1 /*
2  * jdsample.c
3  *
4  * Copyright (C) 1991-1996, Thomas G. Lane.
5  * Modified 2002-2008 by Guido Vollbeding.
6  * This file is part of the Independent JPEG Group's software.
7  * For conditions of distribution and use, see the accompanying README file.
8  *
9  * This file contains upsampling routines.
10  *
11  * Upsampling input data is counted in "row groups".  A row group
12  * is defined to be (v_samp_factor * DCT_v_scaled_size / min_DCT_v_scaled_size)
13  * sample rows of each component.  Upsampling will normally produce
14  * max_v_samp_factor pixel rows from each row group (but this could vary
15  * if the upsampler is applying a scale factor of its own).
16  *
17  * An excellent reference for image resampling is
18  *   Digital Image Warping, George Wolberg, 1990.
19  *   Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
20  */
21 
22 #define JPEG_INTERNALS
23 #include "jinclude.h"
24 #include "jpeglib.h"
25 
26 
27 /* Pointer to routine to upsample a single component */
28 typedef JMETHOD(void, upsample1_ptr,
29 		(j_decompress_ptr cinfo, jpeg_component_info * compptr,
30 		 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
31 
32 /* Private subobject */
33 
34 typedef struct {
35   struct jpeg_upsampler pub;	/* public fields */
36 
37   /* Color conversion buffer.  When using separate upsampling and color
38    * conversion steps, this buffer holds one upsampled row group until it
39    * has been color converted and output.
40    * Note: we do not allocate any storage for component(s) which are full-size,
41    * ie do not need rescaling.  The corresponding entry of color_buf[] is
42    * simply set to point to the input data array, thereby avoiding copying.
43    */
44   JSAMPARRAY color_buf[MAX_COMPONENTS];
45 
46   /* Per-component upsampling method pointers */
47   upsample1_ptr methods[MAX_COMPONENTS];
48 
49   int next_row_out;		/* counts rows emitted from color_buf */
50   JDIMENSION rows_to_go;	/* counts rows remaining in image */
51 
52   /* Height of an input row group for each component. */
53   int rowgroup_height[MAX_COMPONENTS];
54 
55   /* These arrays save pixel expansion factors so that int_expand need not
56    * recompute them each time.  They are unused for other upsampling methods.
57    */
58   UINT8 h_expand[MAX_COMPONENTS];
59   UINT8 v_expand[MAX_COMPONENTS];
60 } my_upsampler;
61 
62 typedef my_upsampler * my_upsample_ptr;
63 
64 
65 /*
66  * Initialize for an upsampling pass.
67  */
68 
69 METHODDEF(void)
start_pass_upsample(j_decompress_ptr cinfo)70 start_pass_upsample (j_decompress_ptr cinfo)
71 {
72   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
73 
74   /* Mark the conversion buffer empty */
75   upsample->next_row_out = cinfo->max_v_samp_factor;
76   /* Initialize total-height counter for detecting bottom of image */
77   upsample->rows_to_go = cinfo->output_height;
78 }
79 
80 
81 /*
82  * Control routine to do upsampling (and color conversion).
83  *
84  * In this version we upsample each component independently.
85  * We upsample one row group into the conversion buffer, then apply
86  * color conversion a row at a time.
87  */
88 
89 METHODDEF(void)
sep_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)90 sep_upsample (j_decompress_ptr cinfo,
91 	      JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
92 	      JDIMENSION in_row_groups_avail,
93 	      JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
94 	      JDIMENSION out_rows_avail)
95 {
96   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
97   int ci;
98   jpeg_component_info * compptr;
99   JDIMENSION num_rows;
100 
101   /* Fill the conversion buffer, if it's empty */
102   if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
103     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
104 	 ci++, compptr++) {
105       /* Invoke per-component upsample method.  Notice we pass a POINTER
106        * to color_buf[ci], so that fullsize_upsample can change it.
