Pillow/src/libImaging/Unpack.c

/*
 * The Python Imaging Library.
 * $Id$
 *
 * code to unpack raw data from various file formats
 *
 * history:
 * 1996-03-07 fl   Created (from various decoders)
 * 1996-04-19 fl   Added band unpackers
 * 1996-05-12 fl   Published RGB unpackers
 * 1996-05-27 fl   Added nibble unpacker
 * 1996-12-10 fl   Added complete set of PNG unpackers
 * 1996-12-29 fl   Set alpha byte in RGB unpackers
 * 1997-01-05 fl   Added remaining TGA unpackers
 * 1997-01-18 fl   Added inverting band unpackers
 * 1997-01-25 fl   Added FlashPix unpackers
 * 1997-05-31 fl   Added floating point unpackers
 * 1998-02-08 fl   Added I unpacker
 * 1998-07-01 fl   Added YCbCr unpacker
 * 1998-07-02 fl   Added full set of integer unpackers
 * 1998-12-29 fl   Added mode field, I;16 unpackers
 * 1998-12-30 fl   Added RGBX modes
 * 1999-02-04 fl   Fixed I;16 unpackers
 * 2003-05-13 fl   Added L/RGB reversed unpackers
 * 2003-09-26 fl   Added LA/PA and RGBa->RGB unpackers
 *
 * Copyright (c) 1997-2003 by Secret Labs AB.
 * Copyright (c) 1996-1997 by Fredrik Lundh.
 *
 * See the README file for information on usage and redistribution.
 */

#include "Imaging.h"

#define R 0
#define G 1
#define B 2
#define X 3

#define A 3

#define C 0
#define M 1
#define Y 2
#define K 3

/* byte-swapping macros */

#define C16N (tmp[0] = in[0], tmp[1] = in[1]);
#define C16S (tmp[1] = in[0], tmp[0] = in[1]);
#define C32N (tmp[0] = in[0], tmp[1] = in[1], tmp[2] = in[2], tmp[3] = in[3]);
#define C32S (tmp[3] = in[0], tmp[2] = in[1], tmp[1] = in[2], tmp[0] = in[3]);
#define C64N         \
    (tmp[0] = in[0], \
     tmp[1] = in[1], \
     tmp[2] = in[2], \
     tmp[3] = in[3], \
     tmp[4] = in[4], \
     tmp[5] = in[5], \
     tmp[6] = in[6], \
     tmp[7] = in[7]);
#define C64S         \
    (tmp[7] = in[0], \
     tmp[6] = in[1], \
     tmp[5] = in[2], \
     tmp[4] = in[3], \
     tmp[3] = in[4], \
     tmp[2] = in[5], \
     tmp[1] = in[6], \
     tmp[0] = in[7]);

#ifdef WORDS_BIGENDIAN
#define C16B C16N
#define C16L C16S
#define C32B C32N
#define C32L C32S
#define C64B C64N
#define C64L C64S
#else
#define C16B C16S
#define C16L C16N
#define C32B C32S
#define C32L C32N
#define C64B C64S
#define C64L C64N
#endif

