path: root/gs/src/gxcmap.c

/* Copyright (C) 1992, 1996, 1997, 1998, 1999 Aladdin Enterprises.  All rights reserved.

   This software is licensed to a single customer by Artifex Software Inc.
   under the terms of a specific OEM agreement.
 */

/*$RCSfile$ $Revision$ */
/* Color mapping for Ghostscript */
#include "gx.h"
#include "gserrors.h"
#include "gsccolor.h"
#include "gxalpha.h"
#include "gxcspace.h"
#include "gxfarith.h"
#include "gxfrac.h"
#include "gxdcconv.h"
#include "gxdevice.h"
#include "gxcmap.h"
#include "gxlum.h"
#include "gzstate.h"
#include "gxdither.h"

/* Structure descriptor */
public_st_device_color();
private 
ENUM_PTRS_WITH(device_color_enum_ptrs, gx_device_color *cptr)
{
    return ENUM_USING(*cptr->type->stype, vptr, size, index);
}
ENUM_PTRS_END
private RELOC_PTRS_WITH(device_color_reloc_ptrs, gx_device_color *cptr)
{
    RELOC_USING(*cptr->type->stype, vptr, size);
}
RELOC_PTRS_END

/* ------ Trace device mapping procedures ------ */

/* If DEBUG is defined, these procedures substitute for direct calls */
/* on the device map_{rgb,cmyk}_color procedures. */

gx_color_index
gx_proc_map_rgb_color(gx_device * dev,
		    gx_color_value vr, gx_color_value vg, gx_color_value vb)
{
    gx_color_index cindex =
    (*dev_proc(dev, map_rgb_color)) (dev, vr, vg, vb);

    if_debug5('C', "%s [C]RGB %u,%u,%u -> color 0x%lx\n",
	      dev->dname, (uint) vr, (uint) vg, (uint) vb, (ulong) cindex);
    return cindex;
}

gx_color_index
gx_proc_map_rgb_alpha_color(gx_device * dev,
 gx_color_value vr, gx_color_value vg, gx_color_value vb, gx_color_value va)
{
    gx_color_index cindex =
    (*dev_proc(dev, map_rgb_alpha_color)) (dev, vr, vg, vb, va);

    if_debug6('C', "[C]%s RGBA %u,%u,%u,%u -> color 0x%lx\n",
	      dev->dname, (uint) vr, (uint) vg, (uint) vb, (uint) va,
	      (ulong) cindex);
    return cindex;
}

gx_color_index
gx_proc_map_cmyk_color(gx_device * dev,
 gx_color_value vc, gx_color_value vm, gx_color_value vy, gx_color_value vk)
{
    gx_color_index cindex =
    (*dev_proc(dev, map_cmyk_color)) (dev, vc, vm, vy, vk);

    if_debug6('C', "[C]%s CMYK %u,%u,%u,%u -> color 0x%lx\n",
	      dev->dname, (uint) vc, (uint) vm, (uint) vy, (uint) vk,
	      (ulong) cindex);
    return cindex;
}

/* ---------------- Device color rendering ---------------- */

private cmap_proc_gray(cmap_gray_halftoned);
private cmap_proc_gray(cmap_gray_direct);
private cmap_proc_gray(cmap_gray_to_rgb_halftoned);
private cmap_proc_gray(cmap_gray_to_rgb_direct);
private cmap_proc_gray(cmap_gray_to_cmyk_halftoned);
private cmap_proc_gray(cmap_gray_to_cmyk_direct);
private cmap_proc_rgb(cmap_rgb_halftoned);
private cmap_proc_rgb(cmap_rgb_direct);
private cmap_proc_rgb(cmap_rgb_to_gray_halftoned);
private cmap_proc_rgb(cmap_rgb_to_gray_direct);
private cmap_proc_rgb(cmap_rgb_to_cmyk);

#define cmap_cmyk_halftoned cmap_cmyk_direct
private cmap_proc_cmyk(cmap_cmyk_direct);
private cmap_proc_cmyk(cmap_cmyk_to_gray);
private cmap_proc_cmyk(cmap_cmyk_to_rgb);
private cmap_proc_rgb_alpha(cmap_rgb_alpha_halftoned);
private cmap_proc_rgb_alpha(cmap_rgb_alpha_direct);

