jp2_dec.c

用C语言实现的JPEG编码

	}

	/* A COLR box must be present. */
	if (!dec->colr) {
		jas_eprintf("error: no COLR box\n");
		goto error;
	}

	switch (dec->colr->data.colr.method) {
	case JP2_COLR_ENUM:
		jas_image_setclrspc(dec->image, jp2_getcs(&dec->colr->data.colr));
		break;
	case JP2_COLR_ICC:
		iccprof = jas_iccprof_createfrombuf(dec->colr->data.colr.iccp,
		  dec->colr->data.colr.iccplen);
		assert(iccprof);
		jas_iccprof_gethdr(iccprof, &icchdr);
		jas_eprintf("ICC Profile CS %08x\n", icchdr.colorspc);
		jas_image_setclrspc(dec->image, fromiccpcs(icchdr.colorspc));
		dec->image->cmprof_ = jas_cmprof_createfromiccprof(iccprof);
		assert(dec->image->cmprof_);
		jas_iccprof_destroy(iccprof);
		break;
	}

	/* If a CMAP box is present, a PCLR box must also be present. */
	if (dec->cmap && !dec->pclr) {
		jas_eprintf("warning: missing PCLR box or superfluous CMAP box\n");
		jp2_box_destroy(dec->cmap);
		dec->cmap = 0;
	}

	/* If a CMAP box is not present, a PCLR box must not be present. */
	if (!dec->cmap && dec->pclr) {
		jas_eprintf("warning: missing CMAP box or superfluous PCLR box\n");
		jp2_box_destroy(dec->pclr);
		dec->pclr = 0;
	}

	/* Determine the number of channels (which is essentially the number
	  of components after any palette mappings have been applied). */
	dec->numchans = dec->cmap ? dec->cmap->data.cmap.numchans : JAS_CAST(uint, jas_image_numcmpts(dec->image));

	/* Perform a basic sanity check on the CMAP box if present. */
	if (dec->cmap) {
		for (i = 0; i < dec->numchans; ++i) {
			/* Is the component number reasonable? */
			if (dec->cmap->data.cmap.ents[i].cmptno >= JAS_CAST(uint, jas_image_numcmpts(dec->image))) {
				jas_eprintf("error: invalid component number in CMAP box\n");
				goto error;
			}
			/* Is the LUT index reasonable? */
			if (dec->cmap->data.cmap.ents[i].pcol >= dec->pclr->data.pclr.numchans) {
				jas_eprintf("error: invalid CMAP LUT index\n");
				goto error;
			}
		}
	}

	/* Allocate space for the channel-number to component-number LUT. */
	if (!(dec->chantocmptlut = jas_malloc(dec->numchans * sizeof(uint_fast16_t)))) {
		jas_eprintf("error: no memory\n");
		goto error;
	}

	if (!dec->cmap) {
		for (i = 0; i < dec->numchans; ++i) {
			dec->chantocmptlut[i] = i;
		}
	} else {
		cmapd = &dec->cmap->data.cmap;
		pclrd = &dec->pclr->data.pclr;
		cdefd = &dec->cdef->data.cdef;
		for (channo = 0; channo < cmapd->numchans; ++channo) {
			cmapent = &cmapd->ents[channo];
			if (cmapent->map == JP2_CMAP_DIRECT) {
				dec->chantocmptlut[channo] = channo;
			} else if (cmapent->map == JP2_CMAP_PALETTE) {
				lutents = jas_malloc(pclrd->numlutents * sizeof(int_fast32_t));
				for (i = 0; i < pclrd->numlutents; ++i) {
					lutents[i] = pclrd->lutdata[cmapent->pcol + i * pclrd->numchans];
				}
				newcmptno = jas_image_numcmpts(dec->image);
				jas_image_depalettize(dec->image, cmapent->cmptno, pclrd->numlutents, lutents, JP2_BPCTODTYPE(pclrd->bpc[cmapent->pcol]), newcmptno);
				dec->chantocmptlut[channo] = newcmptno;
				jas_free(lutents);
#if 0
				if (dec->cdef) {
					cdefent = jp2_cdef_lookup(cdefd, channo);
					if (!cdefent) {
						abort();
					}
				jas_image_setcmpttype(dec->image, newcmptno, jp2_getct(jas_image_clrspc(dec->image), cdefent->type, cdefent->assoc));
				} else {
				jas_image_setcmpttype(dec->image, newcmptno, jp2_getct(jas_image_clrspc(dec->image), 0, channo + 1));
				}
#endif
			}
		}
	}

