/*

* jdmerge.c

*

* Copyright (C) 1994-1996, Thomas G. Lane.

* This file is part of the Independent JPEG Group's software.

* For conditions of distribution and use, see the accompanying README file.

*

* This file contains code for merged upsampling/color conversion.

*

* This file combines functions from jdsample.c and jdcolor.c;

* read those files first to understand what's going on.

*

* When the chroma components are to be upsampled by simple replication

* (ie, box filtering), we can save some work in color conversion by

* calculating all the output pixels corresponding to a pair of chroma

* samples at one time. In the conversion equations

* R = Y + K1 * Cr

* G = Y + K2 * Cb + K3 * Cr

* B = Y + K4 * Cb

* only the Y term varies among the group of pixels corresponding to a pair

* of chroma samples, so the rest of the terms can be calculated just once.

* At typical sampling ratios, this eliminates half or three-quarters of the

* multiplications needed for color conversion.

*

* This file currently provides implementations for the following cases:

* YCC => RGB color conversion only (YCbCr or BG_YCC).

* Sampling ratios of 2h1v or 2h2v.

* No scaling needed at upsample time.

* Corner-aligned (non-CCIR601) sampling alignment.

* Other special cases could be added, but in most applications these are

* the only common cases. (For uncommon cases we fall back on the more

* general code in jdsample.c and jdcolor.c.)

*/

#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"

#ifdef UPSAMPLE_MERGING_SUPPORTED

#if RANGE_BITS < 2

/* Deliberate syntax err */

Sorry, this code requires 2 or more range extension bits.

#endif

/* Private subobject */

typedef struct {

struct jpeg_upsampler pub; /* public fields */

/* Pointer to routine to do actual upsampling/conversion of one row group */

JMETHOD(void, upmethod, (j_decompress_ptr cinfo,

JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,

JSAMPARRAY output_buf));

/* Private state for YCC->RGB conversion */

int * Cr_r_tab; /* => table for Cr to R conversion */

int * Cb_b_tab; /* => table for Cb to B conversion */

INT32 * Cr_g_tab; /* => table for Cr to G conversion */

INT32 * Cb_g_tab; /* => table for Cb to G conversion */

/* For 2:1 vertical sampling, we produce two output rows at a time.

* We need a "spare" row buffer to hold the second output row if the

* application provides just a one-row buffer; we also use the spare

* to discard the dummy last row if the image height is odd.

*/

JSAMPROW spare_row;

boolean spare_full; /* T if spare buffer is occupied */

JDIMENSION out_row_width; /* samples per output row */

JDIMENSION rows_to_go; /* counts rows remaining in image */

} my_upsampler;

typedef my_upsampler * my_upsample_ptr;

#define SCALEBITS 16 /* speediest right-shift on some machines */

#define ONE_HALF ((INT32) 1 << (SCALEBITS-1))

#define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))

/*

* Initialize tables for YCbCr->RGB and BG_YCC->RGB colorspace conversion.

* This is taken directly from jdcolor.c; see that file for more info.

*/

LOCAL(void)

build_ycc_rgb_table (j_decompress_ptr cinfo)

/* Normal case, sYCC */

{

my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

int i;

INT32 x;

SHIFT_TEMPS

upsample->Cr_r_tab = (int *) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));

upsample->Cb_b_tab = (int *) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));

upsample->Cr_g_tab = (INT32 *) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));

upsample->Cb_g_tab = (INT32 *) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));

for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {

/* i is the actual input pixel value, in the range 0..MAXJSAMPLE */

/* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */

/* Cr=>R value is nearest int to 1.402 * x */

/* Cr=>G value is scaled-up -0.714136286 * x */

upsample->Cr_g_tab[i] = (- FIX(0.714136286)) * x;

/* Cb=>G value is scaled-up -0.344136286 * x */

/* We also add in ONE_HALF so that need not do it in inner loop */

upsample->Cb_g_tab[i] = (- FIX(0.344136286)) * x + ONE_HALF;

}

}

LOCAL(void)

build_bg_ycc_rgb_table (j_decompress_ptr cinfo)

/* Wide gamut case, bg-sYCC */

{

my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

int i;

INT32 x;

SHIFT_TEMPS

upsample->Cr_r_tab = (int *) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));

upsample->Cb_b_tab = (int *) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(int));

upsample->Cr_g_tab = (INT32 *) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));

upsample->Cb_g_tab = (INT32 *) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE+1) * SIZEOF(INT32));

for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {

/* i is the actual input pixel value, in the range 0..MAXJSAMPLE */

/* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */

/* Cr=>R value is nearest int to 2.804 * x */

/* Cr=>G value is scaled-up -1.428272572 * x */

upsample->Cr_g_tab[i] = (- FIX(1.428272572)) * x;

/* Cb=>G value is scaled-up -0.688272572 * x */

/* We also add in ONE_HALF so that need not do it in inner loop */

upsample->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF;

}

}

/*

* Initialize for an upsampling pass.