/* Procedure names are only guaranteed unique to 23 characters.... */
private cmap_proc_rgb_alpha(cmap_rgb_alpha2gray_halftoned);
private cmap_proc_rgb_alpha(cmap_rgb_alpha2gray_direct);
private cmap_proc_rgb_alpha(cmap_rgb_alpha_to_cmyk);

private const gx_color_map_procs
      cmap_gray_few =
{cmap_gray_halftoned, cmap_rgb_to_gray_halftoned, cmap_cmyk_to_gray,
 cmap_rgb_alpha2gray_halftoned
},    cmap_gray_many =
{cmap_gray_direct, cmap_rgb_to_gray_direct, cmap_cmyk_to_gray,
 cmap_rgb_alpha2gray_direct
},    cmap_rgb_few =
{cmap_gray_to_rgb_halftoned, cmap_rgb_halftoned, cmap_cmyk_to_rgb,
 cmap_rgb_alpha_halftoned
},    cmap_rgb_many =
{cmap_gray_to_rgb_direct, cmap_rgb_direct, cmap_cmyk_to_rgb,
 cmap_rgb_alpha_direct
},    cmap_cmyk_few =
{cmap_gray_to_cmyk_halftoned, cmap_rgb_to_cmyk, cmap_cmyk_halftoned,
 cmap_rgb_alpha_to_cmyk
},    cmap_cmyk_many =
{cmap_gray_to_cmyk_direct, cmap_rgb_to_cmyk, cmap_cmyk_direct,
 cmap_rgb_alpha_to_cmyk
};

const gx_color_map_procs *const cmap_procs_default = &cmap_gray_many;

private const gx_color_map_procs *const cmap_few[] =
{
    0, &cmap_gray_few, 0, &cmap_rgb_few, &cmap_cmyk_few
};

private const gx_color_map_procs *const cmap_many[] =
{
    0, &cmap_gray_many, 0, &cmap_rgb_many, &cmap_cmyk_many
};

/* Determine the color mapping procedures for a device. */
/* Note that the default procedure doesn't consult the imager state. */
const gx_color_map_procs *
gx_get_cmap_procs(const gs_imager_state *pis, const gx_device * dev)
{
    return (pis->get_cmap_procs)(pis, dev);
}
const gx_color_map_procs *
gx_default_get_cmap_procs(const gs_imager_state *pis, const gx_device * dev)
{
    return (gx_device_must_halftone(dev) ? cmap_few : cmap_many)
	[dev->color_info.num_components];
}

/* Set the color mapping procedures in the graphics state. */
void
gx_set_cmap_procs(gs_imager_state * pis, const gx_device * dev)
{
    pis->cmap_procs = gx_get_cmap_procs(pis, dev);
}

/* Remap the color in the graphics state. */
int
gx_remap_color(gs_state * pgs)
{
    const gs_color_space *pcs = pgs->color_space;

    /* The current color in the graphics state is always used for */
    /* the texture, never for the source. */
    return (*pcs->type->remap_color) (pgs->ccolor, pcs, pgs->dev_color,
				      (gs_imager_state *) pgs, pgs->device,
				      gs_color_select_texture);
}

/* Indicate that a color space has no underlying concrete space. */
const gs_color_space *
gx_no_concrete_space(const gs_color_space * pcs, const gs_imager_state * pis)
{
    return NULL;
}

/* Indicate that a color space is concrete. */
const gs_color_space *
gx_same_concrete_space(const gs_color_space * pcs, const gs_imager_state * pis)
{
    return pcs;
}

/* Indicate that a color cannot be concretized. */
int
gx_no_concretize_color(const gs_client_color * pcc, const gs_color_space * pcs,
		       frac * pconc, const gs_imager_state * pis)
{
    return_error(gs_error_rangecheck);
}

/* By default, remap a color by concretizing it and then */
/* remapping the concrete color. */
int
gx_default_remap_color(const gs_client_color * pcc, const gs_color_space * pcs,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
		       gs_color_select_t select)
{
    frac conc[GS_CLIENT_COLOR_MAX_COMPONENTS];
    const gs_color_space *pconcs;
    int code = (*pcs->type->concretize_color)(pcc, pcs, conc, pis);

    if (code < 0)
	return code;
    pconcs = cs_concrete_space(pcs, pis);
    return (*pconcs->type->remap_concrete_color)(conc, pdc, pis, dev, select);
}

/* Color remappers for the standard color spaces. */
/* Note that we use D... instead of Device... in some places because */
/* gcc under VMS only retains 23 characters of procedure names. */

#define unit_frac(v, ftemp)\
  (ftemp = (v),\
   (is_fneg(ftemp) ? frac_0 : is_fge1(ftemp) ? frac_1 : float2frac(ftemp)))