	/* Mark all components as being of unknown type. */

	for (i = 0; i < JAS_CAST(uint, jas_image_numcmpts(dec->image)); ++i) {
		jas_image_setcmpttype(dec->image, i, JAS_IMAGE_CT_UNKNOWN);
	}

	/* Determine the type of each component. */
	if (dec->cdef) {
		for (i = 0; i < dec->numchans; ++i) {
			jas_image_setcmpttype(dec->image,
			  dec->chantocmptlut[dec->cdef->data.cdef.ents[i].channo],
			  jp2_getct(jas_image_clrspc(dec->image),
			  dec->cdef->data.cdef.ents[i].type, dec->cdef->data.cdef.ents[i].assoc));
		}
	} else {
		for (i = 0; i < dec->numchans; ++i) {
			jas_image_setcmpttype(dec->image, dec->chantocmptlut[i],
			  jp2_getct(jas_image_clrspc(dec->image), 0, i + 1));
		}
	}

	/* Delete any components that are not of interest. */
	for (i = jas_image_numcmpts(dec->image); i > 0; --i) {
		if (jas_image_cmpttype(dec->image, i - 1) == JAS_IMAGE_CT_UNKNOWN) {
			jas_image_delcmpt(dec->image, i - 1);
		}
	}

	/* Ensure that some components survived. */
	if (!jas_image_numcmpts(dec->image)) {
		jas_eprintf("error: no components\n");
		goto error;
	}
#if 0
fprintf(stderr, "no of components is %d\n", jas_image_numcmpts(dec->image));
#endif

	/* Prevent the image from being destroyed later. */
	image = dec->image;
	dec->image = 0;

	jp2_dec_destroy(dec);

	return image;

error:
	if (box) {
		jp2_box_destroy(box);
	}
	if (dec) {
		jp2_dec_destroy(dec);
	}
	return 0;
}

int jp2_validate(jas_stream_t *in)
{
	char buf[JP2_VALIDATELEN];
	int i;
	int n;
#if 0
	jas_stream_t *tmpstream;
	jp2_box_t *box;
#endif

	assert(JAS_STREAM_MAXPUTBACK >= JP2_VALIDATELEN);

	/* Read the validation data (i.e., the data used for detecting
	  the format). */
	if ((n = jas_stream_read(in, buf, JP2_VALIDATELEN)) < 0) {
		return -1;
	}

	/* Put the validation data back onto the stream, so that the
	  stream position will not be changed. */
	for (i = n - 1; i >= 0; --i) {
		if (jas_stream_ungetc(in, buf[i]) == EOF) {
			return -1;
		}
	}

	/* Did we read enough data? */
	if (n < JP2_VALIDATELEN) {
		return -1;
	}

	/* Is the box type correct? */
	if (((buf[4] << 24) | (buf[5] << 16) | (buf[6] << 8) | buf[7]) !=
	  JP2_BOX_JP)
	{
		return -1;
	}

	return 0;
}

static jp2_dec_t *jp2_dec_create(void)
{
	jp2_dec_t *dec;

	if (!(dec = jas_malloc(sizeof(jp2_dec_t)))) {
		return 0;
	}
	dec->ihdr = 0;
	dec->bpcc = 0;
	dec->cdef = 0;
	dec->pclr = 0;
	dec->image = 0;
	dec->chantocmptlut = 0;
	dec->cmap = 0;
	dec->colr = 0;
	return dec;
}

