path: root/gs/src/gdevpsdi.c

/* Copyright (C) 2001-2006 artofcode LLC.
   All Rights Reserved.
  
   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license.  Refer to licensing information at http://www.artifex.com/
   or contact Artifex Software, Inc.,  7 Mt. Lassen Drive - Suite A-134,
   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
*/

/* $Id$ */
/* Image compression for PostScript and PDF writers */
#include "stdio_.h"		/* for jpeglib.h */
#include "jpeglib_.h"		/* for sdct.h */
#include "math_.h"
#include "gx.h"
#include "gserrors.h"
#include "gscspace.h"
#include "gdevpsdf.h"
#include "gdevpsds.h"
#include "gxdevmem.h"
#include "gxcspace.h"
#include "gsparamx.h"
#include "strimpl.h"
#include "scfx.h"
#include "sdct.h"
#include "sjpeg.h"
#include "slzwx.h"
#include "spngpx.h"
#include "srlx.h"
#include "szlibx.h"

/* Define parameter-setting procedures. */
extern stream_state_proc_put_params(s_CF_put_params, stream_CF_state);

/* ---------------- Image compression ---------------- */

/*
 * Add a filter to expand or reduce the pixel width if needed.
 * At least one of bpc_in and bpc_out is 8; the other is 1, 2, 4, or 8,
 * except if bpc_out is 8, bpc_in may be 12.
 */
private int
pixel_resize(psdf_binary_writer * pbw, int width, int num_components,
	     int bpc_in, int bpc_out)
{
    gs_memory_t *mem = pbw->dev->v_memory;
    const stream_template *template;
    stream_1248_state *st;
    int code;

    if (bpc_out == bpc_in)
	return 0;
    if (bpc_in != 8) {
	static const stream_template *const exts[13] = {
	    0, &s_1_8_template, &s_2_8_template, 0, &s_4_8_template,
	    0, 0, 0, 0, 0, 0, 0, &s_12_8_template
	};

	template = exts[bpc_in];
    } else {
	static const stream_template *const rets[5] = {
	    0, &s_8_1_template, &s_8_2_template, 0, &s_8_4_template
	};

	template = rets[bpc_out];
    }
    st = (stream_1248_state *)
	s_alloc_state(mem, template->stype, "pixel_resize state");
    if (st == 0)
	return_error(gs_error_VMerror);
    code = psdf_encode_binary(pbw, template, (stream_state *) st);
    if (code < 0) {
	gs_free_object(mem, st, "pixel_resize state");
	return code;
    }
    s_1248_init(st, width, num_components);
    return 0;
}

private int
convert_color(gx_device *pdev, const gs_color_space *pcs, const gs_imager_state * pis, 
	      gs_client_color *cc, float c[3])
{
    int code;
    gx_device_color dc;

    cs_restrict_color(cc, pcs);
    code = pcs->type->remap_color(cc, pcs, &dc, pis, pdev, gs_color_select_texture);
    if (code < 0)
	return code;
    c[0] = (float)((int)(dc.colors.pure >> pdev->color_info.comp_shift[0]) & ((1 << pdev->color_info.comp_bits[0]) - 1));
    c[1] = (float)((int)(dc.colors.pure >> pdev->color_info.comp_shift[1]) & ((1 << pdev->color_info.comp_bits[1]) - 1));
    c[2] = (float)((int)(dc.colors.pure >> pdev->color_info.comp_shift[2]) & ((1 << pdev->color_info.comp_bits[2]) - 1));
    return 0;
}

/* A hewristic choice of DCT compression parameters - see bug 687174. */
private int 
choose_DCT_params(gx_device *pdev, const gs_color_space *pcs, 
		  const gs_imager_state * pis, 
		  gs_c_param_list *list, gs_c_param_list **param, 
		  stream_state *st) 
{   
    gx_device_memory mdev;
    gs_client_color cc;
    int code;
    float c[4][3];
    const float MIN_FLOAT = - MAX_FLOAT;
    const float domination = (float)0.25;
    const int one = 1, zero = 0;

    if (pcs->type->num_components(pcs) != 3)
	return 0;
    /* Make a copy of the parameter list since we will modify it. */
    code = param_list_copy((gs_param_list *)list, (gs_param_list *)*param);
    if (code < 0)
	return code;
    *param = list;

