diff options
Diffstat (limited to 'converter/pgm/st4topgm.c')
| -rw-r--r-- | converter/pgm/st4topgm.c | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/converter/pgm/st4topgm.c b/converter/pgm/st4topgm.c new file mode 100644 index 00000000..8e4660a3 --- /dev/null +++ b/converter/pgm/st4topgm.c @@ -0,0 +1,260 @@ +/*============================================================================= + st4topgm +=============================================================================== + + Convert an SBIG ST-4 image (not to be confused with the more sophisticated + SBIG format that every other SBIG camera produces) to PGM. + + By Bryan Henderson January 2015. + + Contributed to the public domain by its author. + + This program was intended to substitute for the program of the same name in + the Debian version of Netpbm, by Justin Pryzby <justinpryzby@users.sf.net> + in December 2003. + +=============================================================================*/ +#include <string.h> + +#include "pm_config.h" +#include "pm_c_util.h" +#include "pm.h" +#include "pam.h" + + + +static unsigned int const st4Height = 165; +static unsigned int const st4Width = 192; +static unsigned int const st4Maxval = 255; + + + +static void +validateFileSize(FILE * const ifP) { +/*---------------------------------------------------------------------------- + Abort program if *ifP is not the proper size for an ST-4 SBIG file. + + Don't change file position. +-----------------------------------------------------------------------------*/ + pm_filepos const st4FileSize = (st4Height+1) * st4Width; + + pm_filepos oldFilePos; + pm_filepos endFilePos; + + pm_tell2(ifP, &oldFilePos, sizeof(endFilePos)); + + fseek(ifP, 0, SEEK_END); + + pm_tell2(ifP, &endFilePos, sizeof(endFilePos)); + + pm_seek2(ifP, &oldFilePos, sizeof(oldFilePos)); + + if (endFilePos != st4FileSize) + pm_error("File is the wrong size for an ST-4 SBIG file. " + "It is %u bytes; it should be %u bytes", + (unsigned)endFilePos, (unsigned)st4FileSize); +} + + +static void +writeRaster(FILE * const ifP, + struct pam * const pamP) { + + tuple * tuplerow; + unsigned int row; + + tuplerow = pnm_allocpamrow(pamP); + + for (row = 0; row < st4Height; ++row) { + unsigned int col; + + for (col = 0; col < st4Width; ++col) { + char c; + + pm_readchar(ifP, &c); + + tuplerow[col][0] = (unsigned char)c; + } + pnm_writepamrow(pamP, tuplerow); + } + + pnm_freepamrow(tuplerow); +} + + + +struct St4Footer { +/*---------------------------------------------------------------------------- + The information in an ST-4 SBIG footer. +-----------------------------------------------------------------------------*/ + /* Note that numerical information is in decimal text, because we're lazy. + */ + + char comment[78+1]; + char exposureTime[10+1]; + char focalLength[10+1]; + char apertureArea[10+1]; + char calibrationFactor[10+1]; +}; + + + +static void +stripTrailing(char * const arg) { + + if (strlen(arg) > 0) { + char * p; + for (p = arg + strlen(arg); p > arg && *(p-1) == ' '; --p); + + *p = '\0'; + } +} + + + +static void +stripLeading(char * const arg) { + + const char * p; + + for (p = &arg[0]; *p == ' '; ++p); + + if (p > arg) + memmove(arg, p, strlen(p) + 1); +} + + + +static void +readFooter(FILE * const ifP, + struct St4Footer * const footerP) { +/*---------------------------------------------------------------------------- + Read the footer of the ST-4 image from *ifP, assuming *ifP is positioned + to the footer. + + Return its contents as *footerP. +-----------------------------------------------------------------------------*/ + char buffer[192]; + size_t bytesReadCt; + + /* The footer is laid out as follows. + + off len description + --- --- ----------- + 000 1 Signature: 'v' + 001 78 Freeform comment + 079 10 Exposure time in 1/100s of a second + 089 10 Focal length in inches + 099 10 Aperture area in square inches + 109 10 Calibration factor + 119 73 Reserved + + Note tha the footer is the same length as a raster row. + */ + + bytesReadCt = fread(buffer, 1, sizeof(buffer), ifP); + + if (bytesReadCt != 192) + pm_error("Failed to read footer of image"); + + if (buffer[0] != 'v') + pm_error("Input is not an ST-4 file. We know because the " + "signature byte (first byte of the footer) is not 'v'"); + + buffer[191] = '\0'; + memmove(footerP->comment, &buffer[1], 78); + footerP->comment[78] = '\0'; + stripTrailing(footerP->comment); + + memmove(footerP->exposureTime, &buffer[79], 10); + footerP->exposureTime[10] = '\0'; + stripLeading(footerP->exposureTime); + + memmove(footerP->focalLength, &buffer[89], 10); + footerP->focalLength[10] = '\0'; + stripLeading(footerP->focalLength); + + memmove(footerP->apertureArea, &buffer[99], 10); + footerP->apertureArea[10] = '\0'; + stripLeading(footerP->apertureArea); + + memmove(footerP->calibrationFactor, &buffer[109], 10); + footerP->calibrationFactor[10] = '\0'; + stripLeading(footerP->calibrationFactor); +} + + + +static void +reportFooter(struct St4Footer const footer) { + + pm_message("Comment: %s", footer.comment); + + pm_message("Exposure time (1/100 s): %s", footer.exposureTime); + + pm_message("Focal length (in): %s", footer.focalLength); + + pm_message("Aperture area (sq in): %s", footer.apertureArea); + + pm_message("Calibration factor: %s", footer.calibrationFactor); +} + + + +int +main(int argc, const char **argv) { + + FILE * ifP; + const char * inputFileName; + struct pam outpam; + struct St4Footer footer; + + pm_proginit(&argc, argv); + + if (argc-1 < 1) + inputFileName = "-"; + else { + inputFileName = argv[1]; + if (argc-1 > 1) + pm_error("Too many arguments: %u. " + "The only possible argument is the " + "optional input file name", argc-1); + } + + /* We check the file size to catch the common problem of the input not + being valid ST-4 SBIG input. Unlike most formats, this one does not + have any signature at the head of the file. + + More checks on the validity of the format happens when we process + the image footer. + */ + + ifP = pm_openr_seekable(inputFileName); + + validateFileSize(ifP); + + outpam.size = sizeof(outpam); + outpam.len = PAM_STRUCT_SIZE(maxval); + outpam.file = stdout; + outpam.format = PGM_FORMAT; + outpam.plainformat = false; + outpam.height = st4Height; + outpam.width = st4Width; + outpam.depth = 1; + outpam.maxval = st4Maxval; + + pnm_writepaminit(&outpam); + + writeRaster(ifP, &outpam); + + readFooter(ifP, &footer); + + reportFooter(footer); + + pm_close(ifP); + pm_close(stdout); + + return 0; +} + + |