The Tor Browser: media/libjpeg/jdsample.c@b8a032363ba2 (annotated)

media/libjpeg/jdsample.c@b8a032363ba2 (annotated)

media/libjpeg/jdsample.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*
  * jdsample.c
  *
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1991-1996, Thomas G. Lane.
  * libjpeg-turbo Modifications:
  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
  * Copyright (C) 2010, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains upsampling routines.
  *
  * Upsampling input data is counted in "row groups".  A row group
  * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
  * sample rows of each component.  Upsampling will normally produce
  * max_v_samp_factor pixel rows from each row group (but this could vary
  * if the upsampler is applying a scale factor of its own).
  *
  * 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.
  */
 #define JPEG_INTERNALS
 #include "jinclude.h"
 #include "jpeglib.h"
 #include "jsimd.h"
 #include "jpegcomp.h"
 /* Pointer to routine to upsample a single component */
 typedef JMETHOD(void, upsample1_ptr,
 		(j_decompress_ptr cinfo, jpeg_component_info * compptr,
 		 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
 /* Private subobject */
 typedef struct {
   struct jpeg_upsampler pub;	/* public fields */
   /* Color conversion buffer.  When using separate upsampling and color
    * conversion steps, this buffer holds one upsampled row group until it
    * has been color converted and output.
    * Note: we do not allocate any storage for component(s) which are full-size,
    * ie do not need rescaling.  The corresponding entry of color_buf[] is
    * simply set to point to the input data array, thereby avoiding copying.
    */
   JSAMPARRAY color_buf[MAX_COMPONENTS];
   /* Per-component upsampling method pointers */
   upsample1_ptr methods[MAX_COMPONENTS];
   int next_row_out;		/* counts rows emitted from color_buf */
   JDIMENSION rows_to_go;	/* counts rows remaining in image */
   /* Height of an input row group for each component. */
   int rowgroup_height[MAX_COMPONENTS];
   /* These arrays save pixel expansion factors so that int_expand need not
    * recompute them each time.  They are unused for other upsampling methods.
    */
   UINT8 h_expand[MAX_COMPONENTS];
   UINT8 v_expand[MAX_COMPONENTS];
 } my_upsampler;
 typedef my_upsampler * my_upsample_ptr;
 /*
  * Initialize for an upsampling pass.
  */
 METHODDEF(void)
 start_pass_upsample (j_decompress_ptr cinfo)
 {
   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
   /* Mark the conversion buffer empty */
   upsample->next_row_out = cinfo->max_v_samp_factor;
   /* Initialize total-height counter for detecting bottom of image */
   upsample->rows_to_go = cinfo->output_height;
 }
 /*
  * Control routine to do upsampling (and color conversion).
  *
  * In this version we upsample each component independently.
  * We upsample one row group into the conversion buffer, then apply
  * color conversion a row at a time.
  */
 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)
 {
   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
   int ci;
   jpeg_component_info * compptr;
   JDIMENSION num_rows;
   /* Fill the conversion buffer, if it's empty */
   if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 	 ci++, compptr++) {
       /* Invoke per-component upsample method.  Notice we pass a POINTER
        * to color_buf[ci], so that fullsize_upsample can change it.
        */
       (*upsample->methods[ci]) (cinfo, compptr,
 	input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
 	upsample->color_buf + ci);
     }
     upsample->next_row_out = 0;
   }
   /* Color-convert and emit rows */
   /* How many we have in the buffer: */
   num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
   /* Not more than the distance to the end of the image.  Need this test
    * in case the image height is not a multiple of max_v_samp_factor:
    */
   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;
   (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
 				     (JDIMENSION) upsample->next_row_out,
 				     output_buf + *out_row_ctr,
 				     (int) num_rows);
   /* Adjust counts */
   *out_row_ctr += num_rows;
   upsample->rows_to_go -= num_rows;
   upsample->next_row_out += num_rows;
   /* When the buffer is emptied, declare this input row group consumed */
   if (upsample->next_row_out >= cinfo->max_v_samp_factor)
     (*in_row_group_ctr)++;
 }
 /*
  * These are the routines invoked by sep_upsample to upsample pixel values
  * of a single component.  One row group is processed per call.
  */
 /*
  * For full-size components, we just make color_buf[ci] point at the
  * input buffer, and thus avoid copying any data.  Note that this is
  * safe only because sep_upsample doesn't declare the input row group
  * "consumed" until we are done color converting and emitting it.
  */
 METHODDEF(void)
 fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 		   JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
 {
   *output_data_ptr = input_data;
 }
 /*
  * This is a no-op version used for "uninteresting" components.
  * These components will not be referenced by color conversion.
  */
 METHODDEF(void)
 noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
 {
   *output_data_ptr = NULL;	/* safety check */
 }
 /*
  * This version handles any integral sampling ratios.
