Move transfer functions to 16 bits.dev-robin

This means that in 'deep' modes, we sample them in 257 places
(0000,0100,....ff00,ffff) rather than 256 (00,01,...ff), and
in 16 bits rather than 8. We also interpolate them on reading.

This in turn increases the size of the data put into the clist.

1 files changed, 25 insertions, 4 deletions

diff --git a/base/gstrans.c b/base/gstrans.c
index 68b603ccc..75f83288a 100644
--- a/base/gstrans.c
+++ b/base/gstrans.c
@@ -548,6 +548,10 @@ gs_begin_transparency_mask(gs_gstate * pgs,
     int i, code;
     gs_color_space *blend_color_space;
     gsicc_manager_t *icc_manager = pgs->icc_manager;
+    bool has_tags = device_encodes_tags(pgs->device);
+    int bits_per_comp = ((pgs->device->color_info.depth - has_tags*8) /
+                         pgs->device->color_info.num_components);
+    int deep = bits_per_comp > 8;
 
     if (check_for_nontrans_pattern(pgs,
                   (unsigned char *)"gs_pop_transparency_state")) {
@@ -601,12 +605,29 @@ gs_begin_transparency_mask(gs_gstate * pgs,
                   (ptmp->TransferFunction == mask_transfer_identity ? "no TR" :
                    "has TR"));
         /* Sample the transfer function */
-        for (i = 0; i < MASK_TRANSFER_FUNCTION_SIZE; i++) {
-            float in = (float)(i * (1.0 / (MASK_TRANSFER_FUNCTION_SIZE - 1)));
+        /* For non-deep cases, we sample at 00,01,02..fe,ff.
+         * For deep cases, we sample from 0000,0100,0200..fe00,ff00 and a final one at ffff.
+         * This enables us to interpolate easily.
+         */
+        if (deep) {
+            uint16_t *trans16 = (uint16_t *)params.transfer_fn;
             float out;
+            for (i = 0; i < MASK_TRANSFER_FUNCTION_SIZE; i++) {
+                float in = (float)(i * (1.0 / MASK_TRANSFER_FUNCTION_SIZE));
 
-            ptmp->TransferFunction(in, &out, ptmp->TransferFunction_data);
-            params.transfer_fn[i] = (byte)floor((double)(out * 255 + 0.5));
+                ptmp->TransferFunction(in, &out, ptmp->TransferFunction_data);
+                trans16[i] = (uint16_t)floor((double)(out * 65535 + 0.5));
+            }
+            ptmp->TransferFunction(1.0, &out, ptmp->TransferFunction_data);
+            trans16[MASK_TRANSFER_FUNCTION_SIZE] = (uint16_t)floor((double)(out * 65535 + 0.5));
+        } else {
+            for (i = 0; i < MASK_TRANSFER_FUNCTION_SIZE; i++) {
+                float in = (float)(i * (1.0 / (MASK_TRANSFER_FUNCTION_SIZE - 1)));
+                float out;
+
+                ptmp->TransferFunction(in, &out, ptmp->TransferFunction_data);
+                params.transfer_fn[i] = (byte)floor((double)(out * 255 + 0.5));
+            }
         }
         /* Note:  This function is called during the c-list writer side. */
         if ( blend_color_space->cmm_icc_profile_data != NULL ) {