diff options
Diffstat (limited to 'analyzer/pnmpsnr.c')
| -rw-r--r-- | analyzer/pnmpsnr.c | 81 |
1 files changed, 41 insertions, 40 deletions
diff --git a/analyzer/pnmpsnr.c b/analyzer/pnmpsnr.c index a7331d27..1160fff6 100644 --- a/analyzer/pnmpsnr.c +++ b/analyzer/pnmpsnr.c @@ -13,6 +13,7 @@ #include <math.h> #include "pm_c_util.h" +#include "nstring.h" #include "pam.h" #define MAXFILES 16 @@ -47,7 +48,7 @@ validate_input(const struct pam pam1, const struct pam pam2) { pm_error("images do not have the same maxval. This programs works " "only on like maxvals. " "The first image has maxval %u, " - "while the second has %u. Use Pnmdepth to change the " + "while the second has %u. Use Pamdepth to change the " "maxval of one of them.", (unsigned int) pam1.maxval, (unsigned int) pam2.maxval); @@ -66,16 +67,18 @@ validate_input(const struct pam pam1, const struct pam pam2) { static void -psnr_color(tuple const tuple1, tuple const tuple2, +psnr_color(tuple const tuple1, + tuple const tuple2, double * const ySqDiffP, - double * const cbSqDiffP, double * const crSqDiffP) { + double * const cbSqDiffP, + double * const crSqDiffP) { double y1, y2, cb1, cb2, cr1, cr2; pnm_YCbCrtuple(tuple1, &y1, &cb1, &cr1); pnm_YCbCrtuple(tuple2, &y2, &cb2, &cr2); - *ySqDiffP = square(y1 - y2); + *ySqDiffP = square(y1 - y2); *cbSqDiffP = square(cb1 - cb2); *crSqDiffP = square(cr1 - cr2); } @@ -83,45 +86,49 @@ psnr_color(tuple const tuple1, tuple const tuple2, static void -reportPsnr(struct pam const pam1, struct pam const pam2, - double const ySumSqDiff, - double const crSumSqDiff, double const cbSumSqDiff, - const char filespec1[], const char filespec2[]) { +reportPsnr(struct pam const pam, + double const ySumSqDiff, + double const crSumSqDiff, + double const cbSumSqDiff, + char const filespec1[], + char const filespec2[]) { - bool const color = (strcmp(pam1.tuple_type, PAM_PPM_TUPLETYPE) == 0); + bool const color = streq(pam.tuple_type, PAM_PPM_TUPLETYPE); - /* The PSNR is the mean of the sum of squares of the differences, - normalized to the range 0..1 + /* The PSNR is the ratio of the maximum possible mean square difference + to the actual mean square difference. + */ + double const yPsnr = + square(pam.maxval) / (ySumSqDiff / (pam.width * pam.height)); + + /* Note that in the important special case that the images are + identical, the sum square differences are identically 0.0. No + precision error; no rounding error. */ - double const yPsnr = ySumSqDiff - / (pam1.width * pam1.height) - / square(pam1.maxval); if (color) { - double const cbPsnr = cbSumSqDiff - / (pam1.width * pam1.height) - / square(pam1.maxval); - double const crPsnr = crSumSqDiff - / (pam1.width * pam1.height) - / (pam1.maxval * pam2.maxval); + double const cbPsnr = + square(pam.maxval) / (cbSumSqDiff / (pam.width * pam.height)); + double const crPsnr = + square(pam.maxval) / (crSumSqDiff / (pam.width * pam.height)); pm_message("PSNR between %s and %s:", filespec1, filespec2); - if (yPsnr > 1e-9) - pm_message("Y color component: %.2f dB", 10 * log10(1/yPsnr)); + if (ySumSqDiff > 0) + pm_message("Y color component: %.2f dB", 10 * log10(yPsnr)); else pm_message("Y color component does not differ."); - if (cbPsnr > 1e-9) - pm_message("Cb color component: %.2f dB", 10 * log10(1/cbPsnr)); + if (cbSumSqDiff > 0) + pm_message("Cb color component: %.2f dB", 10 * log10(cbPsnr)); else - pm_message("Cb color component does not differ."); - if (crPsnr > 1e-9) - pm_message("Cr color component: %.2f dB", 10 * log10(1/crPsnr)); + pm_message("Cb color component does not differ."); + if (crSumSqDiff > 0) + pm_message("Cr color component: %.2f dB", 10 * log10(crPsnr)); else pm_message("Cr color component does not differ."); } else { - if (yPsnr > 1e-9) + if (ySumSqDiff > 0) pm_message("PSNR between %s and %s: %.2f dB", - filespec1, filespec2, 10 * log10(1/yPsnr)); + filespec1, filespec2, 10 * log10(yPsnr)); else pm_message("Images %s and %s don't differ.", filespec1, filespec2); @@ -166,7 +173,7 @@ main (int argc, char **argv) { tuplerow1 = pnm_allocpamrow(&pam1); tuplerow2 = pnm_allocpamrow(&pam2); - ySumSqDiff = 0.0; + ySumSqDiff = 0.0; cbSumSqDiff = 0.0; crSumSqDiff = 0.0; @@ -181,19 +188,19 @@ main (int argc, char **argv) { double ySqDiff, cbSqDiff, crSqDiff; psnr_color(tuplerow1[col], tuplerow2[col], &ySqDiff, &cbSqDiff, &crSqDiff); - ySumSqDiff += ySqDiff; + ySumSqDiff += ySqDiff; cbSumSqDiff += cbSqDiff; crSumSqDiff += crSqDiff; } else { - unsigned int yDiffSq; - yDiffSq = square(udiff(tuplerow1[col][0], tuplerow2[col][0])); + unsigned int const yDiffSq = + square(udiff(tuplerow1[col][0], tuplerow2[col][0])); ySumSqDiff += yDiffSq; } } } - reportPsnr(pam1, pam2, ySumSqDiff, crSumSqDiff, cbSumSqDiff, + reportPsnr(pam1, ySumSqDiff, crSumSqDiff, cbSumSqDiff, filespec1, filespec2); pnm_freepamrow(tuplerow1); @@ -201,9 +208,3 @@ main (int argc, char **argv) { return 0; } - - - - - - |