    /* Create a local memory device for transforming colors to DeviceRGB. */
    gs_make_mem_device(&mdev, gdev_mem_device_for_bits(24), pdev->memory, 0, NULL);
    gx_device_retain((gx_device *)&mdev, true);	/* prevent freeing */
    set_linear_color_bits_mask_shift((gx_device *)&mdev);
    mdev.color_info.separable_and_linear = GX_CINFO_SEP_LIN;

    /* Check for an RGB-like color space.  
       To recognize that we make a matrix as it were a linear operator,
       suppress an ununiformity by subtracting the image of {0,0,0},
       and then check for giagonal domination.  */
    cc.paint.values[0] = cc.paint.values[1] = cc.paint.values[2] = MIN_FLOAT;
    convert_color((gx_device *)&mdev, pcs, pis, &cc, c[3]);
    cc.paint.values[0] = MAX_FLOAT; cc.paint.values[1] = MIN_FLOAT; cc.paint.values[2] = MIN_FLOAT;
    convert_color((gx_device *)&mdev, pcs, pis, &cc, c[0]);
    cc.paint.values[0] = MIN_FLOAT; cc.paint.values[1] = MAX_FLOAT; cc.paint.values[2] = MIN_FLOAT;
    convert_color((gx_device *)&mdev, pcs, pis, &cc, c[1]);
    cc.paint.values[0] = MIN_FLOAT; cc.paint.values[1] = MIN_FLOAT; cc.paint.values[2] = MAX_FLOAT;
    convert_color((gx_device *)&mdev, pcs, pis, &cc, c[2]);
    c[0][0] -= c[3][0]; c[0][1] -= c[3][1]; c[0][2] -= c[3][2];
    c[1][0] -= c[3][0]; c[1][1] -= c[3][1]; c[1][2] -= c[3][2];
    c[2][0] -= c[3][0]; c[2][1] -= c[3][1]; c[2][2] -= c[3][2];
    c[0][0] = any_abs(c[0][0]); c[0][1] = any_abs(c[0][1]); c[0][2] = any_abs(c[0][2]);
    c[1][0] = any_abs(c[1][0]); c[1][1] = any_abs(c[1][1]); c[1][2] = any_abs(c[1][2]);
    c[2][0] = any_abs(c[2][0]); c[2][1] = any_abs(c[2][1]); c[2][2] = any_abs(c[2][2]);
    if (c[0][0] * domination > c[0][1] && c[0][0] * domination > c[0][2] &&
	c[1][1] * domination > c[1][0] && c[1][1] * domination > c[1][2] &&
	c[2][2] * domination > c[2][0] && c[2][2] * domination > c[2][1]) {
	/* Yes, it looks like an RGB color space. 
	   Replace ColorTransform with 1. */
	code = param_write_int((gs_param_list *)list, "ColorTransform", &one);
	if (code < 0)
	    return code;
	goto done;
    }