*/

METHODDEF(void)

start_pass_merged_upsample (j_decompress_ptr cinfo)

{

my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

/* Mark the spare buffer empty */

upsample->spare_full = FALSE;

/* Initialize total-height counter for detecting bottom of image */

upsample->rows_to_go = cinfo->output_height;

}

/*

* Control routine to do upsampling (and color conversion).

*

* The control routine just handles the row buffering considerations.

*/

METHODDEF(void)

merged_2v_upsample (j_decompress_ptr cinfo,

JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

JDIMENSION in_row_groups_avail,

JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

JDIMENSION out_rows_avail)

/* 2:1 vertical sampling case: may need a spare row. */

{

my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

JSAMPROW work_ptrs[2];

JDIMENSION num_rows; /* number of rows returned to caller */

if (upsample->spare_full) {

/* If we have a spare row saved from a previous cycle, just return it. */

jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,

1, upsample->out_row_width);

num_rows = 1;

upsample->spare_full = FALSE;

} else {

/* Figure number of rows to return to caller. */

num_rows = 2;

/* Not more than the distance to the end of the image. */

if (num_rows > upsample->rows_to_go)

num_rows = upsample->rows_to_go;

/* And not more than what the client can accept: */

out_rows_avail -= *out_row_ctr;

if (num_rows > out_rows_avail)

num_rows = out_rows_avail;

/* Create output pointer array for upsampler. */

work_ptrs[0] = output_buf[*out_row_ctr];

if (num_rows > 1) {

work_ptrs[1] = output_buf[*out_row_ctr + 1];

} else {

work_ptrs[1] = upsample->spare_row;

upsample->spare_full = TRUE;

}

/* Now do the upsampling. */

(*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs);

}

/* Adjust counts */

*out_row_ctr += num_rows;

upsample->rows_to_go -= num_rows;

/* When the buffer is emptied, declare this input row group consumed */

if (! upsample->spare_full)

(*in_row_group_ctr)++;

}

METHODDEF(void)

merged_1v_upsample (j_decompress_ptr cinfo,

JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

JDIMENSION in_row_groups_avail,

JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

JDIMENSION out_rows_avail)

/* 1:1 vertical sampling case: much easier, never need a spare row. */

{

my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

/* Just do the upsampling. */

(*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr,

output_buf + *out_row_ctr);

/* Adjust counts */

(*out_row_ctr)++;

(*in_row_group_ctr)++;

}

/*

* These are the routines invoked by the control routines to do

* the actual upsampling/conversion. One row group is processed per call.

*

* Note: since we may be writing directly into application-supplied buffers,

* we have to be honest about the output width; we can't assume the buffer

* has been rounded up to an even width.

*/

/*

* Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.

*/

METHODDEF(void)

h2v1_merged_upsample (j_decompress_ptr cinfo,

JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,

JSAMPARRAY output_buf)

{

my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

register int y, cred, cgreen, cblue;

int cb, cr;

register JSAMPROW outptr;

JSAMPROW inptr0, inptr1, inptr2;

JDIMENSION col;

/* copy these pointers into registers if possible */

register JSAMPLE * range_limit = cinfo->sample_range_limit;

int * Crrtab = upsample->Cr_r_tab;

int * Cbbtab = upsample->Cb_b_tab;

INT32 * Crgtab = upsample->Cr_g_tab;

INT32 * Cbgtab = upsample->Cb_g_tab;

SHIFT_TEMPS

inptr0 = input_buf[0][in_row_group_ctr];

inptr1 = input_buf[1][in_row_group_ctr];

inptr2 = input_buf[2][in_row_group_ctr];

outptr = output_buf[0];

/* Loop for each pair of output pixels */

for (col = cinfo->output_width >> 1; col > 0; col--) {

/* Do the chroma part of the calculation */

cb = GETJSAMPLE(*inptr1++);

cr = GETJSAMPLE(*inptr2++);

cred = Crrtab[cr];

cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);

cblue = Cbbtab[cb];

/* Fetch 2 Y values and emit 2 pixels */

y = GETJSAMPLE(*inptr0++);

outptr[RGB_RED] = range_limit[y + cred];

outptr[RGB_GREEN] = range_limit[y + cgreen];

outptr[RGB_BLUE] = range_limit[y + cblue];

outptr += RGB_PIXELSIZE;

y = GETJSAMPLE(*inptr0++);

outptr[RGB_RED] = range_limit[y + cred];

outptr[RGB_GREEN] = range_limit[y + cgreen];

outptr[RGB_BLUE] = range_limit[y + cblue];

outptr += RGB_PIXELSIZE;

}

/* If image width is odd, do the last output column separately */

if (cinfo->output_width & 1) {

cb = GETJSAMPLE(*inptr1);

cr = GETJSAMPLE(*inptr2);

cred = Crrtab[cr];

cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);

cblue = Cbbtab[cb];

y = GETJSAMPLE(*inptr0);

outptr[RGB_RED] = range_limit[y + cred];

outptr[RGB_GREEN] = range_limit[y + cgreen];

outptr[RGB_BLUE] = range_limit[y + cblue];

}

}

/*

* Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.

