 */
    }; /* total=108 */

struct data_history /* data_history */
    { /* off + size*/
    char descrip[80]; /* 0 + 80 */ char aux_file[24]; /* 80 + 24 */ char
    orient; /* 104 + 1 */ char originator[10]; /* 105 + 10 */ char
    generated[10]; /* 115 + 10 */ char scannum[10]; /* 125 + 10 */ char
    patient_id[10]; /* 135 + 10 */ char exp_date[10]; /* 145 + 10 */ char
    exp_time[10]; /* 155 + 10 */ char hist_un0[3]; /* 165 + 3 */ int views;
    /* 168 + 4 */ int vols_added; /* 172 + 4 */ int start_field; /* 176 + 4
    */ int field_skip; /* 180 + 4 */ int omax,omin; /* 184 + 8 */ int
    smax,smin; /* 192 + 8 */
    }; /* total=200 */

struct dsr /* dsr */
    { /* off + size*/
    struct header_key hk; /* 0 + 40 */ struct image_dimension dime; /* 40 +
    108 */ struct data_history hist; /* 148 + 200 */
    }; /* total=348 */


Comments:
    struct header_key
        int sizeof_header /* must indicate size of header file */ int
        extants; /* should be 16384 */ char regular; /* 'r' */


    struct image_dimension struct decribes the organization and side of
    images.  These elements enable IO routines to reference images by volume
    and slice number.

        short int dim[] /* array of image dimensions */
            dim[0] /* number of dimensions; usually 4 */ dim[1] /*
            image width */ dim[2] /* image height */ dim[3] /*
            volume depth */ dim[4] /* volumes in file */

        char vox_units[4] /* labels voxerl spatial unit */ char
        cal_units[4] /* labels voxel calibration unit */ short int
        datatype /* Acceptable values are */

#define DT_NONE 0 #define DT_UNKNOWN 0 #define DT_BINARY 1 #define
DT_UNSIGNED_CHAR 2 #define DT_SIGNED_SHORT 4 #define DT_SIGNED_INT 8 #define
DT_FLOAT 16 #define DT_COMPLEX 32 #define DT_DOUBLE 64 #define DT_RGB 128
#define DT_ALL 255

        short int bitpix /* bits per pixel */ float pixdim[] /* parallel
        array to dim giving voxel dimensions
                   in each dimension */
             pixdim[1] /* voxel width */ pixdim[2] /* voxel height
             */ pixdim[3] /* voxel depth or slice thickness */

        float vox_offset; /* byte offset in the .img file at which
                     voxels start.  If value is negative
                     specifies that the absolute value is
                     applied for every image in the file.  */

        float calibrated Max & Min /* specify range of calibration
        values */ int glmax, glmin /* the max and min values for entire
        data set */


The data_history substructure is not required, but the 'orient' element is used
to indicate individual slice orientation and determines whether the ANALYZE
'Movie' program will attempt to flip the images before displaying a movie
sequence.
    orient:
            0 - transverse unflipped 1 - coronal unflipped 2 -
            sagittal unflipped 3 - transverse flipped 4 - coronal
            flipped 5 - sagittal flipped



The following 'C' program creates an Analyze .hdr file.


/*
 * (c) Copyright, 1986-1994 * Biomedical Imaging Resource * Mayo Foundation * *
 */

#include #include "dbh.h"

main(argc,argv) /* file x y z t datatype max min */ int argc; char **argv; {
    int i; struct dsr hdr; FILE *fp; static char DataTypes[9][12] = {"UNKNOWN",
    "BINARY", "CHAR", "SHORT", "INT",
                    "FLOAT", "COMPLEX", "DOUBLE", "RGB"};


    static int DataTypeSizes[9] = {0,1,8,16,32,32,64,64,24};

    if(argc != 9) {
    usage(); exit(0);
    } memset(&hdr,0, sizeof(struct dsr)); for(i=0;i<8;i++)
    hdr.dime.pixdim[i]=0.0;

    hdr.dime.vox_offset = 0.0; hdr.dime.roi_scale = 1.0; hdr.dime.funused1 =
    0.0; hdr.dime.funused2 = 0.0; hdr.dime.cal_max = 0.0; hdr.dime.cal_min =
    0.0;


    hdr.dime.datatype = -1;

    for(i=1;i<=8;i++)
    if(!strcmp(argv[6],DataTypes[i])) {
        hdr.dime.datatype = (1<<(i-1)); hdr.dime.bitpix =
        DataTypeSizes[i]; break;
    }