    /* Check for a Lab-like color space.
       Colors {v,0,0} should map to grays. */
    cc.paint.values[0] = MAX_FLOAT; cc.paint.values[1] = cc.paint.values[2] = 0;
    convert_color((gx_device *)&mdev, pcs, pis, &cc, c[0]);
    cc.paint.values[0] /= 2;
    convert_color((gx_device *)&mdev, pcs, pis, &cc, c[1]);
    cc.paint.values[0] /= 2;
    convert_color((gx_device *)&mdev, pcs, pis, &cc, c[2]);
    c[0][1] -= c[0][0]; c[0][2] -= c[0][0];
    c[1][1] -= c[1][0]; c[1][2] -= c[1][0];
    c[2][1] -= c[2][0]; c[2][2] -= c[2][0];
    c[0][1] = any_abs(c[0][1]); c[0][2] = any_abs(c[0][2]);
    c[1][1] = any_abs(c[1][1]); c[1][2] = any_abs(c[1][2]);
    c[2][1] = any_abs(c[2][1]); c[2][2] = any_abs(c[2][2]);
    if (c[0][0] * domination > c[0][1] && c[0][0] * domination > c[0][2] &&
	c[1][0] * domination > c[1][1] && c[1][0] * domination > c[1][2] &&
	c[2][0] * domination > c[2][1] && c[2][0] * domination > c[2][2]) {
	/* Yes, it looks like an Lab color space. 
	   Replace ColorTransform with 0. */
	code = param_write_int((gs_param_list *)list, "ColorTransform", &zero);
	if (code < 0)
	    return code;
    } else {
	/* Unknown color space type.
	   Replace /HSamples [1 1 1 1] /VSamples [1 1 1 1] to avoid quality degradation. */
	gs_param_string a;
	static const byte v[4] = {1, 1, 1, 1};

	a.data = v;
	a.size = 4;
	a.persistent = true;
	code = param_write_string((gs_param_list *)list, "HSamples", &a);
	if (code < 0)
	    return code;
	code = param_write_string((gs_param_list *)list, "VSamples", &a);
	if (code < 0)
	    return code;
    }
done:
    gs_c_param_list_read(list);
    return 0;
}

/* Add the appropriate image compression filter, if any. */
private int
setup_image_compression(psdf_binary_writer *pbw, const psdf_image_params *pdip,
			const gs_pixel_image_t * pim, const gs_imager_state * pis, 
			bool lossless)
{
    gx_device_psdf *pdev = pbw->dev;
    gs_memory_t *mem = pdev->v_memory;
    const stream_template *template = pdip->filter_template;
    const stream_template *orig_template = template;
    const stream_template *lossless_template =
	(pdev->params.UseFlateCompression &&
	 pdev->version >= psdf_version_ll3 ?
	 &s_zlibE_template : &s_LZWE_template);
    const gs_color_space *pcs = pim->ColorSpace; /* null if mask */
    int Colors = (pcs ? gs_color_space_num_components(pcs) : 1);
    bool Indexed =
	(pcs != 0 && 
	 gs_color_space_get_index(pcs) == gs_color_space_index_Indexed);
    gs_c_param_list *dict = pdip->Dict;
    stream_state *st;
    int code;

    if (!pdip->Encode)		/* no compression */
	return 0;
    if (pdip->AutoFilter) {
	/*
	 * Disregard the requested filter.  What we should do at this point
	 * is analyze the image to decide whether to use JPEG encoding
	 * (DCTEncode with ACSDict) or the lossless filter.  However, since
	 * we don't buffer the entire image, we'll make the choice on-fly,
	 * forking the image data into 3 streams : (1) JPEG, (2) lossless,
	 * (3) the compression chooser. In this case this function is
	 * called 2 times with different values of the 'lossless' argument.
	 */
        if (lossless) {
            orig_template = template = lossless_template;
        } else {
            orig_template = template = &s_DCTE_template;
        }
	dict = pdip->ACSDict;
    } else if (!lossless)
	return gs_error_rangecheck; /* Reject the alternative stream. */   
    if (pdev->version < psdf_version_ll3 && template == &s_zlibE_template)
	orig_template = template = lossless_template;
    if (dict) /* NB: rather than dereference NULL lets continue on without a dict */
	gs_c_param_list_read(dict);	/* ensure param list is in read mode */
    if (template == 0)	/* no compression */
	return 0;
    if (pim->Width < 200 && pim->Height < 200) /* Prevent a fixed overflow. */
	if (pim->Width * pim->Height * Colors * pim->BitsPerComponent <= 160)
	    return 0;  /* not worth compressing */
    /* Only use DCTE for 8-bit, non-Indexed data. */
    if (template == &s_DCTE_template) {
	if (Indexed ||
            !(pdip->Downsample ?
	      pdip->Depth == 8 ||
	      (pdip->Depth == -1 && pim->BitsPerComponent == 8) :
	      pim->BitsPerComponent == 8)
	    ) {
	    /* Use LZW/Flate instead. */
	    template = lossless_template;
	}
    }
    st = s_alloc_state(mem, template->stype, "setup_image_compression");
    if (st == 0)
	return_error(gs_error_VMerror);
    if (template->set_defaults)
	(*template->set_defaults) (st);
    if (template == &s_CFE_template) {
	stream_CFE_state *const ss = (stream_CFE_state *) st;