107        */
108       (*upsample->methods[ci]) (cinfo, compptr,
109 	input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
110 	upsample->color_buf + ci);
111     }
112     upsample->next_row_out = 0;
113   }
114 
115   /* Color-convert and emit rows */
116 
117   /* How many we have in the buffer: */
118   num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
119   /* Not more than the distance to the end of the image.  Need this test
120    * in case the image height is not a multiple of max_v_samp_factor:
121    */
122   if (num_rows > upsample->rows_to_go)
123     num_rows = upsample->rows_to_go;
124   /* And not more than what the client can accept: */
125   out_rows_avail -= *out_row_ctr;
126   if (num_rows > out_rows_avail)
127     num_rows = out_rows_avail;
128 
129   (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
130 				     (JDIMENSION) upsample->next_row_out,
131 				     output_buf + *out_row_ctr,
132 				     (int) num_rows);
133 
134   /* Adjust counts */
135   *out_row_ctr += num_rows;
136   upsample->rows_to_go -= num_rows;
137   upsample->next_row_out += num_rows;
138   /* When the buffer is emptied, declare this input row group consumed */
139   if (upsample->next_row_out >= cinfo->max_v_samp_factor)
140     (*in_row_group_ctr)++;
141 }
142 
143 
144 /*
145  * These are the routines invoked by sep_upsample to upsample pixel values
146  * of a single component.  One row group is processed per call.
147  */
148 
149 
150 /*
151  * For full-size components, we just make color_buf[ci] point at the
152  * input buffer, and thus avoid copying any data.  Note that this is
153  * safe only because sep_upsample doesn't declare the input row group
154  * "consumed" until we are done color converting and emitting it.
155  */
156 
157 METHODDEF(void)
fullsize_upsample(j_decompress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY * output_data_ptr)158 fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
159 		   JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
160 {
161   *output_data_ptr = input_data;
162 }
163 
164 
165 /*
166  * This is a no-op version used for "uninteresting" components.
167  * These components will not be referenced by color conversion.
168  */
169 
170 METHODDEF(void)
noop_upsample(j_decompress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY * output_data_ptr)171 noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
172 	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
173 {
174   *output_data_ptr = NULL;	/* safety check */
175 }
176 
177 
178 /*
179  * This version handles any integral sampling ratios.
180  * This is not used for typical JPEG files, so it need not be fast.
181  * Nor, for that matter, is it particularly accurate: the algorithm is
182  * simple replication of the input pixel onto the corresponding output
183  * pixels.  The hi-falutin sampling literature refers to this as a
184  * "box filter".  A box filter tends to introduce visible artifacts,
185  * so if you are actually going to use 3:1 or 4:1 sampling ratios
186  * you would be well advised to improve this code.
187  */
188 
189 METHODDEF(void)
int_upsample(j_decompress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY * output_data_ptr)190 int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
191 	      JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
192 {
193   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
194   JSAMPARRAY output_data = *output_data_ptr;
195   register JSAMPROW inptr, outptr;
196   register JSAMPLE invalue;
197   register int h;
198   JSAMPROW outend;
199   int h_expand, v_expand;
200   int inrow, outrow;
201 
202   h_expand = upsample->h_expand[compptr->component_index];
203   v_expand = upsample->v_expand[compptr->component_index];
204 
205   inrow = outrow = 0;
206   while (outrow < cinfo->max_v_samp_factor) {
207     /* Generate one output row with proper horizontal expansion */
208     inptr = input_data[inrow];
209     outptr = output_data[outrow];
210     outend = outptr + cinfo->output_width;
211     while (outptr < outend) {
212       invalue = *inptr++;	/* don't need GETJSAMPLE() here */
213       for (h = h_expand; h > 0; h--) {
214 	*outptr++ = invalue;
215       }
216     }
217     /* Generate any additional output rows by duplicating the first one */
218     if (v_expand > 1) {
219       jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
220 			v_expand-1, cinfo->output_width);
221     }
222     inrow++;
223     outrow += v_expand;
224   }
225 }
226 
227 
228 /*
229  * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
230  * It's still a box filter.
231  */
232 
233 METHODDEF(void)
h2v1_upsample(j_decompress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY * output_data_ptr)234 h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
235 	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
236 {
237   JSAMPARRAY output_data = *output_data_ptr;
238   register JSAMPROW inptr, outptr;
239   register JSAMPLE invalue;
240   JSAMPROW outend;
241   int outrow;
242 
243   for (outrow = 0; outrow < cinfo->max_v_samp_factor; outrow++) {
244     inptr = input_data[outrow];
245     outptr = output_data[outrow];
246     outend = outptr + cinfo->output_width;
247     while (outptr < outend) {
248       invalue = *inptr++;	/* don't need GETJSAMPLE() here */
249       *outptr++ = invalue;
250       *outptr++ = invalue;
251     }
252   }
253 }
254 
255 
256 /*
257  * Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
258  * It's still a box filter.
