tif_pixarlog.c

一个国人自己实现图像库的程序（有参考价值）

	} else {
	    REPEAT(stride, *op = ToLinear8[*wp&mask]; wp++; op++)
	    n -= stride;
	    while (n > 0) {
		REPEAT(stride,
		    wp[stride] += *wp; *op = ToLinear8[*wp&mask]; wp++; op++)
		n -= stride;
	    }
	}
    }
}

/*
 * State block for each open TIFF
 * file using PixarLog compression/decompression.
 */
typedef	struct {
	TIFFPredictorState	predict;
	z_stream		stream;
	uint16			*tbuf; 
	uint16			stride;
	int			state;
	int			user_datafmt;
	int			quality;
#define PLSTATE_INIT 1

	TIFFVSetMethod		vgetparent;	/* super-class method */
	TIFFVSetMethod		vsetparent;	/* super-class method */

	float *ToLinearF;
	uint16 *ToLinear16;
	unsigned char *ToLinear8;
	uint16  *FromLT2;
	uint16  *From14; /* Really for 16-bit data, but we shift down 2 */
	uint16  *From8;
	
} PixarLogState;

static int
PixarLogMakeTables(PixarLogState *sp)
{

/*
 *    We make several tables here to convert between various external
 *    representations (float, 16-bit, and 8-bit) and the internal
 *    11-bit companded representation.  The 11-bit representation has two
 *    distinct regions.  A linear bottom end up through .018316 in steps
 *    of about .000073, and a region of constant ratio up to about 25.
 *    These floating point numbers are stored in the main table ToLinearF. 
 *    All other tables are derived from this one.  The tables (and the
 *    ratios) are continuous at the internal seam.
 */

    int  nlin, lt2size;
    int  i, j;
    double  b, c, linstep, max;
    double  k, v, dv, r, lr2, r2;
    float *ToLinearF;
    uint16 *ToLinear16;
    unsigned char *ToLinear8;
    uint16  *FromLT2;
    uint16  *From14; /* Really for 16-bit data, but we shift down 2 */
    uint16  *From8;

    c = log(RATIO);	
    nlin = 1./c;	/* nlin must be an integer */
    c = 1./nlin;
    b = exp(-c*ONE);	/* multiplicative scale factor [b*exp(c*ONE) = 1] */
    linstep = b*c*exp(1.);

    LogK1 = 1./c;	/* if (v >= 2)  token = k1*log(v*k2) */
    LogK2 = 1./b;
    lt2size = (2./linstep)+1;
    FromLT2 = (uint16 *)_TIFFmalloc(lt2size*sizeof(uint16));
    From14 = (uint16 *)_TIFFmalloc(16384*sizeof(uint16));
    From8 = (uint16 *)_TIFFmalloc(256*sizeof(uint16));
    ToLinearF = (float *)_TIFFmalloc(TSIZEP1 * sizeof(float));
    ToLinear16 = (uint16 *)_TIFFmalloc(TSIZEP1 * sizeof(uint16));
    ToLinear8 = (unsigned char *)_TIFFmalloc(TSIZEP1 * sizeof(unsigned char));
    if (FromLT2 == NULL || From14  == NULL || From8   == NULL ||
	 ToLinearF == NULL || ToLinear16 == NULL || ToLinear8 == NULL) {
	if (FromLT2) _TIFFfree(FromLT2);
	if (From14) _TIFFfree(From14);
	if (From8) _TIFFfree(From8);
	if (ToLinearF) _TIFFfree(ToLinearF);
	if (ToLinear16) _TIFFfree(ToLinear16);
	if (ToLinear8) _TIFFfree(ToLinear8);
	sp->FromLT2 = NULL;
	sp->From14 = NULL;
	sp->From8 = NULL;
	sp->ToLinearF = NULL;
	sp->ToLinear16 = NULL;
	sp->ToLinear8 = NULL;
	return 0;
    }

    j = 0;

    for (i = 0; i < nlin; i++)  {
	v = i * linstep;
	ToLinearF[j++] = v;
    }

    for (i = nlin; i < TSIZE; i++)
	ToLinearF[j++] = b*exp(c*i);