/* DeviceGray */
int
gx_concretize_DeviceGray(const gs_client_color * pc, const gs_color_space * pcs,
			 frac * pconc, const gs_imager_state * pis)
{
    float ftemp;

    pconc[0] = unit_frac(pc->paint.values[0], ftemp);
    return 0;
}
int
gx_remap_concrete_DGray(const frac * pconc,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
			gs_color_select_t select)
{
    if (pis->alpha == gx_max_color_value)
	(*pis->cmap_procs->map_gray)
	    (pconc[0], pdc, pis, dev, select);
    else
	(*pis->cmap_procs->map_rgb_alpha)
	    (pconc[0], pconc[0], pconc[0], cv2frac(pis->alpha),
	     pdc, pis, dev, select);
    return 0;
}
int
gx_remap_DeviceGray(const gs_client_color * pc, const gs_color_space * pcs,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
		    gs_color_select_t select)
{
    float ftemp;
    frac fgray = unit_frac(pc->paint.values[0], ftemp);

    if (pis->alpha == gx_max_color_value)
	(*pis->cmap_procs->map_gray)
	    (fgray, pdc, pis, dev, select);
    else
	(*pis->cmap_procs->map_rgb_alpha)
	    (fgray, fgray, fgray, cv2frac(pis->alpha), pdc, pis, dev, select);
    return 0;
}

/* DeviceRGB */
int
gx_concretize_DeviceRGB(const gs_client_color * pc, const gs_color_space * pcs,
			frac * pconc, const gs_imager_state * pis)
{
    float ftemp;

    pconc[0] = unit_frac(pc->paint.values[0], ftemp);
    pconc[1] = unit_frac(pc->paint.values[1], ftemp);
    pconc[2] = unit_frac(pc->paint.values[2], ftemp);
    return 0;
}
int
gx_remap_concrete_DRGB(const frac * pconc,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
		       gs_color_select_t select)
{
    if (pis->alpha == gx_max_color_value)
	gx_remap_concrete_rgb(pconc[0], pconc[1], pconc[2],
			      pdc, pis, dev, select);
    else
	gx_remap_concrete_rgb_alpha(pconc[0], pconc[1], pconc[2],
				    cv2frac(pis->alpha),
				    pdc, pis, dev, select);
    return 0;
}
int
gx_remap_DeviceRGB(const gs_client_color * pc, const gs_color_space * pcs,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
		   gs_color_select_t select)
{
    float ftemp;
    frac fred = unit_frac(pc->paint.values[0], ftemp), fgreen = unit_frac(pc->paint.values[1], ftemp),
         fblue = unit_frac(pc->paint.values[2], ftemp);

    if (pis->alpha == gx_max_color_value)
	gx_remap_concrete_rgb(fred, fgreen, fblue,
			      pdc, pis, dev, select);
    else
	gx_remap_concrete_rgb_alpha(fred, fgreen, fblue, cv2frac(pis->alpha),
				    pdc, pis, dev, select);
    return 0;
}

/* DeviceCMYK */
int
gx_concretize_DeviceCMYK(const gs_client_color * pc, const gs_color_space * pcs,
			 frac * pconc, const gs_imager_state * pis)
{
    float ftemp;

    pconc[0] = unit_frac(pc->paint.values[0], ftemp);
    pconc[1] = unit_frac(pc->paint.values[1], ftemp);
    pconc[2] = unit_frac(pc->paint.values[2], ftemp);
    pconc[3] = unit_frac(pc->paint.values[3], ftemp);
    return 0;
}
int
gx_remap_concrete_DCMYK(const frac * pconc,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
			gs_color_select_t select)
{
/****** IGNORE alpha ******/
    gx_remap_concrete_cmyk(pconc[0], pconc[1], pconc[2], pconc[3], pdc,
			   pis, dev, select);
    return 0;
}
int
gx_remap_DeviceCMYK(const gs_client_color * pc, const gs_color_space * pcs,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
		    gs_color_select_t select)
{
/****** IGNORE alpha ******/
    float ft0, ft1, ft2, ft3;

    gx_remap_concrete_cmyk(unit_frac(pc->paint.values[0], ft0),
			   unit_frac(pc->paint.values[1], ft1),
			   unit_frac(pc->paint.values[2], ft2),
			   unit_frac(pc->paint.values[3], ft3),
			   pdc, pis, dev, select);
    return 0;
}

