jdsample.c

MCB2300_ucgui_LCD320240.rar LPC2368的uc/gui的移植

			*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;

	GUI_USE_PARA(compptr);
	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)
			{
				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);
		}
	}
}