#if !defined(_FX_JPEG_TURBO_) | |
/* | |
* jcsample.c | |
* | |
* Copyright (C) 1991-1996, 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 downsampling routines. | |
* | |
* Downsampling input data is counted in "row groups". A row group | |
* is defined to be max_v_samp_factor pixel rows of each component, | |
* from which the downsampler produces v_samp_factor sample rows. | |
* A single row group is processed in each call to the downsampler module. | |
* | |
* The downsampler is responsible for edge-expansion of its output data | |
* to fill an integral number of DCT blocks horizontally. The source buffer | |
* may be modified if it is helpful for this purpose (the source buffer is | |
* allocated wide enough to correspond to the desired output width). | |
* The caller (the prep controller) is responsible for vertical padding. | |
* | |
* The downsampler may request "context rows" by setting need_context_rows | |
* during startup. In this case, the input arrays will contain at least | |
* one row group's worth of pixels above and below the passed-in data; | |
* the caller will create dummy rows at image top and bottom by replicating | |
* the first or last real pixel row. | |
* | |
* An excellent reference for image resampling is | |
* Digital Image Warping, George Wolberg, 1990. | |
* Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7. | |
* | |
* The downsampling algorithm used here is a simple average of the source | |
* pixels covered by the output pixel. The hi-falutin sampling literature | |
* refers to this as a "box filter". In general the characteristics of a box | |
* filter are not very good, but for the specific cases we normally use (1:1 | |
* and 2:1 ratios) the box is equivalent to a "triangle filter" which is not | |
* nearly so bad. If you intend to use other sampling ratios, you'd be well | |
* advised to improve this code. | |
* | |
* A simple input-smoothing capability is provided. This is mainly intended | |
* for cleaning up color-dithered GIF input files (if you find it inadequate, | |
* we suggest using an external filtering program such as pnmconvol). When | |
* enabled, each input pixel P is replaced by a weighted sum of itself and its | |
* eight neighbors. P's weight is 1-8*SF and each neighbor's weight is SF, | |
* where SF = (smoothing_factor / 1024). | |
* Currently, smoothing is only supported for 2h2v sampling factors. | |
*/ | |
#define JPEG_INTERNALS | |
#include "jinclude.h" | |
#include "jpeglib.h" | |
/* Pointer to routine to downsample a single component */ | |
typedef JMETHOD(void, downsample1_ptr, | |
(j_compress_ptr cinfo, jpeg_component_info * compptr, | |
JSAMPARRAY input_data, JSAMPARRAY output_data)); | |
/* Private subobject */ | |
typedef struct { | |
struct jpeg_downsampler pub; /* public fields */ | |
/* Downsampling method pointers, one per component */ | |
downsample1_ptr methods[MAX_COMPONENTS]; | |
} my_downsampler; | |
typedef my_downsampler * my_downsample_ptr; | |
/* | |
* Initialize for a downsampling pass. | |
*/ | |
METHODDEF(void) | |
start_pass_downsample (j_compress_ptr cinfo) | |
{ | |
/* no work for now */ | |
} | |
/* | |
* Expand a component horizontally from width input_cols to width output_cols, | |
* by duplicating the rightmost samples. | |
*/ | |
LOCAL(void) | |
expand_right_edge (JSAMPARRAY image_data, int num_rows, | |
JDIMENSION input_cols, JDIMENSION output_cols) | |
{ | |
register JSAMPROW ptr; | |
register JSAMPLE pixval; | |
register int count; | |
int row; | |
int numcols = (int) (output_cols - input_cols); | |
if (numcols > 0) { | |
for (row = 0; row < num_rows; row++) { | |
ptr = image_data[row] + input_cols; | |
pixval = ptr[-1]; /* don't need GETJSAMPLE() here */ | |
for (count = numcols; count > 0; count--) | |
*ptr++ = pixval; | |
} | |
} | |
} | |
/* | |