/* ------ Render Gray color. ------ */

private void
cmap_gray_halftoned(frac gray, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    if (gx_render_gray(gx_map_color_frac(pis, gray, effective_transfer.colored.gray), pdc, pis, dev, select) == 1)
	gx_color_load_select(pdc, pis, dev, select);
}

private void
cmap_gray_direct(frac gray, gx_device_color * pdc, const gs_imager_state * pis,
		 gx_device * dev, gs_color_select_t select)
{
    frac mgray = gx_map_color_frac(pis, gray, effective_transfer.colored.gray);
    gx_color_value cv_gray = frac2cv(mgray);
    gx_color_index color =
    (pis->alpha == gx_max_color_value ?
     gx_map_rgb_color(dev, cv_gray, cv_gray, cv_gray) :
     gx_map_rgb_alpha_color(dev, cv_gray, cv_gray, cv_gray, pis->alpha));

    if (color == gx_no_color_index) {
	if (gx_render_gray(mgray, pdc, pis, dev, select) == 1)
	    gx_color_load_select(pdc, pis, dev, select);
	return;
    }
    color_set_pure(pdc, color);
}

private void
cmap_gray_to_rgb_halftoned(frac gray, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    cmap_rgb_halftoned(gray, gray, gray, pdc, pis, dev, select);
}

private void
cmap_gray_to_rgb_direct(frac gray, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    cmap_rgb_direct(gray, gray, gray, pdc, pis, dev, select);
}

private void
cmap_gray_to_cmyk_halftoned(frac gray, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{				/*
				 * Per the last paragraph of section 6.3 (p. 309) of the
				 * PostScript Language Reference Manual, 2nd Edition,
				 * we must bypass the C, M, and Y transfer functions in this case.
				 */
    frac mgray = gx_map_color_frac(pis, gray, effective_transfer.colored.gray);

    if (gx_render_gray(mgray, pdc, pis, dev, select) == 1)
	gx_color_load_select(pdc, pis, dev, select);
}

private void
cmap_gray_to_cmyk_direct(frac gray, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{				/*
				 * Per the last paragraph of section 6.3 (p. 309) of the
				 * PostScript Language Reference Manual, 2nd Edition,
				 * we must bypass the C, M, and Y transfer functions in this case.
				 */
    frac mgray = gx_map_color_frac(pis, gray, effective_transfer.colored.gray);
    frac mblack = frac_1 - mgray;
    gx_color_index color =
    gx_map_cmyk_color(dev,
		      frac2cv(frac_0), frac2cv(frac_0),
		      frac2cv(frac_0), frac2cv(mblack));

    if (color != gx_no_color_index) {
	color_set_pure(pdc, color);
	return;
    }
    if (gx_render_gray(mgray, pdc, pis, dev, select) == 1)
	gx_color_load_select(pdc, pis, dev, select);
}

/* ------ Render RGB color. ------ */

/*
 * This code should test r == g and g == b and then use the gray
 * rendering procedures.  The Adobe documentation allows this:
 * conversion between color spaces occurs before the transfer function
 * and halftoning.  However, output from FrameMaker (mis)uses the
 * transfer function to provide the equivalent of indexed color;
 * it requires the color components to be passed through unchanged.
 * For this reason, we have to make the check after the transfer
 * function rather than before.
 *
 * Since this procedure is used so heavily, we duplicate most of its code
 * rather than making a text for color_info.max_color >= 31.
 */

private void
cmap_rgb_halftoned(frac r, frac g, frac b, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    frac mred = gx_map_color_frac(pis, r, effective_transfer.colored.red);
    frac mgreen = gx_map_color_frac(pis, g, effective_transfer.colored.green);
    frac mblue = gx_map_color_frac(pis, b, effective_transfer.colored.blue);

    if ((mred == mgreen && mred == mblue ?	/* gray shade */
	 gx_render_gray(mred, pdc, pis, dev, select) :
	 gx_render_rgb(mred, mgreen, mblue, pdc, pis, dev, select)) == 1)
	gx_color_load_select(pdc, pis, dev, select);
}

private void
cmap_rgb_direct(frac r, frac g, frac b, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    frac mred = gx_map_color_frac(pis, r, effective_transfer.colored.red);
    frac mgreen = gx_map_color_frac(pis, g, effective_transfer.colored.green);
    frac mblue = gx_map_color_frac(pis, b, effective_transfer.colored.blue);
    gx_color_index color =
    (pis->alpha == gx_max_color_value ?
     gx_map_rgb_color(dev, frac2cv(mred), frac2cv(mgreen),
		      frac2cv(mblue)) :
     gx_map_rgb_alpha_color(dev, frac2cv(mred), frac2cv(mgreen),
			    frac2cv(mblue), pis->alpha));

