Add RGBnoQUANT option to PS_COLOR_MODEL

doc/rst/source/gmt.conf.rst

@@ -1091,8 +1091,13 @@ PostScript Parameters
         with standard fonts.
 
     **PS_COLOR_MODEL**
-        Determines whether PostScript output should use **RGB**, **HSV**, **CMYK**,
-        or **GRAY** when specifying color [default is **rgb**]. Note if **HSV**
+        Determines whether PostScript output should use **RGB**, **RGBnoQUANT**,
+        **HSV**, **CMYK**, or **GRAY** when specifying color [default is **rgb**].
+        **RGBnoQUANT** uses
+        normal RGB colors but forces direct RGB raster output instead of indexed
+        images. This may increase file size and is intended for compatibility with
+        third-party PostScript/PDF editors that have problems with indexed images.
+        Note if **HSV**
         is selected it does not apply to images which in that case uses **RGB**.
         When selecting **GRAY**, all colors will be converted to gray scale using
         YIQ (television) conversion.

src/gmt_defaults.h

@@ -192,6 +192,7 @@ struct GMT_DEFAULTS {
 	double ps_transparency;			/* Later transparency [0] */
 	double ps_penwidth;			/* Current pen width */
 	unsigned int ps_color_mode;		/* Postscript encoding of color [PSL_RGB | PSL_CMYK | PSL_HSV | PSL_GRAY] */
+	bool ps_color_no_quantization;	/* Skip RGB image quantization and indexed-color output [false] */
 	unsigned int ps_copies;		/* How man copies of each plot [>=1] [GMT4 COMPATIBILITY ONLY] */
 	int ps_media;			/* Default paper media [25(Letter)]; negative if custom size */
 	unsigned int ps_orientation;			/* Orientation of page [PSL_LANDSCAPE (0)] or PSL_PORTRAIT (1) */

src/gmt_init.c

@@ -6972,6 +6972,7 @@ EXTERN_MSC void gmtinit_conf_classic (struct GMT_CTRL *GMT) {
 	gmtinit_load_encoding (GMT);
 	/* PS_COLOR_MODEL */
 	GMT->current.setting.ps_color_mode = PSL_RGB;
+	GMT->current.setting.ps_color_no_quantization = false;
 	/* PS_IMAGE_COMPRESS */
 	if (GMT->PSL) {	/* Only when using PSL in this session */
 #ifdef HAVE_ZLIB
@@ -11750,14 +11751,26 @@ unsigned int gmtlib_setparameter (struct GMT_CTRL *GMT, const char *keyword, cha
 			gmt_M_compat_translate ("PS_COLOR_MODEL");
 			break;
 		case GMTCASE_PS_COLOR_MODEL:
-			if (!strcmp (lower_value, "rgb"))
+			if (!strcmp (lower_value, "rgb")) {
 				GMT->current.setting.ps_color_mode = PSL_RGB;
-			else if (!strcmp (lower_value, "cmyk"))
+				GMT->current.setting.ps_color_no_quantization = false;
+			}
+			else if (!strcmp (lower_value, "rgbnoquant")) {
+				GMT->current.setting.ps_color_mode = PSL_RGB;
+				GMT->current.setting.ps_color_no_quantization = true;
+			}
+			else if (!strcmp (lower_value, "cmyk")) {
 				GMT->current.setting.ps_color_mode = PSL_CMYK;
-			else if (!strcmp (lower_value, "hsv"))
+				GMT->current.setting.ps_color_no_quantization = false;
+			}
+			else if (!strcmp (lower_value, "hsv")) {
 				GMT->current.setting.ps_color_mode = PSL_HSV;
-			else if (!strcmp (lower_value, "gray") || !strcmp (lower_value, "grey"))
+				GMT->current.setting.ps_color_no_quantization = false;
+			}
+			else if (!strcmp (lower_value, "gray") || !strcmp (lower_value, "grey")) {
 				GMT->current.setting.ps_color_mode = PSL_GRAY;
+				GMT->current.setting.ps_color_no_quantization = false;
+			}
 			else
 				error = true;
 			break;
@@ -13261,7 +13274,9 @@ char *gmtlib_getparameter (struct GMT_CTRL *GMT, const char *keyword) {
 			else { error = gmtinit_badvalreport (GMT, keyword); break; }	/* Not recognized so give error message */
 			/* Intentionally fall through */
 		case GMTCASE_PS_COLOR_MODEL:
-			if (GMT->current.setting.ps_color_mode == PSL_RGB)
+			if (GMT->current.setting.ps_color_no_quantization)
+				strcpy (value, "rgbnoquant");
+			else if (GMT->current.setting.ps_color_mode == PSL_RGB)
 				strcpy (value, "rgb");
 			else if (GMT->current.setting.ps_color_mode == PSL_CMYK)
 				strcpy (value, "cmyk");

src/gmt_keywords.txt

@@ -152,7 +152,7 @@ PROJ_SCALE_FACTOR		# Scale factor for UTM maps
 # PS Group:	PostScript settings
 #-------------------------------------------------------
 PS_CHAR_ENCODING		# Character encoding vector to use in PS plots
-PS_COLOR_MODEL			# Color model in use (RGB, HSV, CMYK, GRAY)
+PS_COLOR_MODEL			# Color model in use (RGB, RGBnoQUANT, HSV, CMYK, GRAY)
 PS_DPI				# The dots-pr-inch setting [obsolete - not in gmt.conf]
 PS_IMAGE_COMPRESS		# Compression algorithm for images
 PS_LINE_CAP			# Line cap setting
@@ -177,4 +177,4 @@ TIME_REPORT			# Controls time or elapsed run-time stamp in messages
 TIME_UNIT			# Unit of time measurement
 TIME_SYSTEM			# Shortcut to setting TIME_EPOCH/UNIT [does not go in gmt.conf]
 TIME_WEEK_START			# Day a new week starts on
-TIME_Y2K_OFFSET_YEAR		# For 2-digit years to separate 1900 and 2000 centuries
+TIME_Y2K_OFFSET_YEAR		# For 2-digit years to separate 1900 and 2000 centuries

