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diff --git a/sys/imfort/doc/impixf.hlp b/sys/imfort/doc/impixf.hlp new file mode 100644 index 00000000..b5ccb335 --- /dev/null +++ b/sys/imfort/doc/impixf.hlp @@ -0,0 +1,53 @@ +.help impixf Sep86 imfort +.ih +NAME +impixf -- get the physical attributes of the pixel file +.ih +SYNOPSIS +.nf +subroutine impixf (im, pixfd, pixfil, pixoff, szline, ier) + +integer im #I image descriptor of open image +integer pixfd #O BFIO file descriptor of pixel file +character*(*) pixfil #O host filename of pixel file +integer pixoff #O 1-indexed "char" offset of pixels +integer szline #O "chars" per physical image line +integer ier #O status return +.fi +.ih +DESCRIPTION +The \fIimpixf\fR procedure is used to obtain information describing the +physical layout of the pixel segment of an image in a binary disk file. +The pixel array of an image accessible via the IMFORT interface is stored +externally in the host file \fIpixfil\fR in line storage mode (as in a +Fortran array). Each line of the image is stored as a contiguous array of +pixels accessible via a BFIO \fIbfread\fR or \fIbfwrit\fR request at the +offset of the first pixel in the line. The first image line (beginning at +pixel [1,1,1,...]) is stored at the file offset given by \fIpixoff\fR. +Each line consumes exactly \fIszline\fR chars of storage; lines may be +blocked to fill an integral number of disk blocks for more efficient access, +hence \fIszline\fR is not directly computable from \fIaxlen(1)\fR. + +Since \fIimpixf\fR is called on an open image, the pixel file will already +have been opened for random access buffered binary file i/o via the BFIO +interface. The BFIO file descriptor of the open pixel file is returned in +\fIpixfd\fR. This may be used in conjunction with BFIO to directly access +the pixel data. If the pixel data is to be accessed via explicit calls +to lower level host system facilities, the image should first be closed +with \fIimclos\fR to avoid possible problems with having the same file +opened multiple times. +.ih +RETURN VALUE +A zero status is returned for any image which has a valid image descriptor. + +IE_MAGIC: illegal imfort image descriptor +.ih +NOTES +Programs which make use of the information provided by \fIimpixf\fR have +explicit knowledge of the physical image storage format and hence may not +work with future versions of the IMFORT interface supporting new physical +image storage formats. +.ih +SEE ALSO +imgsiz, imgs, imps, imgl, impl, bfread, bfwrit +.endhelp |