    if (color != gx_no_color_index) {
	color_set_pure(pdc, color);
	return;
    }
    if ((mred == mgreen && mred == mblue ?	/* gray shade */
	 gx_render_gray(mred, pdc, pis, dev, select) :
	 gx_render_rgb(mred, mgreen, mblue, pdc, pis, dev, select)) == 1)
	gx_color_load_select(pdc, pis, dev, select);
}

private void
cmap_rgb_to_gray_halftoned(frac r, frac g, frac b, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    cmap_gray_halftoned(color_rgb_to_gray(r, g, b, pis), pdc, pis, dev, select);
}

private void
cmap_rgb_to_gray_direct(frac r, frac g, frac b, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    cmap_gray_direct(color_rgb_to_gray(r, g, b, pis), pdc, pis, dev, select);
}

private void
cmap_rgb_to_cmyk(frac r, frac g, frac b, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    frac cmyk[4];

    color_rgb_to_cmyk(r, g, b, pis, cmyk);
    (*pis->cmap_procs->map_cmyk) (cmyk[0], cmyk[1], cmyk[2], cmyk[3], pdc, pis, dev, select);
}

/* ------ Render CMYK color. ------ */

private void
cmap_cmyk_to_gray(frac c, frac m, frac y, frac k, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    (*pis->cmap_procs->map_gray) (color_cmyk_to_gray(c, m, y, k, pis), pdc, pis, dev, select);
}

private void
cmap_cmyk_direct(frac c, frac m, frac y, frac k, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    frac mcyan = frac_1 - gx_map_color_frac(pis, frac_1 - c, effective_transfer.colored.red);
    frac mmagenta = frac_1 - gx_map_color_frac(pis, frac_1 - m, effective_transfer.colored.green);
    frac myellow = frac_1 - gx_map_color_frac(pis, frac_1 - y, effective_transfer.colored.blue);
    frac mblack = frac_1 - gx_map_color_frac(pis, frac_1 - k, effective_transfer.colored.gray);

    /* We make a test for direct vs. halftoned, rather than */
    /* duplicating most of the code of this procedure. */
    if (!gx_color_device_must_halftone(dev)) {
	gx_color_index color =
	gx_map_cmyk_color(dev,
			  frac2cv(mcyan), frac2cv(mmagenta),
			  frac2cv(myellow), frac2cv(mblack));

	if (color != gx_no_color_index) {
	    color_set_pure(pdc, color);
	    return;
	}
    }
    /* Don't convert colors with C = M = Y to gray shades: */
    /* on a CMYK device, this may produce quite different output. */
    if (gx_render_cmyk(mcyan, mmagenta, myellow, mblack, pdc, pis, dev, select) == 1)
	gx_color_load_select(pdc, pis, dev, select);
}

private void
cmap_cmyk_to_rgb(frac c, frac m, frac y, frac k, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    frac rgb[3];

    color_cmyk_to_rgb(c, m, y, k, pis, rgb);
    (*pis->cmap_procs->map_rgb) (rgb[0], rgb[1], rgb[2], pdc, pis, dev, select);
}

/* ------ Render RGB+alpha color. ------ */

#ifdef PREMULTIPLY_TOWARDS_WHITE
#  define alpha_bias_value frac_1 - alpha
#  define alpha_bias(v) ((v) + alpha_bias_value
#else
#  define alpha_bias(v) (v)
#endif

private void
cmap_rgb_alpha2gray_halftoned(frac r, frac g, frac b, frac alpha,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
			      gs_color_select_t select)
{
    frac gray = color_rgb_to_gray(r, g, b, pis);

    if (alpha != frac_1)	/* premultiply */
	gray = alpha_bias((frac) ((long)gray * alpha / frac_1));
    if (gx_render_gray_alpha(gx_map_color_frac(pis, gray, effective_transfer.colored.gray), frac2cv(alpha), pdc, pis, dev, select) == 1)
	gx_color_load_select(pdc, pis, dev, select);
}

private void
cmap_rgb_alpha2gray_direct(frac r, frac g, frac b, frac alpha,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
			   gs_color_select_t select)
{
    frac gray = color_rgb_to_gray(r, g, b, pis);