  * This is not used for typical JPEG files, so it need not be fast.
  * Nor, for that matter, is it particularly accurate: the algorithm is
  * simple replication of the input pixel onto the corresponding output
  * pixels.  The hi-falutin sampling literature refers to this as a
  * "box filter".  A box filter tends to introduce visible artifacts,
  * so if you are actually going to use 3:1 or 4:1 sampling ratios
  * you would be well advised to improve this code.
  */
 METHODDEF(void)
 int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 	      JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
 {
   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
   JSAMPARRAY output_data = *output_data_ptr;
   register JSAMPROW inptr, outptr;
   register JSAMPLE invalue;
   register int h;
   JSAMPROW outend;
   int h_expand, v_expand;
   int inrow, outrow;
   h_expand = upsample->h_expand[compptr->component_index];
   v_expand = upsample->v_expand[compptr->component_index];
   inrow = outrow = 0;
   while (outrow < cinfo->max_v_samp_factor) {
     /* Generate one output row with proper horizontal expansion */
     inptr = input_data[inrow];
     outptr = output_data[outrow];
     outend = outptr + cinfo->output_width;
     while (outptr < outend) {
       invalue = *inptr++;	/* don't need GETJSAMPLE() here */
       for (h = h_expand; h > 0; h--) {
 	*outptr++ = invalue;
       }
     }
     /* Generate any additional output rows by duplicating the first one */
     if (v_expand > 1) {
       jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
 			v_expand-1, cinfo->output_width);
     }
     inrow++;
     outrow += v_expand;
   }
 }
 /*
  * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
  * It's still a box filter.
  */
 METHODDEF(void)
 h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
 {
   JSAMPARRAY output_data = *output_data_ptr;
   register JSAMPROW inptr, outptr;
   register JSAMPLE invalue;
   JSAMPROW outend;
   int inrow;
   for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
     inptr = input_data[inrow];
     outptr = output_data[inrow];
     outend = outptr + cinfo->output_width;
     while (outptr < outend) {
       invalue = *inptr++;	/* don't need GETJSAMPLE() here */
       *outptr++ = invalue;
       *outptr++ = invalue;
     }
   }
 }
 /*
  * Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
  * It's still a box filter.
  */
 METHODDEF(void)
 h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
 {
   JSAMPARRAY output_data = *output_data_ptr;
   register JSAMPROW inptr, outptr;
   register JSAMPLE invalue;
   JSAMPROW outend;
   int inrow, outrow;
   inrow = outrow = 0;
   while (outrow < cinfo->max_v_samp_factor) {
     inptr = input_data[inrow];
     outptr = output_data[outrow];
     outend = outptr + cinfo->output_width;
     while (outptr < outend) {
       invalue = *inptr++;	/* don't need GETJSAMPLE() here */
       *outptr++ = invalue;
       *outptr++ = invalue;
     }
     jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
 , cinfo->output_width);
     inrow++;
     outrow += 2;
   }
 }
 /*
  * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical.
  *
  * The upsampling algorithm is linear interpolation between pixel centers,
  * also known as a "triangle filter".  This is a good compromise between
  * speed and visual quality.  The centers of the output pixels are 1/4 and 3/4
  * of the way between input pixel centers.
  *
  * 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_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 		     JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
 {
   JSAMPARRAY output_data = *output_data_ptr;
   register JSAMPROW inptr, outptr;
   register int invalue;
   register JDIMENSION colctr;
   int inrow;
   for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
     inptr = input_data[inrow];
     outptr = output_data[inrow];
     /* Special case for first column */
     invalue = GETJSAMPLE(*inptr++);
     *outptr++ = (JSAMPLE) invalue;
     *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2);
     for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
       /* General case: 3/4 * nearer pixel + 1/4 * further pixel */
       invalue = GETJSAMPLE(*inptr++) * 3;
       *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2);
       *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2);
     }
     /* Special case for last column */
     invalue = GETJSAMPLE(*inptr);
     *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2);
     *outptr++ = (JSAMPLE) invalue;
   }
 }
 /*
  * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical.
  * Again a triangle filter; see comments for h2v1 case, above.
  *
  * It is OK for us to reference the adjacent input rows because we demanded
  * context from the main buffer controller (see initialization code).