* Do downsampling for a whole row group (all components). | |
* | |
* In this version we simply downsample each component independently. | |
*/ | |
METHODDEF(void) | |
sep_downsample (j_compress_ptr cinfo, | |
JSAMPIMAGE input_buf, JDIMENSION in_row_index, | |
JSAMPIMAGE output_buf, JDIMENSION out_row_group_index) | |
{ | |
my_downsample_ptr downsample = (my_downsample_ptr) cinfo->downsample; | |
int ci; | |
jpeg_component_info * compptr; | |
JSAMPARRAY in_ptr, out_ptr; | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
in_ptr = input_buf[ci] + in_row_index; | |
out_ptr = output_buf[ci] + (out_row_group_index * compptr->v_samp_factor); | |
(*downsample->methods[ci]) (cinfo, compptr, in_ptr, out_ptr); | |
} | |
} | |
/* | |
* Downsample pixel values of a single component. | |
* One row group is processed per call. | |
* This version handles arbitrary integral sampling ratios, without smoothing. | |
* Note that this version is not actually used for customary sampling ratios. | |
*/ | |
METHODDEF(void) | |
int_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
JSAMPARRAY input_data, JSAMPARRAY output_data) | |
{ | |
int inrow, outrow, h_expand, v_expand, numpix, numpix2, h, v; | |
JDIMENSION outcol, outcol_h; /* outcol_h == outcol*h_expand */ | |
JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
JSAMPROW inptr, outptr; | |
INT32 outvalue; | |
h_expand = cinfo->max_h_samp_factor / compptr->h_samp_factor; | |
v_expand = cinfo->max_v_samp_factor / compptr->v_samp_factor; | |
numpix = h_expand * v_expand; | |
numpix2 = numpix/2; | |
/* Expand input data enough to let all the output samples be generated | |
* by the standard loop. Special-casing padded output would be more | |
* efficient. | |
*/ | |
expand_right_edge(input_data, cinfo->max_v_samp_factor, | |
cinfo->image_width, output_cols * h_expand); | |
inrow = 0; | |
for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
outptr = output_data[outrow]; | |
for (outcol = 0, outcol_h = 0; outcol < output_cols; | |
outcol++, outcol_h += h_expand) { | |
outvalue = 0; | |
for (v = 0; v < v_expand; v++) { | |
inptr = input_data[inrow+v] + outcol_h; | |
for (h = 0; h < h_expand; h++) { | |
outvalue += (INT32) GETJSAMPLE(*inptr++); | |
} | |
} | |
*outptr++ = (JSAMPLE) ((outvalue + numpix2) / numpix); | |
} | |
inrow += v_expand; | |
} | |
} | |
/* | |
* Downsample pixel values of a single component. | |
* This version handles the special case of a full-size component, | |
* without smoothing. | |
*/ | |
METHODDEF(void) | |
fullsize_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
JSAMPARRAY input_data, JSAMPARRAY output_data) | |
{ | |
/* Copy the data */ | |
jcopy_sample_rows(input_data, 0, output_data, 0, | |
cinfo->max_v_samp_factor, cinfo->image_width); | |
/* Edge-expand */ | |
expand_right_edge(output_data, cinfo->max_v_samp_factor, | |
cinfo->image_width, compptr->width_in_blocks * DCTSIZE); | |
} | |
/* | |
* Downsample pixel values of a single component. | |
* This version handles the common case of 2:1 horizontal and 1:1 vertical, | |
* without smoothing. | |
* | |
* A note about the "bias" calculations: when rounding fractional values to | |
* integer, we do not want to always round 0.5 up to the next integer. | |
* If we did that, we'd introduce a noticeable bias towards larger values. | |
* Instead, this code is arranged so that 0.5 will be rounded up or down at | |
* alternate pixel locations (a simple ordered dither pattern). | |
*/ | |
METHODDEF(void) | |
h2v1_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
JSAMPARRAY input_data, JSAMPARRAY output_data) | |
{ | |
int outrow; | |
JDIMENSION outcol; | |
JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
register JSAMPROW inptr, outptr; | |
register int bias; | |
/* Expand input data enough to let all the output samples be generated | |