    if (alpha != frac_1)	/* premultiply */
	gray = alpha_bias((frac) ((long)gray * alpha / frac_1));
    {
	frac mgray =
	gx_map_color_frac(pis, gray, effective_transfer.colored.gray);
	gx_color_value cv_gray = frac2cv(mgray);
	gx_color_index color =
	(alpha == frac_1 ?
	 gx_map_rgb_color(dev, cv_gray, cv_gray, cv_gray) :
	 gx_map_rgb_alpha_color(dev, cv_gray, cv_gray, cv_gray, frac2cv(alpha)));

	if (color == gx_no_color_index) {
	    if (gx_render_gray_alpha(mgray, frac2cv(alpha), pdc, pis, dev, select) == 1)
		gx_color_load_select(pdc, pis, dev, select);
	    return;
	}
	color_set_pure(pdc, color);
    }
}

private void
cmap_rgb_alpha_halftoned(frac r, frac g, frac b, frac alpha,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
			 gs_color_select_t select)
{
    frac red = r, green = g, blue = b;

    if (alpha != frac_1) {	/* premultiply */
	red = alpha_bias((frac) ((long)red * alpha / frac_1));
	green = alpha_bias((frac) ((long)green * alpha / frac_1));
	blue = alpha_bias((frac) ((long)blue * alpha / frac_1));
    } {
	frac mred =
	gx_map_color_frac(pis, red, effective_transfer.colored.red);
	frac mgreen =
	gx_map_color_frac(pis, green, effective_transfer.colored.green);
	frac mblue =
	gx_map_color_frac(pis, blue, effective_transfer.colored.blue);
	gx_color_value cv_alpha = frac2cv(alpha);

	if ((mred == mgreen && mred == mblue ?	/* gray shade */
	     gx_render_gray_alpha(mred, cv_alpha, pdc, pis, dev, select) :
	     gx_render_rgb_alpha(mred, mgreen, mblue, cv_alpha, pdc, pis, dev, select)) == 1)
	    gx_color_load_select(pdc, pis, dev, select);
    }
}

private void
cmap_rgb_alpha_direct(frac r, frac g, frac b, frac alpha, gx_device_color * pdc,
     const gs_imager_state * pis, gx_device * dev, gs_color_select_t select)
{
    frac red = r, green = g, blue = b;

    if (alpha != frac_1) {	/* premultiply */
	red = alpha_bias((frac) ((long)red * alpha / frac_1));
	green = alpha_bias((frac) ((long)green * alpha / frac_1));
	blue = alpha_bias((frac) ((long)blue * alpha / frac_1));
    } {
	frac mred =
	gx_map_color_frac(pis, red, effective_transfer.colored.red);
	frac mgreen =
	gx_map_color_frac(pis, green, effective_transfer.colored.green);
	frac mblue =
	gx_map_color_frac(pis, blue, effective_transfer.colored.blue);
	gx_color_value cv_alpha = frac2cv(alpha);
	gx_color_index color =
	(cv_alpha == gx_max_color_value ?
	 gx_map_rgb_color(dev, frac2cv(mred), frac2cv(mgreen),
			  frac2cv(mblue)) :
	 gx_map_rgb_alpha_color(dev, frac2cv(mred), frac2cv(mgreen),
				frac2cv(mblue), cv_alpha));

	if (color != gx_no_color_index) {
	    color_set_pure(pdc, color);
	    return;
	}
	if ((mred == mgreen && mred == mblue ?	/* gray shade */
	     gx_render_gray_alpha(mred, cv_alpha, pdc, pis, dev, select) :
	     gx_render_rgb_alpha(mred, mgreen, mblue, cv_alpha, pdc, pis, dev, select)) == 1)
	    gx_color_load_select(pdc, pis, dev, select);
    }
}

/* Currently CMYK devices can't handle alpha. */
/* Just multiply the values towards white. */
private void
cmap_rgb_alpha_to_cmyk(frac r, frac g, frac b, frac alpha,
	gx_device_color * pdc, const gs_imager_state * pis, gx_device * dev,
		       gs_color_select_t select)
{
#ifdef PREMULTIPLY_TOWARDS_WHITE
#  undef alpha_bias_value
    frac alpha_bias_value = frac_1 - alpha;

#endif

    cmap_rgb_to_cmyk(alpha_bias((frac) ((long)r * alpha / frac_1)),
		     alpha_bias((frac) ((long)g * alpha / frac_1)),
		     alpha_bias((frac) ((long)b * alpha / frac_1)),
		     pdc, pis, dev, select);
}

