jquant2.c

MCB2300_ucgui_LCD320240.rar LPC2368的uc/gui的移植

			/* work right to left in this row */
			inptr += (width - 1) * 3;	/* so point to rightmost pixel */
			outptr += width - 1;
			dir = -1;
			dir3 = -3;
			errorptr = cquantize->fserrors + (width + 1) * 3; /* => entry after last column */
			cquantize->on_odd_row = FALSE; /* flip for next time */
		}
		else
		{
			/* work left to right in this row */
			dir = 1;
			dir3 = 3;
			errorptr = cquantize->fserrors; /* => entry before first real column */
			cquantize->on_odd_row = TRUE; /* flip for next time */
		}
		/* Preset error values: no error propagated to first pixel from left */
		cur0 = cur1 = cur2 = 0;
		/* and no error propagated to row below yet */
		belowerr0 = belowerr1 = belowerr2 = 0;
		bpreverr0 = bpreverr1 = bpreverr2 = 0;

		for (col = width; col > 0; col--)
		{
			/* curN holds the error propagated from the previous pixel on the
			 * current line.  Add the error propagated from the previous line
			 * to form the complete error correction term for this pixel, and
			 * round the error term (which is expressed * 16) to an integer.
			 * RIGHT_SHIFT rounds towards minus infinity, so adding 8 is correct
			 * for either sign of the error value.
			 * Note: errorptr points to *previous* column's array entry.
			 */
			cur0 = RIGHT_SHIFT(cur0 + errorptr[dir3 + 0] + 8, 4);
			cur1 = RIGHT_SHIFT(cur1 + errorptr[dir3 + 1] + 8, 4);
			cur2 = RIGHT_SHIFT(cur2 + errorptr[dir3 + 2] + 8, 4);
			/* Limit the error using transfer function set by init_error_limit.
			 * See comments with init_error_limit for rationale.
			 */
			cur0 = error_limit[cur0];
			cur1 = error_limit[cur1];
			cur2 = error_limit[cur2];
			/* Form pixel value + error, and range-limit to 0..MAXJSAMPLE.
			 * The maximum error is +- MAXJSAMPLE (or less with error limiting);
			 * this sets the required size of the range_limit array.
			 */
			cur0 += GETJSAMPLE(inptr[0]);
			cur1 += GETJSAMPLE(inptr[1]);
			cur2 += GETJSAMPLE(inptr[2]);
			cur0 = GETJSAMPLE(range_limit[cur0]);
			cur1 = GETJSAMPLE(range_limit[cur1]);
			cur2 = GETJSAMPLE(range_limit[cur2]);
			/* Index into the cache with adjusted pixel value */
			cachep = &histogram[cur0 >> C0_SHIFT][cur1 >> C1_SHIFT][cur2 >> C2_SHIFT];
			/* If we have not seen this color before, find nearest colormap */
			/* entry and update the cache */
			if (*cachep == 0)
			{
				fill_inverse_cmap(cinfo, cur0 >> C0_SHIFT, cur1 >> C1_SHIFT, cur2 >> C2_SHIFT);
			}
			/* Now emit the colormap index for this cell */
			{
				register int pixcode = *cachep - 1;
				*outptr = (JSAMPLE) pixcode;
				/* Compute representation error for this pixel */
				cur0 -= GETJSAMPLE(colormap0[pixcode]);
				cur1 -= GETJSAMPLE(colormap1[pixcode]);
				cur2 -= GETJSAMPLE(colormap2[pixcode]);
			}
			/* Compute error fractions to be propagated to adjacent pixels.
			 * Add these into the running sums, and simultaneously shift the
			 * next-line error sums left by 1 column.
			 */
			{
				register LOCFSERROR bnexterr, delta;