    if(hdr.dime.datatype <= 0) {
    printf(" is an unacceptable datatype \n\n", argv[6]); usage(); exit(0);
    }

    if((fp=fopen(argv[1],"w"))==0) {
    printf("unable to create: %s\n",argv[1]); exit(0);
    }

    hdr.dime.dim[0] = 4; /* all Analyze images are taken as 4 dimensional */
    hdr.hk.regular = 'r'; hdr.hk.sizeof_hdr = sizeof(struct dsr);

    hdr.dime.dim[1] = atoi(argv[2]); /* slice width in pixels */ hdr.dime.dim[2]
    = atoi(argv[3]); /* slice height in pixels */ hdr.dime.dim[3] =
    atoi(argv[4]); /* volume depth in slices */ hdr.dime.dim[4] = atoi(argv[5]);
    /* number of volumes per file */

    hdr.dime.glmax = atoi(argv[7]); /* maximum voxel value */ hdr.dime.glmin =
    atoi(argv[8]); /* minimum voxel value */

/* Set the voxel dimension fields:
       A value of 0.0 for these fields implies that the value is unknown.
     Change these values to what is appropriate for your data or pass
     additional command line arguments */

    hdr.dime.pixdim[1] = 0.0; /* voxel x dimension */ hdr.dime.pixdim[2] = 0.0;
    /* voxel y dimension */ hdr.dime.pixdim[3] = 0.0; /* pixel z dimension,
    slice thickness */

/* Assume zero offset in .img file, byte at which pixel
       data starts in the image file */

    hdr.dime.vox_offset = 0.0;

/* Planar Orientation; */ /* Movie flag OFF: 0 = transverse, 1 = coronal, 2 =
sagittal
     Movie flag ON: 3 = transverse, 4 = coronal, 5 = sagittal */

    hdr.hist.orient = 0;

/* up to 3 characters for the voxels units label; i.e.
    mm., um., cm.  */

    strcpy(hdr.dime.vox_units," ");

/* up to 7 characters for the calibration units label; i.e.  HU */

    strcpy(hdr.dime.cal_units," ");

/* Calibration maximum and minimum values;
       values of 0.0 for both fields imply that no calibration max and min
       values are used */

    hdr.dime.cal_max = 0.0; hdr.dime.cal_min = 0.0;

    fwrite(&hdr,sizeof(struct dsr),1,fp); fclose(fp);
}

usage() {
   printf("usage: make_hdr name.hdr x y z t datatype max min \n\n"); printf("
   name.hdr = the name of the header file\n"); printf(" x = width, y = height, z
   = depth, t = number of volumes\n"); printf(" acceptable datatype values are:
   BINARY, CHAR, SHORT,\n"); printf(" INT, FLOAT, COMPLEX, DOUBLE, and RGB\n");
   printf(" max = maximum voxel value, min = minimum voxel value\n");
}


The following program displays information in an Analyze header file.

#include #include "dbh.h"

void ShowHdr(char *, struct dsr *); void swap_long(unsigned char *); void
swap_short(unsigned char *);

main(argc,argv) int argc; char **argv;
    { struct dsr hdr; int size; double cmax, cmin; FILE *fp;

    if((fp=fopen(argv[1],"r"))==NULL)
    {
    fprintf(stderr,"Can't open:\n", argv[1]); exit(0);
    } fread(&hdr,1,sizeof(struct dsr),fp);

    if(hdr.dime.dim[0] 15)
        swap_hdr(&hdr);

     ShowHdr(argv[1], &hdr);


     }




void ShowHdr(fileName,hdr) struct dsr *hdr; char *fileName; { int i; char
string[128]; printf("Analyze Header Dump of: \n", fileName); /* Header Key */
printf("sizeof_hdr: \n", hdr->hk.sizeof_hdr); printf("data_type: \n",
hdr->hk.data_type); printf("db_name: \n", hdr->hk.db_name); printf("extents:
\n", hdr->hk.extents); printf("session_error: \n", hdr->hk.session_error);
printf("regular: \n", hdr->hk.regular); printf("hkey_un0: \n",
hdr->hk.hkey_un0);