static void jp2_dec_destroy(jp2_dec_t *dec)
{
	if (dec->ihdr) {
		jp2_box_destroy(dec->ihdr);
	}
	if (dec->bpcc) {
		jp2_box_destroy(dec->bpcc);
	}
	if (dec->cdef) {
		jp2_box_destroy(dec->cdef);
	}
	if (dec->pclr) {
		jp2_box_destroy(dec->pclr);
	}
	if (dec->image) {
		jas_image_destroy(dec->image);
	}
	if (dec->cmap) {
		jp2_box_destroy(dec->cmap);
	}
	if (dec->colr) {
		jp2_box_destroy(dec->colr);
	}
	if (dec->chantocmptlut) {
		jas_free(dec->chantocmptlut);
	}
	jas_free(dec);
}

static int jp2_getct(int colorspace, int type, int assoc)
{
	if (type == 1 && assoc == 0) {
		return JAS_IMAGE_CT_OPACITY;
	}
	if (type == 0 && assoc >= 1 && assoc <= 65534) {
		switch (colorspace) {
		case JAS_CLRSPC_FAM_RGB:
			switch (assoc) {
			case JP2_CDEF_RGB_R:
				return JAS_IMAGE_CT_COLOR(JAS_CLRSPC_CHANIND_RGB_R);
				break;
			case JP2_CDEF_RGB_G:
				return JAS_IMAGE_CT_COLOR(JAS_CLRSPC_CHANIND_RGB_G);
				break;
			case JP2_CDEF_RGB_B:
				return JAS_IMAGE_CT_COLOR(JAS_CLRSPC_CHANIND_RGB_B);
				break;
			}
			break;
		case JAS_CLRSPC_FAM_YCBCR:
			switch (assoc) {
			case JP2_CDEF_YCBCR_Y:
				return JAS_IMAGE_CT_COLOR(JAS_CLRSPC_CHANIND_YCBCR_Y);
				break;
			case JP2_CDEF_YCBCR_CB:
				return JAS_IMAGE_CT_COLOR(JAS_CLRSPC_CHANIND_YCBCR_CB);
				break;
			case JP2_CDEF_YCBCR_CR:
				return JAS_IMAGE_CT_COLOR(JAS_CLRSPC_CHANIND_YCBCR_CR);
				break;
			}
			break;
		case JAS_CLRSPC_FAM_GRAY:
			switch (assoc) {
			case JP2_CDEF_GRAY_Y:
				return JAS_IMAGE_CT_COLOR(JAS_CLRSPC_CHANIND_GRAY_Y);
				break;
			}
			break;
		default:
			return JAS_IMAGE_CT_COLOR(assoc - 1);
			break;
		}
	}
	return JAS_IMAGE_CT_UNKNOWN;
}

static int jp2_getcs(jp2_colr_t *colr)
{
	if (colr->method == JP2_COLR_ENUM) {
		switch (colr->csid) {
		case JP2_COLR_SRGB:
			return JAS_CLRSPC_SRGB;
			break;
		case JP2_COLR_SYCC:
			return JAS_CLRSPC_SYCBCR;
			break;
		case JP2_COLR_SGRAY:
			return JAS_CLRSPC_SGRAY;
			break;
		}
	}
	return JAS_CLRSPC_UNKNOWN;
}

static int fromiccpcs(int cs)
{
	switch (cs) {
	case ICC_CS_RGB:
		return JAS_CLRSPC_GENRGB;
		break;
	case ICC_CS_YCBCR:
		return JAS_CLRSPC_GENYCBCR;
		break;
	case ICC_CS_GRAY:
		return JAS_CLRSPC_GENGRAY;
		break;
	}
	return JAS_CLRSPC_UNKNOWN;
}