*/

METHODDEF(void)

h2v2_merged_upsample (j_decompress_ptr cinfo,

JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,

JSAMPARRAY output_buf)

{

my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

register int y, cred, cgreen, cblue;

int cb, cr;

register JSAMPROW outptr0, outptr1;

JSAMPROW inptr00, inptr01, inptr1, inptr2;

JDIMENSION col;

/* copy these pointers into registers if possible */

register JSAMPLE * range_limit = cinfo->sample_range_limit;

int * Crrtab = upsample->Cr_r_tab;

int * Cbbtab = upsample->Cb_b_tab;

INT32 * Crgtab = upsample->Cr_g_tab;

INT32 * Cbgtab = upsample->Cb_g_tab;

SHIFT_TEMPS

inptr00 = input_buf[0][in_row_group_ctr*2];

inptr01 = input_buf[0][in_row_group_ctr*2 + 1];

inptr1 = input_buf[1][in_row_group_ctr];

inptr2 = input_buf[2][in_row_group_ctr];

outptr0 = output_buf[0];

outptr1 = output_buf[1];

/* Loop for each group of output pixels */

for (col = cinfo->output_width >> 1; col > 0; col--) {

/* Do the chroma part of the calculation */

cb = GETJSAMPLE(*inptr1++);

cr = GETJSAMPLE(*inptr2++);

cred = Crrtab[cr];

cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);

cblue = Cbbtab[cb];

/* Fetch 4 Y values and emit 4 pixels */

y = GETJSAMPLE(*inptr00++);

outptr0[RGB_RED] = range_limit[y + cred];

outptr0[RGB_GREEN] = range_limit[y + cgreen];

outptr0[RGB_BLUE] = range_limit[y + cblue];

outptr0 += RGB_PIXELSIZE;

y = GETJSAMPLE(*inptr00++);

outptr0[RGB_RED] = range_limit[y + cred];

outptr0[RGB_GREEN] = range_limit[y + cgreen];

outptr0[RGB_BLUE] = range_limit[y + cblue];

outptr0 += RGB_PIXELSIZE;

y = GETJSAMPLE(*inptr01++);

outptr1[RGB_RED] = range_limit[y + cred];

outptr1[RGB_GREEN] = range_limit[y + cgreen];

outptr1[RGB_BLUE] = range_limit[y + cblue];

outptr1 += RGB_PIXELSIZE;

y = GETJSAMPLE(*inptr01++);

outptr1[RGB_RED] = range_limit[y + cred];

outptr1[RGB_GREEN] = range_limit[y + cgreen];

outptr1[RGB_BLUE] = range_limit[y + cblue];

outptr1 += RGB_PIXELSIZE;

}

/* If image width is odd, do the last output column separately */

if (cinfo->output_width & 1) {

cb = GETJSAMPLE(*inptr1);

cr = GETJSAMPLE(*inptr2);

cred = Crrtab[cr];

cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);

cblue = Cbbtab[cb];

y = GETJSAMPLE(*inptr00);

outptr0[RGB_RED] = range_limit[y + cred];

outptr0[RGB_GREEN] = range_limit[y + cgreen];

outptr0[RGB_BLUE] = range_limit[y + cblue];

y = GETJSAMPLE(*inptr01);

outptr1[RGB_RED] = range_limit[y + cred];

outptr1[RGB_GREEN] = range_limit[y + cgreen];

outptr1[RGB_BLUE] = range_limit[y + cblue];

}

}

/*

* Module initialization routine for merged upsampling/color conversion.

*

* NB: this is called under the conditions determined by use_merged_upsample()

* in jdmaster.c. That routine MUST correspond to the actual capabilities

* of this module; no safety checks are made here.

*/

GLOBAL(void)

jinit_merged_upsampler (j_decompress_ptr cinfo)

{

my_upsample_ptr upsample;

upsample = (my_upsample_ptr) (*cinfo->mem->alloc_small)

((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_upsampler));

cinfo->upsample = &upsample->pub;

upsample->pub.start_pass = start_pass_merged_upsample;

upsample->pub.need_context_rows = FALSE;

upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;

if (cinfo->max_v_samp_factor == 2) {

upsample->pub.upsample = merged_2v_upsample;

upsample->upmethod = h2v2_merged_upsample;

/* Allocate a spare row buffer */

upsample->spare_row = (JSAMPROW) (*cinfo->mem->alloc_large)

((j_common_ptr) cinfo, JPOOL_IMAGE,

(size_t) upsample->out_row_width * SIZEOF(JSAMPLE));

} else {

upsample->pub.upsample = merged_1v_upsample;

upsample->upmethod = h2v1_merged_upsample;

/* No spare row needed */

upsample->spare_row = NULL;

}

if (cinfo->jpeg_color_space == JCS_BG_YCC)

build_bg_ycc_rgb_table(cinfo);

else

build_ycc_rgb_table(cinfo);

}

#endif /* UPSAMPLE_MERGING_SUPPORTED */