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/*
* jdsample.c
*
* Copyright (C) 1991, 1992, 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 un-subsampling routines.
* These routines are invoked via the unsubsample and
* unsubsample_init/term methods.
*/
#include "jinclude.h"
/*
* Initialize for un-subsampling a scan.
*/
METHODDEF void
unsubsample_init (decompress_info_ptr cinfo)
{
/* no work for now */
}
/*
* Un-subsample pixel values of a single component.
* This version handles any integral sampling ratios.
* This is not used for typical JPEG files, so it need not be fast.
*/
METHODDEF void
int_unsubsample (decompress_info_ptr cinfo, int which_component,
long input_cols, int input_rows,
long output_cols, int output_rows,
JSAMPARRAY above, JSAMPARRAY input_data, JSAMPARRAY below,
JSAMPARRAY output_data)
{
jpeg_component_info * compptr = cinfo->cur_comp_info[which_component];
register JSAMPROW inptr, outptr;
register JSAMPLE invalue;
register short h_expand, h;
short v_expand, v;
int inrow, outrow;
register long incol;
#ifdef DEBUG /* for debugging pipeline controller */
if (input_rows != compptr->v_samp_factor ||
output_rows != cinfo->max_v_samp_factor ||
(input_cols % compptr->h_samp_factor) != 0 ||
(output_cols % cinfo->max_h_samp_factor) != 0 ||
output_cols*compptr->h_samp_factor != input_cols*cinfo->max_h_samp_factor)
ERREXIT(cinfo->emethods, "Bogus unsubsample parameters");
#endif
h_expand = cinfo->max_h_samp_factor / compptr->h_samp_factor;
v_expand = cinfo->max_v_samp_factor / compptr->v_samp_factor;
outrow = 0;
for (inrow = 0; inrow < input_rows; inrow++) {
for (v = 0; v < v_expand; v++) {
inptr = input_data[inrow];
outptr = output_data[outrow++];
for (incol = 0; incol < input_cols; incol++) {
invalue = GETJSAMPLE(*inptr++);
for (h = 0; h < h_expand; h++) {
*outptr++ = invalue;
}
}
}
}
}
/*
* Un-subsample pixel values of a single component.
* This version handles the extremely common case of
* horizontal expansion by 2 and any integral vertical expansion.
*/
METHODDEF void
h2_unsubsample (decompress_info_ptr cinfo, int which_component,
long input_cols, int input_rows,
long output_cols, int output_rows,
JSAMPARRAY above, JSAMPARRAY input_data, JSAMPARRAY below,
JSAMPARRAY output_data)
{
jpeg_component_info * compptr = cinfo->cur_comp_info[which_component];
register JSAMPROW inptr, outptr;
register JSAMPLE invalue;
short v_expand, v;
int inrow, outrow;
register long incol;
#ifdef DEBUG /* for debugging pipeline controller */
if (input_rows != compptr->v_samp_factor ||
output_rows != cinfo->max_v_samp_factor ||
(input_cols % compptr->h_samp_factor) != 0 ||
(output_cols % cinfo->max_h_samp_factor) != 0 ||
output_cols*compptr->h_samp_factor != input_cols*cinfo->max_h_samp_factor)
ERREXIT(cinfo->emethods, "Bogus unsubsample parameters");
#endif
v_expand = cinfo->max_v_samp_factor / compptr->v_samp_factor;
/* The subsampled image width will always be a multiple of DCTSIZE,
* so we can unroll the inner loop.
*/
outrow = 0;
for (inrow = 0; inrow < input_rows; inrow++) {
for (v = 0; v < v_expand; v++) {
inptr = input_data[inrow];
outptr = output_data[outrow++];
#if DCTSIZE == 8
for (incol = 0; incol < input_cols; incol += DCTSIZE) {
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
}
#else /* nonstandard DCTSIZE */
for (incol = 0; incol < input_cols; incol++) {
invalue = GETJSAMPLE(*inptr++);
*outptr++ = invalue;
*outptr++ = invalue;
}
#endif
}
}
}
/*
* Un-subsample pixel values of a single component.
* This version handles the special case of a full-size component.
*/
METHODDEF void
fullsize_unsubsample (decompress_info_ptr cinfo, int which_component,
long input_cols, int input_rows,
long output_cols, int output_rows,
JSAMPARRAY above, JSAMPARRAY input_data, JSAMPARRAY below,
JSAMPARRAY output_data)
{
#ifdef DEBUG /* for debugging pipeline controller */
if (input_cols != output_cols || input_rows != output_rows)
ERREXIT(cinfo->emethods, "Pipeline controller messed up");
#endif
jcopy_sample_rows(input_data, 0, output_data, 0, output_rows, output_cols);
}
/*
* Clean up after a scan.
*/
METHODDEF void
unsubsample_term (decompress_info_ptr cinfo)
{
/* no work for now */
}
/*
* The method selection routine for unsubsampling.
* Note that we must select a routine for each component.
*/
GLOBAL void
jselunsubsample (decompress_info_ptr cinfo)
{
short ci;
jpeg_component_info * compptr;
if (cinfo->CCIR601_sampling)
ERREXIT(cinfo->emethods, "CCIR601 subsampling not implemented yet");
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
if (compptr->h_samp_factor == cinfo->max_h_samp_factor &&
compptr->v_samp_factor == cinfo->max_v_samp_factor)
cinfo->methods->unsubsample[ci] = fullsize_unsubsample;
else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor &&
(cinfo->max_v_samp_factor % compptr->v_samp_factor) == 0)
cinfo->methods->unsubsample[ci] = h2_unsubsample;
else if ((cinfo->max_h_samp_factor % compptr->h_samp_factor) == 0 &&
(cinfo->max_v_samp_factor % compptr->v_samp_factor) == 0)
cinfo->methods->unsubsample[ci] = int_unsubsample;
else
ERREXIT(cinfo->emethods, "Fractional subsampling not implemented yet");
}
cinfo->methods->unsubsample_init = unsubsample_init;
cinfo->methods->unsubsample_term = unsubsample_term;
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.