#undef alpha_bias
#undef alpha_bias_value

/* ------ Transfer function mapping ------ */

/* Define an identity transfer function. */
float
gs_identity_transfer(floatp value, const gx_transfer_map * pmap)
{
    return value;
}

/* Define the generic transfer function for the library layer. */
/* This just returns what's already in the map. */
float
gs_mapped_transfer(floatp value, const gx_transfer_map * pmap)
{
    return gx_map_color_float(pmap, value);
}

#if FRAC_MAP_INTERPOLATE	/* NOTA BENE */

/* Map a color fraction through a transfer map. */
/* We only use this if we are interpolating. */
frac
gx_color_frac_map(frac cv, const frac * values)
{
#define cp_frac_bits (frac_bits - log2_transfer_map_size)
    int cmi = frac2bits_floor(cv, log2_transfer_map_size);
    frac mv = values[cmi];
    int rem, mdv;

    /* Interpolate between two adjacent values if needed. */
    rem = cv - bits2frac(cmi, log2_transfer_map_size);
    if (rem == 0)
	return mv;
    mdv = values[cmi + 1] - mv;
#if arch_ints_are_short
    /* Only use long multiplication if necessary. */
    if (mdv < -1 << (16 - cp_frac_bits) ||
	mdv > 1 << (16 - cp_frac_bits)
	)
	return mv + (uint) (((ulong) rem * mdv) >> cp_frac_bits);
#endif
    return mv + ((rem * mdv) >> cp_frac_bits);
#undef cp_frac_bits
}

#endif /* FRAC_MAP_INTERPOLATE */

/* ------ Default device color mapping ------ */

/* RGB mapping for black-and-white devices */

/* White-on-black */
gx_color_index
gx_default_w_b_map_rgb_color(gx_device * dev,
		       gx_color_value r, gx_color_value g, gx_color_value b)
{				/* Map values >= 1/2 to 1, < 1/2 to 0. */
    return ((r | g | b) > gx_max_color_value / 2 ?
	    (gx_color_index) 1 : (gx_color_index) 0);
}
int
gx_default_w_b_map_color_rgb(gx_device * dev, gx_color_index color,
			     gx_color_value prgb[3])
{				/* Map 1 to max_value, 0 to 0. */
    prgb[0] = prgb[1] = prgb[2] = -(gx_color_value) color;
    return 0;
}
/* Black-on-white */
gx_color_index
gx_default_b_w_map_rgb_color(gx_device * dev,
		       gx_color_value r, gx_color_value g, gx_color_value b)
{				/* Map values >= 1/2 to 0, < 1/2 to 1. */
    return ((r | g | b) > gx_max_color_value / 2 ?
	    (gx_color_index) 0 : (gx_color_index) 1);
}
int
gx_default_b_w_map_color_rgb(gx_device * dev, gx_color_index color,
			     gx_color_value prgb[3])
{				/* Map 0 to max_value, 1 to 0. */
    prgb[0] = prgb[1] = prgb[2] = -((gx_color_value) color ^ 1);
    return 0;
}

/* RGB mapping for gray-scale devices */

gx_color_index
gx_default_gray_map_rgb_color(gx_device * dev,
		       gx_color_value r, gx_color_value g, gx_color_value b)
{				/* We round the value rather than truncating it. */
    gx_color_value gray =
    (((r * (ulong) lum_red_weight) +
      (g * (ulong) lum_green_weight) +
      (b * (ulong) lum_blue_weight) +
      (lum_all_weights / 2)) / lum_all_weights
     * dev->color_info.max_gray +
     (gx_max_color_value / 2)) / gx_max_color_value;

    return gray;
}

int
gx_default_gray_map_color_rgb(gx_device * dev, gx_color_index color,
			      gx_color_value prgb[3])
{
    gx_color_value gray =
    color * gx_max_color_value / dev->color_info.max_gray;

    prgb[0] = gray;
    prgb[1] = gray;
    prgb[2] = gray;
    return 0;
}

/* RGB mapping for 24-bit true (RGB) color devices */

gx_color_index
gx_default_rgb_map_rgb_color(gx_device * dev,
		       gx_color_value r, gx_color_value g, gx_color_value b)
{
    if (dev->color_info.depth == 24)
	return gx_color_value_to_byte(b) +
	    ((uint) gx_color_value_to_byte(g) << 8) +
	    ((ulong) gx_color_value_to_byte(r) << 16);
    else {
	int bpc = dev->color_info.depth / 3;
	int drop = sizeof(gx_color_value) * 8 - bpc;