	if (pdip->Dict != 0 && pdip->filter_template == template) {
	    s_CF_put_params((gs_param_list *)pdip->Dict,
			    (stream_CF_state *)ss); /* ignore errors */
	} else {
	    ss->K = -1;
	    ss->BlackIs1 = true;
	}
	ss->Columns = pim->Width;
	ss->Rows = (ss->EndOfBlock ? 0 : pim->Height);
    } else if ((template == &s_LZWE_template ||
		template == &s_zlibE_template) &&
	       pdev->version >= psdf_version_ll3) {
	/* If not Indexed, add a PNGPredictor filter. */
	if (!Indexed) {
	    code = psdf_encode_binary(pbw, template, st);
	    if (code < 0)
		goto fail;
	    template = &s_PNGPE_template;
	    st = s_alloc_state(mem, template->stype, "setup_image_compression");
	    if (st == 0) {
		code = gs_note_error(gs_error_VMerror);
		goto fail;
	    }
	    if (template->set_defaults)
		(*template->set_defaults) (st);
	    {
		stream_PNGP_state *const ss = (stream_PNGP_state *) st;

		ss->Colors = Colors;
		ss->Columns = pim->Width;
	    }
	}
    } else if (template == &s_DCTE_template) {
	gs_c_param_list list, *param = dict;

	gs_c_param_list_write(&list, mem);
	code = choose_DCT_params((gx_device *)pbw->dev, pcs, pis, &list, &param, st);
	if (code < 0) {
    	    gs_c_param_list_release(&list);
	    return code;
	}
	code = psdf_DCT_filter((gs_param_list *)param,
			       st, pim->Width, pim->Height, Colors, pbw);
	gs_c_param_list_release(&list);
	if (code < 0)
	    goto fail;
	/* psdf_DCT_filter already did the psdf_encode_binary. */
	return 0;
    } else if (template == &s_LZWE_template) {
	if (template->set_defaults)
	    (*template->set_defaults) (st);
    }
    code = psdf_encode_binary(pbw, template, st);
    if (code >= 0)
	return 0;
 fail:
    gs_free_object(mem, st, "setup_image_compression");
    return code;
}

/* Determine whether an image should be downsampled. */
private bool
do_downsample(const psdf_image_params *pdip, const gs_pixel_image_t *pim,
	      floatp resolution)
{
    floatp factor = (int)(resolution / pdip->Resolution);

    return (pdip->Downsample && factor >= pdip->DownsampleThreshold &&
	    factor <= pim->Width && factor <= pim->Height);
}

/* Add downsampling, antialiasing, and compression filters. */
/* Uses AntiAlias, Depth, DownsampleThreshold, DownsampleType, Resolution. */
/* Assumes do_downsampling() is true. */
private int
setup_downsampling(psdf_binary_writer * pbw, const psdf_image_params * pdip,
		   gs_pixel_image_t * pim, const gs_imager_state * pis, 
		   floatp resolution, bool lossless)
{
    gx_device_psdf *pdev = pbw->dev;
    /* Note: Bicubic is currently interpreted as Average. */
    const stream_template *template =
	(pdip->DownsampleType == ds_Subsample ?
	 &s_Subsample_template : &s_Average_template);
    int factor = (int)(resolution / pdip->Resolution);
    int orig_bpc = pim->BitsPerComponent;
    int orig_width = pim->Width;
    int orig_height = pim->Height;
    stream_state *st;
    int code;