259  */
260 
261 METHODDEF(void)
h2v2_upsample(j_decompress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY input_data,JSAMPARRAY * output_data_ptr)262 h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
263 	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
264 {
265   JSAMPARRAY output_data = *output_data_ptr;
266   register JSAMPROW inptr, outptr;
267   register JSAMPLE invalue;
268   JSAMPROW outend;
269   int inrow, outrow;
270 
271   inrow = outrow = 0;
272   while (outrow < cinfo->max_v_samp_factor) {
273     inptr = input_data[inrow];
274     outptr = output_data[outrow];
275     outend = outptr + cinfo->output_width;
276     while (outptr < outend) {
277       invalue = *inptr++;	/* don't need GETJSAMPLE() here */
278       *outptr++ = invalue;
279       *outptr++ = invalue;
280     }
281     jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
282 		      1, cinfo->output_width);
283     inrow++;
284     outrow += 2;
285   }
286 }
287 
288 
289 /*
290  * Module initialization routine for upsampling.
291  */
292 
293 GLOBAL(void)
jinit_upsampler(j_decompress_ptr cinfo)294 jinit_upsampler (j_decompress_ptr cinfo)
295 {
296   my_upsample_ptr upsample;
297   int ci;
298   jpeg_component_info * compptr;
299   boolean need_buffer;
300   int h_in_group, v_in_group, h_out_group, v_out_group;
301 
302   upsample = (my_upsample_ptr)
303     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
304 				SIZEOF(my_upsampler));
305   cinfo->upsample = (struct jpeg_upsampler *) upsample;
306   upsample->pub.start_pass = start_pass_upsample;
307   upsample->pub.upsample = sep_upsample;
308   upsample->pub.need_context_rows = FALSE; /* until we find out differently */
309 
310   if (cinfo->CCIR601_sampling)	/* this isn't supported */
311     ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
312 
313   /* Verify we can handle the sampling factors, select per-component methods,
314    * and create storage as needed.
315    */
316   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
317        ci++, compptr++) {
318     /* Compute size of an "input group" after IDCT scaling.  This many samples
319      * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
320      */
321     h_in_group = (compptr->h_samp_factor * compptr->DCT_h_scaled_size) /
322 		 cinfo->min_DCT_h_scaled_size;
323     v_in_group = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) /
324 		 cinfo->min_DCT_v_scaled_size;
325     h_out_group = cinfo->max_h_samp_factor;
326     v_out_group = cinfo->max_v_samp_factor;
327     upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
328     need_buffer = TRUE;
329     if (! compptr->component_needed) {
330       /* Don't bother to upsample an uninteresting component. */
331       upsample->methods[ci] = noop_upsample;
332       need_buffer = FALSE;
333     } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
334       /* Fullsize components can be processed without any work. */
335       upsample->methods[ci] = fullsize_upsample;
336       need_buffer = FALSE;
337     } else if (h_in_group * 2 == h_out_group &&
338 	       v_in_group == v_out_group) {
339       /* Special case for 2h1v upsampling */
340       upsample->methods[ci] = h2v1_upsample;
341     } else if (h_in_group * 2 == h_out_group &&
342 	       v_in_group * 2 == v_out_group) {
343       /* Special case for 2h2v upsampling */
344       upsample->methods[ci] = h2v2_upsample;
345     } else if ((h_out_group % h_in_group) == 0 &&
346 	       (v_out_group % v_in_group) == 0) {
347       /* Generic integral-factors upsampling method */
348       upsample->methods[ci] = int_upsample;
349       upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
350       upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
351     } else
352       ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
353     if (need_buffer) {
354       upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
355 	((j_common_ptr) cinfo, JPOOL_IMAGE,
356 	 (JDIMENSION) jround_up((long) cinfo->output_width,
357 				(long) cinfo->max_h_samp_factor),
358 	 (JDIMENSION) cinfo->max_v_samp_factor);
359     }
360   }
361 }
362