    ToLinearF[2048] = ToLinearF[2047];

    for (i = 0; i < TSIZEP1; i++)  {
	v = ToLinearF[i]*65535.0 + 0.5;
	ToLinear16[i] = (v > 65535.0) ? 65535 : v;
	v = ToLinearF[i]*255.0  + 0.5;
	ToLinear8[i]  = (v > 255.0) ? 255 : v;
    }

    j = 0;
    for (i = 0; i < lt2size; i++)  {
	if ((i*linstep)*(i*linstep) > ToLinearF[j]*ToLinearF[j+1])
	    j++;
	FromLT2[i] = j;
    }

    /*
     * Since we lose info anyway on 16-bit data, we set up a 14-bit
     * table and shift 16-bit values down two bits on input.
     * saves a little table space.
     */
    j = 0;
    for (i = 0; i < 16384; i++)  {
	while ((i/16383.)*(i/16383.) > ToLinearF[j]*ToLinearF[j+1])
	    j++;
	From14[i] = j;
    }

    j = 0;
    for (i = 0; i < 256; i++)  {
	while ((i/255.)*(i/255.) > ToLinearF[j]*ToLinearF[j+1])
	    j++;
	From8[i] = j;
    }

    Fltsize = lt2size/2;

    sp->ToLinearF = ToLinearF;
    sp->ToLinear16 = ToLinear16;
    sp->ToLinear8 = ToLinear8;
    sp->FromLT2 = FromLT2;
    sp->From14 = From14;
    sp->From8 = From8;

    return 1;
}

#define	DecoderState(tif)	((PixarLogState*) (tif)->tif_data)
#define	EncoderState(tif)	((PixarLogState*) (tif)->tif_data)

static	int PixarLogEncode(TIFF*, tidata_t, tsize_t, tsample_t);
static	int PixarLogDecode(TIFF*, tidata_t, tsize_t, tsample_t);

#define N(a)   (sizeof(a)/sizeof(a[0]))
#define PIXARLOGDATAFMT_UNKNOWN	-1

static int
PixarLogGuessDataFmt(TIFFDirectory *td)
{
	int guess = PIXARLOGDATAFMT_UNKNOWN;
	int format = td->td_sampleformat;

	/* If the user didn't tell us his datafmt,
	 * take our best guess from the bitspersample.
	 */
	switch (td->td_bitspersample) {
	 case 32:
		if (format == SAMPLEFORMAT_IEEEFP)
			guess = PIXARLOGDATAFMT_FLOAT;
		break;
	 case 16:
		if (format == SAMPLEFORMAT_VOID || format == SAMPLEFORMAT_UINT)
			guess = PIXARLOGDATAFMT_16BIT;
		break;
	 case 12:
		if (format == SAMPLEFORMAT_VOID || format == SAMPLEFORMAT_INT)
			guess = PIXARLOGDATAFMT_12BITPICIO;
		break;
	 case 11:
		if (format == SAMPLEFORMAT_VOID || format == SAMPLEFORMAT_UINT)
			guess = PIXARLOGDATAFMT_11BITLOG;
		break;
	 case 8:
		if (format == SAMPLEFORMAT_VOID || format == SAMPLEFORMAT_UINT)
			guess = PIXARLOGDATAFMT_8BIT;
		break;
	}

	return guess;
}

static int
PixarLogSetupDecode(TIFF* tif)
{
	TIFFDirectory *td = &tif->tif_dir;
	PixarLogState* sp = DecoderState(tif);
	static const char module[] = "PixarLogSetupDecode";

	assert(sp != NULL);

	/* Make sure no byte swapping happens on the data
	 * after decompression. */
	tif->tif_postdecode = _TIFFNoPostDecode;