* by the standard loop. Special-casing padded output would be more | |
* efficient. | |
*/ | |
expand_right_edge(input_data, cinfo->max_v_samp_factor, | |
cinfo->image_width, output_cols * 2); | |
for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
outptr = output_data[outrow]; | |
inptr = input_data[outrow]; | |
bias = 0; /* bias = 0,1,0,1,... for successive samples */ | |
for (outcol = 0; outcol < output_cols; outcol++) { | |
*outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr) + GETJSAMPLE(inptr[1]) | |
+ bias) >> 1); | |
bias ^= 1; /* 0=>1, 1=>0 */ | |
inptr += 2; | |
} | |
} | |
} | |
/* | |
* Downsample pixel values of a single component. | |
* This version handles the standard case of 2:1 horizontal and 2:1 vertical, | |
* without smoothing. | |
*/ | |
METHODDEF(void) | |
h2v2_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
JSAMPARRAY input_data, JSAMPARRAY output_data) | |
{ | |
int inrow, outrow; | |
JDIMENSION outcol; | |
JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
register JSAMPROW inptr0, inptr1, outptr; | |
register int bias; | |
/* Expand input data enough to let all the output samples be generated | |
* by the standard loop. Special-casing padded output would be more | |
* efficient. | |
*/ | |
expand_right_edge(input_data, cinfo->max_v_samp_factor, | |
cinfo->image_width, output_cols * 2); | |
inrow = 0; | |
for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
outptr = output_data[outrow]; | |
inptr0 = input_data[inrow]; | |
inptr1 = input_data[inrow+1]; | |
bias = 1; /* bias = 1,2,1,2,... for successive samples */ | |
for (outcol = 0; outcol < output_cols; outcol++) { | |
*outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) + | |
GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]) | |
+ bias) >> 2); | |
bias ^= 3; /* 1=>2, 2=>1 */ | |
inptr0 += 2; inptr1 += 2; | |
} | |
inrow += 2; | |
} | |
} | |
#ifdef INPUT_SMOOTHING_SUPPORTED | |
/* | |
* Downsample pixel values of a single component. | |
* This version handles the standard case of 2:1 horizontal and 2:1 vertical, | |
* with smoothing. One row of context is required. | |
*/ | |
METHODDEF(void) | |
h2v2_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
JSAMPARRAY input_data, JSAMPARRAY output_data) | |
{ | |
int inrow, outrow; | |
JDIMENSION colctr; | |
JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
register JSAMPROW inptr0, inptr1, above_ptr, below_ptr, outptr; | |
INT32 membersum, neighsum, memberscale, neighscale; | |
/* Expand input data enough to let all the output samples be generated | |
* by the standard loop. Special-casing padded output would be more | |
* efficient. | |
*/ | |
expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2, | |
cinfo->image_width, output_cols * 2); | |
/* We don't bother to form the individual "smoothed" input pixel values; | |
* we can directly compute the output which is the average of the four | |
* smoothed values. Each of the four member pixels contributes a fraction | |
* (1-8*SF) to its own smoothed image and a fraction SF to each of the three | |
* other smoothed pixels, therefore a total fraction (1-5*SF)/4 to the final | |
* output. The four corner-adjacent neighbor pixels contribute a fraction | |
* SF to just one smoothed pixel, or SF/4 to the final output; while the | |
* eight edge-adjacent neighbors contribute SF to each of two smoothed | |
* pixels, or SF/2 overall. In order to use integer arithmetic, these | |
* factors are scaled by 2^16 = 65536. | |
* Also recall that SF = smoothing_factor / 1024. | |
*/ | |
memberscale = 16384 - cinfo->smoothing_factor * 80; /* scaled (1-5*SF)/4 */ | |
neighscale = cinfo->smoothing_factor * 16; /* scaled SF/4 */ | |
inrow = 0; | |
for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
outptr = output_data[outrow]; | |
inptr0 = input_data[inrow]; | |
