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git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@1 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 102 insertions, 0 deletions

diff --git a/lib/libpamcolor.c b/lib/libpamcolor.c
new file mode 100644
index 00000000..e11415ca
--- /dev/null
+++ b/lib/libpamcolor.c
@@ -0,0 +1,102 @@
+/*----------------------------------------------------------------------------
+                                  libpamcolor.c
+------------------------------------------------------------------------------
+   These are the library functions, which belong in the libnetpbm library,
+   that deal with colors in the PAM image format.
+-----------------------------------------------------------------------------*/
+
+/* See libpbm.c for the complicated explanation of this 32/64 bit file
+   offset stuff.
+*/
+#define _FILE_OFFSET_BITS 64
+#define _LARGE_FILES  
+
+#include <limits.h>
+
+#include "pm_c_util.h"
+#include "pam.h"
+#include "ppm.h"
+
+
+tuple
+pnm_parsecolor(const char * const colorname,
+               sample       const maxval) {
+
+    tuple retval;
+    pixel color;
+    struct pam pam;
+
+    pam.len = PAM_STRUCT_SIZE(bytes_per_sample);
+    pam.depth = 3;
+    pam.maxval = maxval;
+    pam.bytes_per_sample = pnm_bytespersample(maxval);
+
+    retval = pnm_allocpamtuple(&pam);
+
+    color = ppm_parsecolor(colorname, maxval);
+
+    retval[PAM_RED_PLANE] = PPM_GETR(color);
+    retval[PAM_GRN_PLANE] = PPM_GETG(color);
+    retval[PAM_BLU_PLANE] = PPM_GETB(color);
+
+    return retval;
+}
+
+
+
+double pnm_lumin_factor[3] = {PPM_LUMINR, PPM_LUMING, PPM_LUMINB};
+
+void
+pnm_YCbCrtuple(tuple    const tuple, 
+               double * const YP, 
+               double * const CbP, 
+               double * const CrP) {
+/*----------------------------------------------------------------------------
+   Assuming that the tuple 'tuple' is of tupletype RGB, return the 
+   Y/Cb/Cr representation of the color represented by the tuple.
+-----------------------------------------------------------------------------*/
+    int const red = (int)tuple[PAM_RED_PLANE];
+    int const grn = (int)tuple[PAM_GRN_PLANE];
+    int const blu = (int)tuple[PAM_BLU_PLANE];
+    
+    *YP  = (+ PPM_LUMINR * red + PPM_LUMING * grn + PPM_LUMINB * blu);
+    *CbP = (- 0.16874 * red - 0.33126 * grn + 0.50000 * blu);
+    *CrP = (+ 0.50000 * red - 0.41869 * grn - 0.08131 * blu);
+}
+
+
+
+void 
+pnm_YCbCr_to_rgbtuple(const struct pam * const pamP,
+                      tuple              const tuple,
+                      double             const Y,
+                      double             const Cb, 
+                      double             const Cr,
+                      int *              const overflowP) {
+
+    double rgb[3];
+    unsigned int plane;
+    bool overflow;
+
+    rgb[PAM_RED_PLANE] = Y + 1.4022 * Cr + .5;
+    rgb[PAM_GRN_PLANE] = Y - 0.7145 * Cr - 0.3456 * Cb + .5;
+    rgb[PAM_BLU_PLANE] = Y + 1.7710 * Cb + .5;
+
+    overflow = FALSE;  /* initial assumption */
+
+    for (plane = 0; plane < 3; ++plane) {
+        if (rgb[plane] > pamP->maxval) {
+            overflow = TRUE;
+            tuple[plane] = pamP->maxval;
+        } else if (rgb[plane] < 0.0) {
+            overflow = TRUE;
+            tuple[plane] = 0;
+        } else 
+            tuple[plane] = (sample)rgb[plane];
+    }
+    if (overflowP)
+        *overflowP = overflow;
+}
+
+
+