				bnexterr = cur0;	/* Process component 0 */
				delta = cur0 * 2;
				cur0 += delta;		/* form error * 3 */
				errorptr[0] = (FSERROR) (bpreverr0 + cur0);
				cur0 += delta;		/* form error * 5 */
				bpreverr0 = belowerr0 + cur0;
				belowerr0 = bnexterr;
				cur0 += delta;		/* form error * 7 */
				bnexterr = cur1;	/* Process component 1 */
				delta = cur1 * 2;
				cur1 += delta;		/* form error * 3 */
				errorptr[1] = (FSERROR) (bpreverr1 + cur1);
				cur1 += delta;		/* form error * 5 */
				bpreverr1 = belowerr1 + cur1;
				belowerr1 = bnexterr;
				cur1 += delta;		/* form error * 7 */
				bnexterr = cur2;	/* Process component 2 */
				delta = cur2 * 2;
				cur2 += delta;		/* form error * 3 */
				errorptr[2] = (FSERROR) (bpreverr2 + cur2);
				cur2 += delta;		/* form error * 5 */
				bpreverr2 = belowerr2 + cur2;
				belowerr2 = bnexterr;
				cur2 += delta;		/* form error * 7 */
			}
			/* At this point curN contains the 7/16 error value to be propagated
			 * to the next pixel on the current line, and all the errors for the
			 * next line have been shifted over.  We are therefore ready to move on.
			 */
			inptr += dir3;		/* Advance pixel pointers to next column */
			outptr += dir;
			errorptr += dir3;		/* advance errorptr to current column */
		}
		/* Post-loop cleanup: we must unload the final error values into the
		 * final fserrors[] entry.  Note we need not unload belowerrN because
		 * it is for the dummy column before or after the actual array.
		 */
		errorptr[0] = (FSERROR) bpreverr0; /* unload prev errs into array */
		errorptr[1] = (FSERROR) bpreverr1;
		errorptr[2] = (FSERROR) bpreverr2;
	}
}


/*
 * Initialize the error-limiting transfer function (lookup table).
 * The raw F-S error computation can potentially compute error values of up to
 * +- MAXJSAMPLE.  But we want the maximum correction applied to a pixel to be
 * much less, otherwise obviously wrong pixels will be created.  (Typical
 * effects include weird fringes at color-area boundaries, isolated bright
 * pixels in a dark area, etc.)  The standard advice for avoiding this problem
 * is to ensure that the "corners" of the color cube are allocated as output
 * colors; then repeated errors in the same direction cannot cause cascading
 * error buildup.  However, that only prevents the error from getting
 * completely out of hand; Aaron Giles reports that error limiting improves
 * the results even with corner colors allocated.
 * A simple clamping of the error values to about +- MAXJSAMPLE/8 works pretty
 * well, but the smoother transfer function used below is even better.  Thanks
 * to Aaron Giles for this idea.
 */

LOCAL(void)
init_error_limit(j_decompress_ptr cinfo)
/* Allocate and fill in the error_limiter table */
{
	my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
	int * table;
	int in, out;

	table = (int *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE * 2 + 1) * SIZEOF(int));
	table += MAXJSAMPLE;		/* so can index -MAXJSAMPLE .. +MAXJSAMPLE */
	cquantize->error_limiter = table;

#define STEPSIZE ((MAXJSAMPLE+1)/16)
	/* Map errors 1:1 up to +- MAXJSAMPLE/16 */
	out = 0;
	for (in = 0; in < STEPSIZE; in++, out++)
	{
		table[in] = out; table[-in] = -out;
	}
	/* Map errors 1:2 up to +- 3*MAXJSAMPLE/16 */
	for (; in < STEPSIZE*3; in++, out += (in&1) ? 0 : 1)
	{
		table[in] = out; table[-in] = -out;
	}
	/* Clamp the rest to final out value (which is (MAXJSAMPLE+1)/8) */
	for (; in <= MAXJSAMPLE; in++)
	{
		table[in] = out; table[-in] = -out;
	}
#undef STEPSIZE
}


/*
 * Finish up at the end of each pass.
 */

METHODDEF(void)
finish_pass1(j_decompress_ptr cinfo)
{
	my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

	/* Select the representative colors and fill in cinfo->colormap */
	cinfo->colormap = cquantize->sv_colormap;
	select_colors(cinfo, cquantize->desired);
	/* Force next pass to zero the color index table */
	cquantize->needs_zeroed = TRUE;
}


METHODDEF(void)
finish_pass2(j_decompress_ptr cinfo)
{
	GUI_USE_PARA(cinfo);
	/* no work */
}


/*
 * Initialize for each processing pass.
 */

METHODDEF(void)
start_pass_2_quant(j_decompress_ptr cinfo, boolean is_pre_scan)
{
	my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
	hist3d histogram = cquantize->histogram;
	int i;

	/* Only F-S dithering or no dithering is supported. */
	/* If user asks for ordered dither, give him F-S. */
	if (cinfo->dither_mode != JDITHER_NONE)
	{
		cinfo->dither_mode = JDITHER_FS;
	}

	if (is_pre_scan)
	{
		/* Set up method pointers */
		cquantize->pub.color_quantize = prescan_quantize;
		cquantize->pub.finish_pass = finish_pass1;
		cquantize->needs_zeroed = TRUE; /* Always zero histogram */
	}
	else
	{
		/* Set up method pointers */
		if (cinfo->dither_mode == JDITHER_FS)
		{
			cquantize->pub.color_quantize = pass2_fs_dither;
		}
		else
		{
			cquantize->pub.color_quantize = pass2_no_dither;
		}
		cquantize->pub.finish_pass = finish_pass2;

