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 /*

  * 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,

 		      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);

     }

   }

 }