/* Image Dimension */ for(i=0;i<8;i++)
    printf("dim[%d]: \n", i, hdr->dime.dim[i]);

    strncpy(string,hdr->dime.vox_units,4); printf("vox_units: \n", string);

    strncpy(string,hdr->dime.cal_units,8); printf("cal_units: \n", string);
    printf("unused1: \n", hdr->dime.unused1); printf("datatype: \n",
    hdr->dime.datatype); printf("bitpix: \n", hdr->dime.bitpix);

for(i=0;i<8;i++)
    printf("pixdim[%d]: \n",i, hdr->dime.pixdim[i]);

printf("vox_offset: \n", hdr->dime.vox_offset); printf("funused1: \n",
hdr->dime.funused1); printf("funused2: \n", hdr->dime.funused2);
printf("funused3: \n", hdr->dime.funused3); printf("cal_max: \n",
hdr->dime.cal_max); printf("cal_min: \n", hdr->dime.cal_min);
printf("compressed: \n", hdr->dime.compressed); printf("verified: \n",
hdr->dime.verified); printf("glmax: \n", hdr->dime.glmax); printf("glmin: \n",
hdr->dime.glmin);

/* Data History */ strncpy(string,hdr->hist.descrip,80); printf("descrip: \n",
string); strncpy(string,hdr->hist.aux_file,24); printf("aux_file: \n", string);
printf("orient: \n", hdr->hist.orient);

strncpy(string,hdr->hist.originator,10); printf("originator: \n", string);

strncpy(string,hdr->hist.generated,10); printf("generated: \n", string);


strncpy(string,hdr->hist.scannum,10); printf("scannum: \n", string);

strncpy(string,hdr->hist.patient_id,10); printf("patient_id: \n", string);

strncpy(string,hdr->hist.exp_date,10); printf("exp_date: \n", string);

strncpy(string,hdr->hist.exp_time,10); printf("exp_time: \n", string);

strncpy(string,hdr->hist.hist_un0,10); printf("hist_un0: \n", string);

printf("views: \n", hdr->hist.views); printf("vols_added: \n",
hdr->hist.vols_added); printf("start_field: \n", hdr->hist.start_field);
printf("field_skip: \n", hdr->hist.field_skip); printf("omax: \n",
hdr->hist.omax); printf("omin: \n", hdr->hist.omin); printf("smin: \n",
hdr->hist.smax); printf("smin: \n", hdr->hist.smin);

}


swap_hdr(pntr) struct dsr *pntr;
    { swap_long(&pntr->hk.sizeof_hdr) ; swap_long(&pntr->hk.extents) ;
    swap_short(&pntr->hk.session_error) ; swap_short(&pntr->dime.dim[0]) ;
    swap_short(&pntr->dime.dim[1]) ; swap_short(&pntr->dime.dim[2]) ;
    swap_short(&pntr->dime.dim[3]) ; swap_short(&pntr->dime.dim[4]) ;
    swap_short(&pntr->dime.dim[5]) ; swap_short(&pntr->dime.dim[6]) ;
    swap_short(&pntr->dime.dim[7]) ; swap_short(&pntr->dime.unused1) ;
    swap_short(&pntr->dime.datatype) ; swap_short(&pntr->dime.bitpix) ;
    swap_long(&pntr->dime.pixdim[0]) ; swap_long(&pntr->dime.pixdim[1]) ;
    swap_long(&pntr->dime.pixdim[2]) ; swap_long(&pntr->dime.pixdim[3]) ;
    swap_long(&pntr->dime.pixdim[4]) ; swap_long(&pntr->dime.pixdim[5]) ;
    swap_long(&pntr->dime.pixdim[6]) ; swap_long(&pntr->dime.pixdim[7]) ;
    swap_long(&pntr->dime.vox_offset) ; swap_long(&pntr->dime.funused1) ;
    swap_long(&pntr->dime.funused2) ; swap_long(&pntr->dime.cal_max) ;
    swap_long(&pntr->dime.cal_min) ; swap_long(&pntr->dime.compressed) ;
    swap_long(&pntr->dime.verified) ; swap_short(&pntr->dime.dim_un0) ;
    swap_long(&pntr->dime.glmax) ; swap_long(&pntr->dime.glmin) ; }

swap_long(pntr) unsigned char *pntr;
    { unsigned char b0, b1, b2, b3;

    b0 = *pntr; b1 = *(pntr+1); b2 = *(pntr+2); b3 = *(pntr+3);

    *pntr = b3; *(pntr+1) = b2; *(pntr+2) = b1; *(pntr+3) = b0; }

swap_short(pntr) unsigned char *pntr;
    { unsigned char b0, b1;

    b0 = *pntr; b1 = *(pntr+1);

    *pntr = b1; *(pntr+1) = b0; }



The next part is part6 - hosts & compression.