    st = s_alloc_state(pdev->v_memory, template->stype,
		       "setup_downsampling");
    if (st == 0)
	return_error(gs_error_VMerror);
    if (template->set_defaults)
	template->set_defaults(st);
    {
	stream_Downsample_state *const ss = (stream_Downsample_state *) st;

	ss->Colors =
	    (pim->ColorSpace == 0 ? 1 /*mask*/ :
	     gs_color_space_num_components(pim->ColorSpace));
	ss->WidthIn = pim->Width;
	ss->HeightIn = pim->Height;
	ss->XFactor = ss->YFactor = factor;
	ss->AntiAlias = pdip->AntiAlias;
	ss->padX = ss->padY = false; /* should be true */
	if (template->init)
	    template->init(st);
	pim->Width = s_Downsample_size_out(pim->Width, factor, ss->padX);
	pim->Height = s_Downsample_size_out(pim->Height, factor, ss->padY);
	pim->BitsPerComponent = pdip->Depth;
	gs_matrix_scale(&pim->ImageMatrix, (double)pim->Width / orig_width,
			(double)pim->Height / orig_height,
			&pim->ImageMatrix);
	/****** NO ANTI-ALIASING YET ******/
	if ((code = setup_image_compression(pbw, pdip, pim, pis, lossless)) < 0 ||
	    (code = pixel_resize(pbw, pim->Width, ss->Colors,
				 8, pdip->Depth)) < 0 ||
	    (code = psdf_encode_binary(pbw, template, st)) < 0 ||
	    (code = pixel_resize(pbw, orig_width, ss->Colors,
				 orig_bpc, 8)) < 0
	    ) {
	    gs_free_object(pdev->v_memory, st, "setup_image_compression");
	    return code;
	}
    }
    return 0;
}

/* Decive whether to convert an image to RGB. */
bool
psdf_is_converting_image_to_RGB(const gx_device_psdf * pdev, 
		const gs_imager_state * pis, const gs_pixel_image_t * pim)
{
    return pdev->params.ConvertCMYKImagesToRGB &&
	    pis != 0 &&
	    gs_color_space_get_index(pim->ColorSpace) ==
	    gs_color_space_index_DeviceCMYK;
}

/* Set up compression and downsampling filters for an image. */
/* Note that this may modify the image parameters. */
int
psdf_setup_image_filters(gx_device_psdf * pdev, psdf_binary_writer * pbw,
			 gs_pixel_image_t * pim, const gs_matrix * pctm,
			 const gs_imager_state * pis, bool lossless)
{
    /*
     * The following algorithms are per Adobe Tech Note # 5151,
     * "Acrobat Distiller Parameters", revised 16 September 1996
     * for Acrobat(TM) Distiller(TM) 3.0.
     *
     * The control structure is a little tricky, because filter
     * pipelines must be constructed back-to-front.
     */
    int code = 0;
    psdf_image_params params;
    int bpc = pim->BitsPerComponent;
    int bpc_out = pim->BitsPerComponent = min(bpc, 8);
    int ncomp;
    double resolution;

    /*
     * The Adobe documentation doesn't say this, but mask images are
     * compressed on the same basis as 1-bit-deep monochrome images,
     * except that anti-aliasing (resolution/depth tradeoff) is not
     * allowed.
     */
    if (pim->ColorSpace == NULL) { /* mask image */
	params = pdev->params.MonoImage;
	params.Depth = 1;
	ncomp = 1;
    } else {
	ncomp = gs_color_space_num_components(pim->ColorSpace);
	if (ncomp == 1) {
	    if (bpc == 1)
		params = pdev->params.MonoImage;
	    else
		params = pdev->params.GrayImage;
	    if (params.Depth == -1)
		params.Depth = bpc;
	} else {
	    params = pdev->params.ColorImage;
	    /* params.Depth is reset below */
	}
    }