  */
 METHODDEF(void)
 h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 		     JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
 {
   JSAMPARRAY output_data = *output_data_ptr;
   register JSAMPROW inptr0, inptr1, outptr;
 #if BITS_IN_JSAMPLE == 8
   register int thiscolsum, lastcolsum, nextcolsum;
 #else
   register INT32 thiscolsum, lastcolsum, nextcolsum;
 #endif
   register JDIMENSION colctr;
   int inrow, outrow, v;
   inrow = outrow = 0;
   while (outrow < cinfo->max_v_samp_factor) {
     for (v = 0; v < 2; v++) {
       /* inptr0 points to nearest input row, inptr1 points to next nearest */
       inptr0 = input_data[inrow];
       if (v == 0)		/* next nearest is row above */
 	inptr1 = input_data[inrow-1];
       else			/* next nearest is row below */
 	inptr1 = input_data[inrow+1];
       outptr = output_data[outrow++];
       /* Special case for first column */
       thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
       nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
       *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4);
       *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
       lastcolsum = thiscolsum; thiscolsum = nextcolsum;
       for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
 	/* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
 	/* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
 	nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
 	*outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
 	*outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
 	lastcolsum = thiscolsum; thiscolsum = nextcolsum;
       }
       /* Special case for last column */
       *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
       *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4);
     }
     inrow++;
   }
 }
 /*
  * Module initialization routine for upsampling.
  */
 GLOBAL(void)
 jinit_upsampler (j_decompress_ptr cinfo)
 {
   my_upsample_ptr upsample;
   int ci;
   jpeg_component_info * compptr;
   boolean need_buffer, do_fancy;
   int h_in_group, v_in_group, h_out_group, v_out_group;
   upsample = (my_upsample_ptr)
     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 				SIZEOF(my_upsampler));
   cinfo->upsample = (struct jpeg_upsampler *) upsample;
   upsample->pub.start_pass = start_pass_upsample;
   upsample->pub.upsample = sep_upsample;
   upsample->pub.need_context_rows = FALSE; /* until we find out differently */
   if (cinfo->CCIR601_sampling)	/* this isn't supported */
     ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
   /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
    * so don't ask for it.
    */
   do_fancy = cinfo->do_fancy_upsampling && cinfo->_min_DCT_scaled_size > 1;
   /* Verify we can handle the sampling factors, select per-component methods,
    * and create storage as needed.
    */
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* Compute size of an "input group" after IDCT scaling.  This many samples
      * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
      */
     h_in_group = (compptr->h_samp_factor * compptr->_DCT_scaled_size) /
 		 cinfo->_min_DCT_scaled_size;
     v_in_group = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
 		 cinfo->_min_DCT_scaled_size;
     h_out_group = cinfo->max_h_samp_factor;
     v_out_group = cinfo->max_v_samp_factor;
     upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
     need_buffer = TRUE;
     if (! compptr->component_needed) {
       /* Don't bother to upsample an uninteresting component. */
       upsample->methods[ci] = noop_upsample;
       need_buffer = FALSE;
     } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
       /* Fullsize components can be processed without any work. */
       upsample->methods[ci] = fullsize_upsample;
       need_buffer = FALSE;
     } else if (h_in_group * 2 == h_out_group &&
 	       v_in_group == v_out_group) {
       /* Special cases for 2h1v upsampling */
       if (do_fancy && compptr->downsampled_width > 2) {
 	if (jsimd_can_h2v1_fancy_upsample())
 	  upsample->methods[ci] = jsimd_h2v1_fancy_upsample;
 	else
 	  upsample->methods[ci] = h2v1_fancy_upsample;
       } else {
 	if (jsimd_can_h2v1_upsample())
 	  upsample->methods[ci] = jsimd_h2v1_upsample;
 	else
 	  upsample->methods[ci] = h2v1_upsample;
       }
     } else if (h_in_group * 2 == h_out_group &&
 	       v_in_group * 2 == v_out_group) {
       /* Special cases for 2h2v upsampling */
       if (do_fancy && compptr->downsampled_width > 2) {
 	if (jsimd_can_h2v2_fancy_upsample())
 	  upsample->methods[ci] = jsimd_h2v2_fancy_upsample;
 	else
 	  upsample->methods[ci] = h2v2_fancy_upsample;
 	upsample->pub.need_context_rows = TRUE;
       } else {
 	if (jsimd_can_h2v2_upsample())
 	  upsample->methods[ci] = jsimd_h2v2_upsample;
 	else
 	  upsample->methods[ci] = h2v2_upsample;
       }
     } else if ((h_out_group % h_in_group) == 0 &&
 	       (v_out_group % v_in_group) == 0) {
       /* Generic integral-factors upsampling method */
       upsample->methods[ci] = int_upsample;
       upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
       upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
     } else
       ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
     if (need_buffer) {
       upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
 	((j_common_ptr) cinfo, JPOOL_IMAGE,
 	 (JDIMENSION) jround_up((long) cinfo->output_width,
 				(long) cinfo->max_h_samp_factor),
 	 (JDIMENSION) cinfo->max_v_samp_factor);
     }
   }
 }

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media/libjpeg/jdsample.c@b8a032363ba2 (annotated)

media/libjpeg/jdsample.c