jdsample.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "mrpt_jpeglib.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, 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, jpeg_component_info*, 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, jpeg_component_info*, JSAMPARRAY,
        JSAMPARRAY* output_data_ptr)
{
        *output_data_ptr = nullptr; /* 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;
        JSAMPROW inptr, outptr;
        JSAMPLE invalue;
        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*, JSAMPARRAY input_data,
        JSAMPARRAY* output_data_ptr)
{
        JSAMPARRAY output_data = *output_data_ptr;
        JSAMPROW inptr, outptr;
        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*, JSAMPARRAY input_data,
        JSAMPARRAY* output_data_ptr)
{
        JSAMPARRAY output_data = *output_data_ptr;
        JSAMPROW inptr, outptr;
        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;
        JSAMPROW inptr, outptr;
        int invalue;
        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;
        JSAMPROW inptr0, inptr1, outptr;
#if BITS_IN_JSAMPLE == 8
        int thiscolsum, lastcolsum, nextcolsum;
#else
        INT32 thiscolsum, lastcolsum, nextcolsum;
#endif
        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)
                                upsample->methods[ci] = h2v1_fancy_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)
                        {
                                upsample->methods[ci] = h2v2_fancy_upsample;
                                upsample->pub.need_context_rows = TRUE;
                        }
                        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);
                }
        }
}