    /*
     * We can compute the image resolution by:
     *    W / (W * ImageMatrix^-1 * CTM / HWResolution).
     * We can replace W by 1 to simplify the computation.
     */
    if (pctm == 0)
	resolution = -1;
    else {
	gs_point pt;

	/* We could do both X and Y, but why bother? */
	code = gs_distance_transform_inverse(1.0, 0.0, &pim->ImageMatrix, &pt);
	if (code < 0)
	    return code;
	gs_distance_transform(pt.x, pt.y, pctm, &pt);
	resolution = 1.0 / hypot(pt.x / pdev->HWResolution[0],
				 pt.y / pdev->HWResolution[1]);
    }
    if (ncomp == 1) {
	/* Monochrome, gray, or mask */
	/* Check for downsampling. */
	if (do_downsample(&params, pim, resolution)) {
	    /* Use the downsampled depth, not the original data depth. */
	    if (params.Depth == 1) {
		params.Filter = pdev->params.MonoImage.Filter;
		params.filter_template = pdev->params.MonoImage.filter_template;
		params.Dict = pdev->params.MonoImage.Dict;
	    } else {
		params.Filter = pdev->params.GrayImage.Filter;
		params.filter_template = pdev->params.GrayImage.filter_template;
		params.Dict = pdev->params.GrayImage.Dict;
	    }
	    code = setup_downsampling(pbw, &params, pim, pis, resolution, lossless);
	} else {
	    code = setup_image_compression(pbw, &params, pim, pis, lossless);
	}
	if (code < 0)
	    return code;
	code = pixel_resize(pbw, pim->Width, ncomp, bpc, bpc_out);
    } else {
	/* Color */
	bool cmyk_to_rgb = psdf_is_converting_image_to_RGB(pdev, pis, pim);

	if (cmyk_to_rgb) {
	    extern_st(st_color_space);
	    gs_memory_t *mem = pdev->v_memory;
	    gs_color_space *rgb_cs = gs_alloc_struct(mem, 
		    gs_color_space, &st_color_space, "psdf_setup_image_filters");

	    gs_cspace_init_DeviceRGB(mem, rgb_cs);  /* idempotent initialization */
	    pim->ColorSpace = rgb_cs;
	}
	if (params.Depth == -1)
	    params.Depth = (cmyk_to_rgb ? 8 : bpc_out);
	if (do_downsample(&params, pim, resolution)) {
	    code = setup_downsampling(pbw, &params, pim, pis, resolution, lossless);
	} else {
	    code = setup_image_compression(pbw, &params, pim, pis, lossless);
	}
	if (code < 0)
	    return code;
	if (cmyk_to_rgb) {
	    gs_memory_t *mem = pdev->v_memory;
	    stream_C2R_state *ss = (stream_C2R_state *)
		s_alloc_state(mem, s_C2R_template.stype, "C2R state");
	    int code = pixel_resize(pbw, pim->Width, 3, 8, bpc_out);
		    
	    if (code < 0 ||
		(code = psdf_encode_binary(pbw, &s_C2R_template,
					   (stream_state *) ss)) < 0 ||
		(code = pixel_resize(pbw, pim->Width, 4, bpc, 8)) < 0
		)
		return code;
	    s_C2R_init(ss, pis);
	} else {
	    code = pixel_resize(pbw, pim->Width, ncomp, bpc, bpc_out);
	    if (code < 0)
		return code;
	}
    }
    return code;
}