src/gmt_plot.c

@@ -9319,6 +9319,7 @@ struct PSL_CTRL *gmt_plotinit (struct GMT_CTRL *GMT, struct GMT_OPTION *options)
 	else
 		snprintf (GMT->current.ps.title, GMT_LEN256, "GMT v%s Document from %s", GMT_VERSION, GMT->init.module_name);
 
+	PSL->internal.no_quantization = GMT->current.setting.ps_color_no_quantization;
 	PSL_beginplot (PSL, fp, GMT->current.setting.ps_orientation|write_to_mem|switch_charset, O_active, GMT->current.setting.ps_color_mode,
 		GMT->current.ps.origin, GMT->current.setting.map_origin, media_size, GMT->current.ps.title, fno);
 

src/postscriptlight.c

@@ -3888,7 +3888,9 @@ int PSL_plotcolorimage (struct PSL_CTRL *PSL, double x, double y, double xsize,
 	/* Colormask or interpolate */
 	it = nx < 0 ? 1 : (nbits < 0 ? 2 : 0);
 
-	if (PSL->internal.color_mode != PSL_GRAY && (image = psl_makecolormap (PSL, buffer, nx, ny, nbits))) {
+	if (!PSL->internal.no_quantization &&
+	    PSL->internal.color_mode != PSL_GRAY &&
+	    (image = psl_makecolormap (PSL, buffer, nx, ny, nbits))) {
 		/* Creation of colormap was successful */
 		nbits = psl_bitreduce (PSL, image->buffer, nx, ny, image->colormap->ncolors);
 

src/postscriptlight.h

@@ -45,6 +45,7 @@ extern "C" {
 /* Declaration modifiers for DLL support (MSC et al) */
 #include "declspec.h"
 
+#include <stdbool.h>
 #include <stdio.h>
 
 #define PSL_MaxOpStack_Size	300000	/* As of GhostSCript 9.50; see declaration in gs_init.ps */
@@ -401,6 +402,7 @@ struct PSL_CTRL {
 		int deflate_level; 		/* Compression level for DEFLATE (1-9, default 0) */
 		int call_level; 		/* Level in a series of module calls from GMT */
 		int color_mode;			/* 0 = rgb, 1 = cmyk, 2 = hsv (only 1-2 for images)	*/
+		bool no_quantization;		/* Skip RGB image quantization and indexed-color output [false] */
 		int line_cap;			/* 0, 1, or 2 for butt, round, or square [butt]	*/
 		int line_join;			/* 0, 1, or 2 for miter, arc, or bevel [miter]	*/
 		int miter_limit;		/* Acute angle threshold 0-180; 0 means PS default [0] */

test/postscriptlight/rgbnoquant.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+#
+# Purpose: Verify RGBnoQUANT bypasses PSL indexed-color image optimization
+# GMT modules: gmt
+#
+printf 'P6\n4 4\n255\n' > colors.ppm
+printf '\377\000\000\000\377\000\000\000\377\377\377\000' >> colors.ppm
+printf '\000\377\000\000\000\377\377\377\000\377\000\000' >> colors.ppm
+printf '\000\000\377\377\377\000\377\000\000\000\377\000' >> colors.ppm
+printf '\377\377\000\377\000\000\000\377\000\000\000\377' >> colors.ppm
+
+# Default RGB keeps the existing indexed-color and bit-reduction path.
+gmt set PS_COLOR_MODEL RGB
+[ "$(gmt get PS_COLOR_MODEL)" = "rgb" ] || echo "RGB setting did not round-trip" >> fail
+gmt psimage colors.ppm -R0/4/0/4 -JX4c > indexed.ps
+grep -Fq "/Indexed /DeviceRGB" indexed.ps || echo "RGB image was not indexed" >> fail
+grep -Fq "/Decode [0 3]" indexed.ps || echo "RGB image was not bit-reduced" >> fail
+
+# Case-insensitive RGBnoQUANT must use the existing direct DeviceRGB path.
+gmt set PS_COLOR_MODEL RgBnOqUaNt
+[ "$(gmt get PS_COLOR_MODEL)" = "rgbnoquant" ] || echo "RGBnoQUANT setting did not round-trip" >> fail
+gmt psimage colors.ppm -R0/4/0/4 -JX4c > direct.ps
+grep -Fq "/Indexed /DeviceRGB" direct.ps && echo "RGBnoQUANT image was indexed" >> fail
+grep -Fq "/DeviceRGB setcolorspace" direct.ps || echo "RGBnoQUANT image was not direct DeviceRGB" >> fail
+grep -Fq "/Decode [0 1 0 1 0 1]" direct.ps || echo "RGBnoQUANT image was not 24 bit" >> fail
+
+# Switching back to RGB must reset the no-quantization flag.
+gmt set PS_COLOR_MODEL rgb
+gmt psimage colors.ppm -R0/4/0/4 -JX4c > restored.ps
+grep -Fq "/Indexed /DeviceRGB" restored.ps || echo "RGB did not restore indexed output" >> fail