		/* Make sure color count is acceptable */
		i = cinfo->actual_number_of_colors;
		if (i < 1)
		{
			ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, 1);
		}
		if (i > MAXNUMCOLORS)
		{
			ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXNUMCOLORS);
		}

		if (cinfo->dither_mode == JDITHER_FS)
		{
			size_t arraysize = (size_t) ((cinfo->output_width + 2) * (3 * SIZEOF(FSERROR)));
			/* Allocate Floyd-Steinberg workspace if we didn't already. */
			if (cquantize->fserrors == NULL)
			{
				cquantize->fserrors = (FSERRPTR) (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, arraysize);
			}
			/* Initialize the propagated errors to zero. */
			jzero_far((void FAR *) cquantize->fserrors, arraysize);
			/* Make the error-limit table if we didn't already. */
			if (cquantize->error_limiter == NULL)
			{
				init_error_limit(cinfo);
			}
			cquantize->on_odd_row = FALSE;
		}
	}
	/* Zero the histogram or inverse color map, if necessary */
	if (cquantize->needs_zeroed)
	{
		for (i = 0; i < HIST_C0_ELEMS; i++)
		{
			jzero_far((void FAR *) histogram[i], HIST_C1_ELEMS * HIST_C2_ELEMS * SIZEOF(histcell));
		}
		cquantize->needs_zeroed = FALSE;
	}
}


/*
 * Switch to a new external colormap between output passes.
 */

METHODDEF(void)
new_color_map_2_quant(j_decompress_ptr cinfo)
{
	my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

	/* Reset the inverse color map */
	cquantize->needs_zeroed = TRUE;
}


/*
 * Module initialization routine for 2-pass color quantization.
 */

GLOBAL(void)
jinit_2pass_quantizer(j_decompress_ptr cinfo)
{
	my_cquantize_ptr cquantize;
	int i;

	cquantize = (my_cquantize_ptr) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_cquantizer));
	cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize;
	cquantize->pub.start_pass = start_pass_2_quant;
	cquantize->pub.new_color_map = new_color_map_2_quant;
	cquantize->fserrors = NULL;	/* flag optional arrays not allocated */
	cquantize->error_limiter = NULL;

	/* Make sure jdmaster didn't give me a case I can't handle */
	if (cinfo->out_color_components != 3)
	{
		ERREXIT(cinfo, JERR_NOTIMPL);
	}

	/* Allocate the histogram/inverse colormap storage */
	cquantize->histogram = (hist3d) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, HIST_C0_ELEMS * SIZEOF(hist2d));
	for (i = 0; i < HIST_C0_ELEMS; i++)
	{
		cquantize->histogram[i] = (hist2d) (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, HIST_C1_ELEMS * HIST_C2_ELEMS * SIZEOF(histcell));
	}
	cquantize->needs_zeroed = TRUE; /* histogram is garbage now */

	/* Allocate storage for the completed colormap, if required.
	 * We do this now since it is FAR storage and may affect
	 * the memory manager's space calculations.
	 */
	if (cinfo->enable_2pass_quant)
	{
		/* Make sure color count is acceptable */
		int desired = cinfo->desired_number_of_colors;
		/* Lower bound on # of colors ... somewhat arbitrary as long as > 0 */
		if (desired < 8)
		{
			ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, 8);
		}
		/* Make sure colormap indexes can be represented by JSAMPLEs */
		if (desired > MAXNUMCOLORS)
		{
			ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXNUMCOLORS);
		}
		cquantize->sv_colormap = (*cinfo->mem->alloc_sarray) ((j_common_ptr) cinfo, JPOOL_IMAGE, (JDIMENSION) desired, (JDIMENSION) 3);
		cquantize->desired = desired;
	}
	else
	{
		cquantize->sv_colormap = NULL;
	}

	/* Only F-S dithering or no dithering is supported. */
	/* If user asks for ordered dither, give him F-S. */
	if (cinfo->dither_mode != JDITHER_NONE)
	{
		cinfo->dither_mode = JDITHER_FS;
	}

	/* Allocate Floyd-Steinberg workspace if necessary.
	 * This isn't really needed until pass 2, but again it is FAR storage.
	 * Although we will cope with a later change in dither_mode,
	 * we do not promise to honor max_memory_to_use if dither_mode changes.
	 */
	if (cinfo->dither_mode == JDITHER_FS)
	{
		cquantize->fserrors = (FSERRPTR) (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, (size_t) ((cinfo->output_width + 2) * (3 * SIZEOF(FSERROR))));
		/* Might as well create the error-limiting table too. */
		init_error_limit(cinfo);
	}
}

#endif /* QUANT_2PASS_SUPPORTED */