/* Set up compression filters for a lossless image, with no downsampling, */
/* no color space conversion, and only lossless filters. */
/* Note that this may modify the image parameters. */
int
psdf_setup_lossless_filters(gx_device_psdf *pdev, psdf_binary_writer *pbw,
			    gs_pixel_image_t *pim)
{
    /*
     * Set up a device with modified parameters for computing the image
     * compression filters.  Don't allow downsampling or lossy compression.
     */
    gx_device_psdf ipdev;

    ipdev = *pdev;
    ipdev.params.ColorImage.AutoFilter = false;
    ipdev.params.ColorImage.Downsample = false;
    ipdev.params.ColorImage.Filter = "FlateEncode";
    ipdev.params.ColorImage.filter_template = &s_zlibE_template;
    ipdev.params.ConvertCMYKImagesToRGB = false;
    ipdev.params.GrayImage.AutoFilter = false;
    ipdev.params.GrayImage.Downsample = false;
    ipdev.params.GrayImage.Filter = "FlateEncode";
    ipdev.params.GrayImage.filter_template = &s_zlibE_template;
    return psdf_setup_image_filters(&ipdev, pbw, pim, NULL, NULL, true);
}

/* Set up image compression chooser. */
int
psdf_setup_compression_chooser(psdf_binary_writer *pbw, gx_device_psdf *pdev,
		    int width, int height, int depth, int bits_per_sample)
{
    int code;
    stream_state *ss = s_alloc_state(pdev->memory, s_compr_chooser_template.stype, 
                                     "psdf_setup_compression_chooser");

    if (ss == 0)
	return_error(gs_error_VMerror);
    pbw->memory = pdev->memory;
    pbw->strm = pdev->strm; /* just a stub - will not write to it. */
    pbw->dev = pdev;
    pbw->target = pbw->strm; /* Since s_add_filter may insert NullEncode to comply buffering,
			         will need to close a chain of filetrs. */
    code = psdf_encode_binary(pbw, &s_compr_chooser_template, ss);
    if (code < 0)
	return code;
    code = s_compr_chooser_set_dimensions((stream_compr_chooser_state *)ss, 
		    width, height, depth, bits_per_sample);
    return code;
}

/* Set up an "image to mask" filter. */
int
psdf_setup_image_to_mask_filter(psdf_binary_writer *pbw, gx_device_psdf *pdev,
		    int width, int height, int depth, int bits_per_sample, uint *MaskColor)
{
    int code;
    stream_state *ss = s_alloc_state(pdev->memory, s__image_colors_template.stype, 
	"psdf_setup_image_colors_filter");

    if (ss == 0)
	return_error(gs_error_VMerror);
    pbw->memory = pdev->memory;
    pbw->dev = pdev;
    code = psdf_encode_binary(pbw, &s__image_colors_template, ss);
    if (code < 0)
	return code;
    s_image_colors_set_dimensions((stream_image_colors_state *)ss, 
		    width, height, depth, bits_per_sample);
    s_image_colors_set_mask_colors((stream_image_colors_state *)ss, MaskColor);
    return 0;
}

/* Set up an image colors filter. */
int
psdf_setup_image_colors_filter(psdf_binary_writer *pbw, 
			       gx_device_psdf *pdev, gs_pixel_image_t * pim, 
			       const gs_imager_state *pis)
{   /* fixme: currently it's a stub convertion to mask. */
    int code;
    stream_state *ss = s_alloc_state(pdev->memory, s__image_colors_template.stype, 
	"psdf_setup_image_colors_filter");
    int i;

    if (ss == 0)
	return_error(gs_error_VMerror);
    pbw->memory = pdev->memory;
    pbw->dev = pdev;
    code = psdf_encode_binary(pbw, &s__image_colors_template, ss);
    if (code < 0)
	return code;
    s_image_colors_set_dimensions((stream_image_colors_state *)ss, 
		    pim->Width, pim->Height, 
		    gs_color_space_num_components(pim->ColorSpace), 
		    pim->BitsPerComponent);
    s_image_colors_set_color_space((stream_image_colors_state *)ss, 
		    (gx_device *)pdev, pim->ColorSpace, pis, pim->Decode);
    pim->BitsPerComponent = pdev->color_info.comp_bits[0]; /* Same precision for all components. */
    for (i = 0; i < pdev->color_info.num_components; i++) {
	pim->Decode[i * 2 + 0] = 0;
	pim->Decode[i * 2 + 1] = 1;
    }
    return 0;
}