inptr1 = input_data[inrow+1]; | |
above_ptr = input_data[inrow-1]; | |
below_ptr = input_data[inrow+2]; | |
/* Special case for first column: pretend column -1 is same as column 0 */ | |
membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) + | |
GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]); | |
neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) + | |
GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) + | |
GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[2]) + | |
GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[2]); | |
neighsum += neighsum; | |
neighsum += GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[2]) + | |
GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[2]); | |
membersum = membersum * memberscale + neighsum * neighscale; | |
*outptr++ = (JSAMPLE) ((membersum + 32768) >> 16); | |
inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2; | |
for (colctr = output_cols - 2; colctr > 0; colctr--) { | |
/* sum of pixels directly mapped to this output element */ | |
membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) + | |
GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]); | |
/* sum of edge-neighbor pixels */ | |
neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) + | |
GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) + | |
GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[2]) + | |
GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[2]); | |
/* The edge-neighbors count twice as much as corner-neighbors */ | |
neighsum += neighsum; | |
/* Add in the corner-neighbors */ | |
neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[2]) + | |
GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[2]); | |
/* form final output scaled up by 2^16 */ | |
membersum = membersum * memberscale + neighsum * neighscale; | |
/* round, descale and output it */ | |
*outptr++ = (JSAMPLE) ((membersum + 32768) >> 16); | |
inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2; | |
} | |
/* Special case for last column */ | |
membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) + | |
GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]); | |
neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) + | |
GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) + | |
GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[1]) + | |
GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[1]); | |
neighsum += neighsum; | |
neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[1]) + | |
GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[1]); | |
membersum = membersum * memberscale + neighsum * neighscale; | |
*outptr = (JSAMPLE) ((membersum + 32768) >> 16); | |
inrow += 2; | |
} | |
} | |
/* | |
* Downsample pixel values of a single component. | |
* This version handles the special case of a full-size component, | |
* with smoothing. One row of context is required. | |
*/ | |
METHODDEF(void) | |
fullsize_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr, | |
JSAMPARRAY input_data, JSAMPARRAY output_data) | |
{ | |
int outrow; | |
JDIMENSION colctr; | |
JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
register JSAMPROW inptr, above_ptr, below_ptr, outptr; | |
INT32 membersum, neighsum, memberscale, neighscale; | |
int colsum, lastcolsum, nextcolsum; | |
/* Expand input data enough to let all the output samples be generated | |
* by the standard loop. Special-casing padded output would be more | |
* efficient. | |
*/ | |
expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2, | |
cinfo->image_width, output_cols); | |
/* Each of the eight neighbor pixels contributes a fraction SF to the | |
* smoothed pixel, while the main pixel contributes (1-8*SF). In order | |
* to use integer arithmetic, these factors are multiplied by 2^16 = 65536. | |
* Also recall that SF = smoothing_factor / 1024. | |