	return ((((r >> drop) << bpc) + (g >> drop)) << bpc) + (b >> drop);
    }
}

/* Map a color index to a r-g-b color. */
int
gx_default_rgb_map_color_rgb(gx_device * dev, gx_color_index color,
			     gx_color_value prgb[3])
{
    if (dev->color_info.depth == 24) {
	prgb[0] = gx_color_value_from_byte(color >> 16);
	prgb[1] = gx_color_value_from_byte((color >> 8) & 0xff);
	prgb[2] = gx_color_value_from_byte(color & 0xff);
    } else {
	uint bits_per_color = dev->color_info.depth / 3;
	uint color_mask = (1 << bits_per_color) - 1;

	prgb[0] = ((color >> (bits_per_color * 2)) & color_mask) *
	    (ulong) gx_max_color_value / color_mask;
	prgb[1] = ((color >> (bits_per_color)) & color_mask) *
	    (ulong) gx_max_color_value / color_mask;
	prgb[2] = (color & color_mask) *
	    (ulong) gx_max_color_value / color_mask;
    }
    return 0;
}

/* CMYK mapping for RGB devices (should never be called!) */

gx_color_index
gx_default_map_cmyk_color(gx_device * dev,
     gx_color_value c, gx_color_value m, gx_color_value y, gx_color_value k)
{				/* Convert to RGB */
    frac rgb[3];

    color_cmyk_to_rgb(cv2frac(c), cv2frac(m), cv2frac(y), cv2frac(k),
		      NULL, rgb);
    return gx_map_rgb_color(dev, frac2cv(rgb[0]),
			    frac2cv(rgb[1]), frac2cv(rgb[2]));
}

/* Mapping for CMYK devices */

gx_color_index
cmyk_1bit_map_cmyk_color(gx_device * dev,
			 gx_color_value c, gx_color_value m,
			 gx_color_value y, gx_color_value k)
{
#define CV_BIT(v) ((v) >> (gx_color_value_bits - 1))
    return (gx_color_index)
	(CV_BIT(k) + (CV_BIT(y) << 1) + (CV_BIT(m) << 2) + (CV_BIT(c) << 3));
#undef CV_BIT
}

int
cmyk_1bit_map_color_rgb(gx_device * dev, gx_color_index color,
			gx_color_value prgb[3])
{
    if (color & 1)
	prgb[0] = prgb[1] = prgb[2] = 0;
    else {
	prgb[0] = (color & 8 ? 0 : gx_max_color_value);
	prgb[1] = (color & 4 ? 0 : gx_max_color_value);
	prgb[2] = (color & 2 ? 0 : gx_max_color_value);
    }
    return 0;
}

gx_color_index
cmyk_8bit_map_cmyk_color(gx_device * dev,
			 gx_color_value c, gx_color_value m,
			 gx_color_value y, gx_color_value k)
{
    gx_color_index color =
	gx_color_value_to_byte(k) +
	((uint)gx_color_value_to_byte(y) << 8) +
	((uint)gx_color_value_to_byte(m) << 16) +
	((uint)gx_color_value_to_byte(c) << 24);

    return (color == gx_no_color_index ? color ^ 1 : color);
}

int
cmyk_8bit_map_color_rgb(gx_device * dev, gx_color_index color,
			gx_color_value prgb[3])
{
    int
	not_k = ~color & 0xff,
	r = not_k - (color >> 24),
	g = not_k - ((color >> 16) & 0xff),
	b = not_k - ((color >> 8) & 0xff); 

    prgb[0] = (r < 0 ? 0 : gx_color_value_from_byte(r));
    prgb[1] = (g < 0 ? 0 : gx_color_value_from_byte(g));
    prgb[2] = (b < 0 ? 0 : gx_color_value_from_byte(b));
    return 0;
}

/* Default mapping between RGB+alpha and RGB. */

gx_color_index
gx_default_map_rgb_alpha_color(gx_device * dev,
 gx_color_value r, gx_color_value g, gx_color_value b, gx_color_value alpha)
{				/* Colors have been premultiplied: we don't need to do it here. */
    return gx_map_rgb_color(dev, r, g, b);
}

int
gx_default_map_color_rgb_alpha(gx_device * dev, gx_color_index color,
			       gx_color_value prgba[4])
{
    prgba[3] = gx_max_color_value;	/* alpha = 1 */
    return (*dev_proc(dev, map_color_rgb)) (dev, color, prgba);
}