	/* for some reason, we can't do this in TIFFInitPixarLog */

	sp->stride = (td->td_planarconfig == PLANARCONFIG_CONTIG ?
	    td->td_samplesperpixel : 1);
	sp->tbuf = (uint16 *) _TIFFmalloc(sp->stride * 
		td->td_imagewidth * td->td_rowsperstrip * sizeof(uint16));
	if (sp->user_datafmt == PIXARLOGDATAFMT_UNKNOWN)
		sp->user_datafmt = PixarLogGuessDataFmt(td);
	if (sp->user_datafmt == PIXARLOGDATAFMT_UNKNOWN) {
		TIFFError(module, 
			"PixarLog compression can't handle bits depth/data format combination (depth: %d)", 
			td->td_bitspersample);
		return (0);
	}

	if (inflateInit(&sp->stream) != Z_OK) {
		TIFFError(module, "%s: %s", tif->tif_name, sp->stream.msg);
		return (0);
	} else {
		sp->state |= PLSTATE_INIT;
		return (1);
	}
}

/*
 * Setup state for decoding a strip.
 */
static int
PixarLogPreDecode(TIFF* tif, tsample_t s)
{
	TIFFDirectory *td = &tif->tif_dir;
	PixarLogState* sp = DecoderState(tif);

	(void) s;
	assert(sp != NULL);
	sp->stream.next_in = tif->tif_rawdata;
	sp->stream.avail_in = tif->tif_rawcc;
	return (inflateReset(&sp->stream) == Z_OK);
}

static int
PixarLogDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
{
	TIFFDirectory *td = &tif->tif_dir;
	PixarLogState* sp = DecoderState(tif);
	static const char module[] = "PixarLogDecode";
	int i, nsamples, llen;
	uint16 *up;

	switch (sp->user_datafmt) {
	case PIXARLOGDATAFMT_FLOAT:
		nsamples = occ / sizeof(float);	/* XXX float == 32 bits */
		break;
	case PIXARLOGDATAFMT_16BIT:
	case PIXARLOGDATAFMT_12BITPICIO:
	case PIXARLOGDATAFMT_11BITLOG:
		nsamples = occ / sizeof(uint16); /* XXX uint16 == 16 bits */
		break;
	case PIXARLOGDATAFMT_8BIT:
	case PIXARLOGDATAFMT_8BITABGR:
		nsamples = occ;
		break;
	default:
		TIFFError(tif->tif_name,
			"%d bit input not supported in PixarLog",
			td->td_bitspersample);
		return 0;
	}

	llen = sp->stride * td->td_imagewidth;

	(void) s;
	assert(sp != NULL);
	sp->stream.next_out = (unsigned char *) sp->tbuf;
	sp->stream.avail_out = nsamples * sizeof(uint16);
	do {
		int state = inflate(&sp->stream, Z_PARTIAL_FLUSH);
		if (state == Z_STREAM_END) {
			break;			/* XXX */
		}
		if (state == Z_DATA_ERROR) {
			TIFFError(module,
			    "%s: Decoding error at scanline %d, %s",
			    tif->tif_name, tif->tif_row, sp->stream.msg);
			if (inflateSync(&sp->stream) != Z_OK)
				return (0);
			continue;
		}
		if (state != Z_OK) {
			TIFFError(module, "%s: zlib error: %s",
			    tif->tif_name, sp->stream.msg);
			return (0);
		}
	} while (sp->stream.avail_out > 0);

	/* hopefully, we got all the bytes we needed */
	if (sp->stream.avail_out != 0) {
		TIFFError(module,
		    "%s: Not enough data at scanline %d (short %d bytes)",
		    tif->tif_name, tif->tif_row, sp->stream.avail_out);
		return (0);
	}

	up = sp->tbuf;
	/* Swap bytes in the data if from a different endian machine. */
	if (tif->tif_flags & TIFF_SWAB)
		TIFFSwabArrayOfShort(up, nsamples);

