git.sesse.net Git - qscale/blob - qscale.c

   1 /*
   2  * qscale: Quick, high-quality JPEG-to-JPEG scaler.
   3  * Copyright (C) 2008 Steinar H. Gunderson <sgunderson@bigfoot.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, version 2 of the License.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  17  */
  18
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <stdlib.h>
  22 #include "jpeglib.h"
  23 #include "libqscale.h"
  24
  25 int main(int argc, char **argv)
  26 {
  27         /* user-settable parameters */
  28         unsigned nominal_w = atoi(argv[1]);
  29         unsigned nominal_h = atoi(argv[2]);
  30         unsigned samp_h0 = 2, samp_v0 = 2;
  31         unsigned samp_h1 = 1, samp_v1 = 1;
  32         unsigned samp_h2 = 1, samp_v2 = 1;
  33         unsigned jpeg_quality = 85;
  34         /* end */
  35
  36         qscale_img *img = qscale_load_jpeg_from_stdio(stdin);
  37         qscale_img *scaled = qscale_scale(img, nominal_w, nominal_h, samp_h0, samp_v0, samp_h1, samp_v1, samp_h2, samp_v2, LANCZOS);
  38         qscale_destroy(img);
  39
  40         struct jpeg_compress_struct cinfo;
  41         struct jpeg_error_mgr jerr;
  42         cinfo.err = jpeg_std_error(&jerr);
  43         jpeg_create_compress(&cinfo);
  44         jpeg_stdio_dest(&cinfo, stdout);
  45         cinfo.input_components = 3;
  46         jpeg_set_defaults(&cinfo);
  47         jpeg_set_quality(&cinfo, jpeg_quality, FALSE);
  48         cinfo.image_width = nominal_w;
  49         cinfo.image_height = nominal_h;
  50         cinfo.raw_data_in = TRUE;
  51         jpeg_set_colorspace(&cinfo, JCS_YCbCr);
  52         cinfo.comp_info[0].h_samp_factor = samp_h0;
  53         cinfo.comp_info[0].v_samp_factor = samp_v0;
  54         cinfo.comp_info[1].h_samp_factor = samp_h1;
  55         cinfo.comp_info[1].v_samp_factor = samp_v1;
  56         cinfo.comp_info[2].h_samp_factor = samp_h2;
  57         cinfo.comp_info[2].v_samp_factor = samp_v2;
  58         jpeg_start_compress(&cinfo, TRUE);
  59
  60         unsigned dstride0 = (scaled->w0 + DCTSIZE-1) & ~(DCTSIZE-1);
  61         unsigned dstride1 = (scaled->w1 + DCTSIZE-1) & ~(DCTSIZE-1);
  62         unsigned dstride2 = (scaled->w2 + DCTSIZE-1) & ~(DCTSIZE-1);
  63
  64         int total_lines = 0;
  65         int blocks = 0;
  66         while (total_lines < cinfo.comp_info[0].height_in_blocks * DCTSIZE) {
  67                 unsigned max_lines = cinfo.max_v_samp_factor * DCTSIZE;
  68
  69                 JSAMPROW y_row_ptrs[max_lines];
  70                 JSAMPROW cb_row_ptrs[max_lines];
  71                 JSAMPROW cr_row_ptrs[max_lines];
  72                 JSAMPROW* ptrs[] = { y_row_ptrs, cb_row_ptrs, cr_row_ptrs };
  73                 int i;
  74
  75                 for (i = 0; i < max_lines; ++i) {
  76                         /* simple edge extension */
  77                         int yline = i + blocks*DCTSIZE*cinfo.comp_info[0].v_samp_factor;
  78                         if (yline > scaled->h0 - 1)
  79                                 yline = scaled->h0 - 1;
  80
  81                         int cbline = i + blocks*DCTSIZE*cinfo.comp_info[1].v_samp_factor;
  82                         if (cbline > scaled->h1 - 1)
  83                                 cbline = scaled->h2 - 1;
  84
  85                         int crline = i + blocks*DCTSIZE*cinfo.comp_info[2].v_samp_factor;
  86                         if (crline > scaled->h2 - 1)
  87                                 crline = scaled->h2 - 1;
  88
  89                         y_row_ptrs[i]  = scaled->data_y  + yline * dstride0;
  90                         cb_row_ptrs[i] = scaled->data_cb + cbline * dstride1;
  91                         cr_row_ptrs[i] = scaled->data_cr + crline * dstride2;
  92                 }
  93
  94                 total_lines += max_lines;
  95                 ++blocks;
  96
  97                 jpeg_write_raw_data(&cinfo, ptrs, max_lines);
  98         }
  99         jpeg_finish_compress(&cinfo);
 100         jpeg_destroy_compress(&cinfo);
 101
 102         return 0;
 103 }
 104