*/ | |
memberscale = 65536L - cinfo->smoothing_factor * 512L; /* scaled 1-8*SF */ | |
neighscale = cinfo->smoothing_factor * 64; /* scaled SF */ | |
for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
outptr = output_data[outrow]; | |
inptr = input_data[outrow]; | |
above_ptr = input_data[outrow-1]; | |
below_ptr = input_data[outrow+1]; | |
/* Special case for first column */ | |
colsum = GETJSAMPLE(*above_ptr++) + GETJSAMPLE(*below_ptr++) + | |
GETJSAMPLE(*inptr); | |
membersum = GETJSAMPLE(*inptr++); | |
nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) + | |
GETJSAMPLE(*inptr); | |
neighsum = colsum + (colsum - membersum) + nextcolsum; | |
membersum = membersum * memberscale + neighsum * neighscale; | |
*outptr++ = (JSAMPLE) ((membersum + 32768) >> 16); | |
lastcolsum = colsum; colsum = nextcolsum; | |
for (colctr = output_cols - 2; colctr > 0; colctr--) { | |
membersum = GETJSAMPLE(*inptr++); | |
above_ptr++; below_ptr++; | |
nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) + | |
GETJSAMPLE(*inptr); | |
neighsum = lastcolsum + (colsum - membersum) + nextcolsum; | |
membersum = membersum * memberscale + neighsum * neighscale; | |
*outptr++ = (JSAMPLE) ((membersum + 32768) >> 16); | |
lastcolsum = colsum; colsum = nextcolsum; | |
} | |
/* Special case for last column */ | |
membersum = GETJSAMPLE(*inptr); | |
neighsum = lastcolsum + (colsum - membersum) + colsum; | |
membersum = membersum * memberscale + neighsum * neighscale; | |
*outptr = (JSAMPLE) ((membersum + 32768) >> 16); | |
} | |
} | |
#endif /* INPUT_SMOOTHING_SUPPORTED */ | |
/* | |
* Module initialization routine for downsampling. | |
* Note that we must select a routine for each component. | |
*/ | |
GLOBAL(void) | |
jinit_downsampler (j_compress_ptr cinfo) | |
{ | |
my_downsample_ptr downsample; | |
int ci; | |
jpeg_component_info * compptr; | |
boolean smoothok = TRUE; | |
downsample = (my_downsample_ptr) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
SIZEOF(my_downsampler)); | |
cinfo->downsample = (struct jpeg_downsampler *) downsample; | |
downsample->pub.start_pass = start_pass_downsample; | |
downsample->pub.downsample = sep_downsample; | |
downsample->pub.need_context_rows = FALSE; | |
if (cinfo->CCIR601_sampling) | |
ERREXIT(cinfo, JERR_CCIR601_NOTIMPL); | |
/* Verify we can handle the sampling factors, and set up method pointers */ | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
if (compptr->h_samp_factor == cinfo->max_h_samp_factor && | |
compptr->v_samp_factor == cinfo->max_v_samp_factor) { | |
#ifdef INPUT_SMOOTHING_SUPPORTED | |
if (cinfo->smoothing_factor) { | |
downsample->methods[ci] = fullsize_smooth_downsample; | |
downsample->pub.need_context_rows = TRUE; | |
} else | |
#endif | |
downsample->methods[ci] = fullsize_downsample; | |
} else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor && | |
compptr->v_samp_factor == cinfo->max_v_samp_factor) { | |
smoothok = FALSE; | |
downsample->methods[ci] = h2v1_downsample; | |
} else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor && | |
compptr->v_samp_factor * 2 == cinfo->max_v_samp_factor) { | |
#ifdef INPUT_SMOOTHING_SUPPORTED | |
if (cinfo->smoothing_factor) { | |
downsample->methods[ci] = h2v2_smooth_downsample; | |
downsample->pub.need_context_rows = TRUE; | |
} else | |
#endif | |
downsample->methods[ci] = h2v2_downsample; | |
} else if ((cinfo->max_h_samp_factor % compptr->h_samp_factor) == 0 && | |
(cinfo->max_v_samp_factor % compptr->v_samp_factor) == 0) { | |
smoothok = FALSE; | |
downsample->methods[ci] = int_downsample; | |
} else | |
ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL); | |
} | |
#ifdef INPUT_SMOOTHING_SUPPORTED | |
if (cinfo->smoothing_factor && !smoothok) | |
TRACEMS(cinfo, 0, JTRC_SMOOTH_NOTIMPL); | |
#endif | |
} | |
#endif //_FX_JPEG_TURBO_ |