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Diffstat (limited to 'jpeg/jdsample.c')
| -rw-r--r-- | jpeg/jdsample.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/jpeg/jdsample.c b/jpeg/jdsample.c new file mode 100644 index 0000000..7bc8885 --- /dev/null +++ b/jpeg/jdsample.c @@ -0,0 +1,361 @@ +/* + * jdsample.c + * + * Copyright (C) 1991-1996, Thomas G. Lane. + * Modified 2002-2008 by Guido Vollbeding. + * This file is part of the Independent JPEG Group's software. + * 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_v_scaled_size / min_DCT_v_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" + + +/* 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 outrow; + + for (outrow = 0; outrow < cinfo->max_v_samp_factor; outrow++) { + inptr = input_data[outrow]; + outptr = output_data[outrow]; + 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; + } +} + + +/* + * 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; + 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); + + /* 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_h_scaled_size) / + cinfo->min_DCT_h_scaled_size; + v_in_group = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) / + cinfo->min_DCT_v_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 case for 2h1v upsampling */ + upsample->methods[ci] = h2v1_upsample; + } else if (h_in_group * 2 == h_out_group && + v_in_group * 2 == v_out_group) { + /* Special case for 2h2v upsampling */ + 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); + } + } +} |