	for (i = 0; i < nsamples; i += llen, up += llen) {
		switch (sp->user_datafmt)  {
		case PIXARLOGDATAFMT_FLOAT:
			horizontalAccumulateF(up, llen, sp->stride,
					(float *)op, sp->ToLinearF);
			op += llen * sizeof(float);
			break;
		case PIXARLOGDATAFMT_16BIT:
			horizontalAccumulate16(up, llen, sp->stride,
					(uint16 *)op, sp->ToLinear16);
			op += llen * sizeof(uint16);
			break;
		case PIXARLOGDATAFMT_12BITPICIO:
			horizontalAccumulate12(up, llen, sp->stride,
					(int16 *)op, sp->ToLinearF);
			op += llen * sizeof(int16);
			break;
		case PIXARLOGDATAFMT_11BITLOG:
			horizontalAccumulate11(up, llen, sp->stride,
					(uint16 *)op);
			op += llen * sizeof(uint16);
			break;
		case PIXARLOGDATAFMT_8BIT:
			horizontalAccumulate8(up, llen, sp->stride,
					(unsigned char *)op, sp->ToLinear8);
			op += llen * sizeof(unsigned char);
			break;
		case PIXARLOGDATAFMT_8BITABGR:
			horizontalAccumulate8abgr(up, llen, sp->stride,
					(unsigned char *)op, sp->ToLinear8);
			op += llen * sizeof(unsigned char);
			break;
		default:
			TIFFError(tif->tif_name,
				  "PixarLogDecode: unsupported bits/sample: %d", 
				  td->td_bitspersample);
			return (0);
		}
	}

	return (1);
}

static int
PixarLogSetupEncode(TIFF* tif)
{
	TIFFDirectory *td = &tif->tif_dir;
	PixarLogState* sp = EncoderState(tif);
	static const char module[] = "PixarLogSetupEncode";

	assert(sp != NULL);

	/* for some reason, we can't do this in TIFFInitPixarLog */

	sp->stride = (td->td_planarconfig == PLANARCONFIG_CONTIG ?
	    td->td_samplesperpixel : 1);
	sp->tbuf = (uint16 *) _TIFFmalloc(sp->stride * 
		td->td_imagewidth * td->td_rowsperstrip * sizeof(uint16));
	if (sp->user_datafmt == PIXARLOGDATAFMT_UNKNOWN)
		sp->user_datafmt = PixarLogGuessDataFmt(td);
	if (sp->user_datafmt == PIXARLOGDATAFMT_UNKNOWN) {
		TIFFError(module, "PixarLog compression can't handle %d bit linear encodings", td->td_bitspersample);
		return (0);
	}

	if (deflateInit(&sp->stream, sp->quality) != Z_OK) {
		TIFFError(module, "%s: %s", tif->tif_name, sp->stream.msg);
		return (0);
	} else {
		sp->state |= PLSTATE_INIT;
		return (1);
	}
}

/*
 * Reset encoding state at the start of a strip.
 */
static int
PixarLogPreEncode(TIFF* tif, tsample_t s)
{
	TIFFDirectory *td = &tif->tif_dir;
	PixarLogState *sp = EncoderState(tif);

	(void) s;
	assert(sp != NULL);
	sp->stream.next_out = tif->tif_rawdata;
	sp->stream.avail_out = tif->tif_rawdatasize;
	return (deflateReset(&sp->stream) == Z_OK);
}

static void
horizontalDifferenceF(float *ip, int n, int stride, uint16 *wp, uint16 *FromLT2)
{

    register int  r1, g1, b1, a1, r2, g2, b2, a2, mask;
    register float  fltsize = Fltsize;

#define  CLAMP(v) ( (v<(float)0.)   ? 0				\
		  : (v<(float)2.)   ? FromLT2[(int)(v*fltsize)]	\
		  : (v>(float)24.2) ? 2047			\
		  : LogK1*log(v*LogK2) + 0.5 )

    mask = CODE_MASK;
    if (n >= stride) {
	if (stride == 3) {
	    r2 = wp[0] = CLAMP(ip[0]);  g2 = wp[1] = CLAMP(ip[1]);
	    b2 = wp[2] = CLAMP(ip[2]);
	    n -= 3;
	    while (n > 0) {
		n -= 3;
		wp += 3;
		ip += 3;
		r1 = CLAMP(ip[0]); wp[0] = (r1-r2) & mask; r2 = r1;
		g1 = CLAMP(ip[1]); wp[1] = (g1-g2) & mask; g2 = g1;
		b1 = CLAMP(ip[2]); wp[2] = (b1-b2) & mask; b2 = b1;
	    }
	} else if (stride == 4) {
	    r2 = wp[0] = CLAMP(ip[0]);  g2 = wp[1] = CLAMP(ip[1]);
	    b2 = wp[2] = CLAMP(ip[2]);  a2 = wp[3] = CLAMP(ip[3]);