/* bit-swapping */

static UINT8 BITFLIP[] = {
    0,  128, 64, 192, 32, 160, 96,  224, 16, 144, 80, 208, 48, 176, 112, 240,
    8,  136, 72, 200, 40, 168, 104, 232, 24, 152, 88, 216, 56, 184, 120, 248,
    4,  132, 68, 196, 36, 164, 100, 228, 20, 148, 84, 212, 52, 180, 116, 244,
    12, 140, 76, 204, 44, 172, 108, 236, 28, 156, 92, 220, 60, 188, 124, 252,
    2,  130, 66, 194, 34, 162, 98,  226, 18, 146, 82, 210, 50, 178, 114, 242,
    10, 138, 74, 202, 42, 170, 106, 234, 26, 154, 90, 218, 58, 186, 122, 250,
    6,  134, 70, 198, 38, 166, 102, 230, 22, 150, 86, 214, 54, 182, 118, 246,
    14, 142, 78, 206, 46, 174, 110, 238, 30, 158, 94, 222, 62, 190, 126, 254,
    1,  129, 65, 193, 33, 161, 97,  225, 17, 145, 81, 209, 49, 177, 113, 241,
    9,  137, 73, 201, 41, 169, 105, 233, 25, 153, 89, 217, 57, 185, 121, 249,
    5,  133, 69, 197, 37, 165, 101, 229, 21, 149, 85, 213, 53, 181, 117, 245,
    13, 141, 77, 205, 45, 173, 109, 237, 29, 157, 93, 221, 61, 189, 125, 253,
    3,  131, 67, 195, 35, 163, 99,  227, 19, 147, 83, 211, 51, 179, 115, 243,
    11, 139, 75, 203, 43, 171, 107, 235, 27, 155, 91, 219, 59, 187, 123, 251,
    7,  135, 71, 199, 39, 167, 103, 231, 23, 151, 87, 215, 55, 183, 119, 247,
    15, 143, 79, 207, 47, 175, 111, 239, 31, 159, 95, 223, 63, 191, 127, 255};

/* Unpack to "1" image */

static void
unpack1(UINT8 *out, const UINT8 *in, int pixels) {
    /* bits (msb first, white is non-zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = (byte & 128) ? 255 : 0;
                byte <<= 1;
            case 7:
                *out++ = (byte & 128) ? 255 : 0;
                byte <<= 1;
            case 6:
                *out++ = (byte & 128) ? 255 : 0;
                byte <<= 1;
            case 5:
                *out++ = (byte & 128) ? 255 : 0;
                byte <<= 1;
            case 4:
                *out++ = (byte & 128) ? 255 : 0;
                byte <<= 1;
            case 3:
                *out++ = (byte & 128) ? 255 : 0;
                byte <<= 1;
            case 2:
                *out++ = (byte & 128) ? 255 : 0;
                byte <<= 1;
            case 1:
                *out++ = (byte & 128) ? 255 : 0;
        }
        pixels -= 8;
    }
}

static void
unpack1I(UINT8 *out, const UINT8 *in, int pixels) {
    /* bits (msb first, white is zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = (byte & 128) ? 0 : 255;
                byte <<= 1;
            case 7:
                *out++ = (byte & 128) ? 0 : 255;
                byte <<= 1;
            case 6:
                *out++ = (byte & 128) ? 0 : 255;
                byte <<= 1;
            case 5:
                *out++ = (byte & 128) ? 0 : 255;
                byte <<= 1;
            case 4:
                *out++ = (byte & 128) ? 0 : 255;
                byte <<= 1;
            case 3:
                *out++ = (byte & 128) ? 0 : 255;
                byte <<= 1;
            case 2:
                *out++ = (byte & 128) ? 0 : 255;
                byte <<= 1;
            case 1:
                *out++ = (byte & 128) ? 0 : 255;
        }
        pixels -= 8;
    }
}

static void
unpack1R(UINT8 *out, const UINT8 *in, int pixels) {
    /* bits (lsb first, white is non-zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = (byte & 1) ? 255 : 0;
                byte >>= 1;
            case 7:
                *out++ = (byte & 1) ? 255 : 0;
                byte >>= 1;
            case 6:
                *out++ = (byte & 1) ? 255 : 0;
                byte >>= 1;
            case 5:
                *out++ = (byte & 1) ? 255 : 0;
                byte >>= 1;
            case 4:
                *out++ = (byte & 1) ? 255 : 0;
                byte >>= 1;
            case 3:
                *out++ = (byte & 1) ? 255 : 0;
                byte >>= 1;
            case 2:
                *out++ = (byte & 1) ? 255 : 0;
                byte >>= 1;
            case 1:
                *out++ = (byte & 1) ? 255 : 0;
        }
        pixels -= 8;
    }
}

static void
unpack1IR(UINT8 *out, const UINT8 *in, int pixels) {
    /* bits (lsb first, white is zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = (byte & 1) ? 0 : 255;
                byte >>= 1;
            case 7:
                *out++ = (byte & 1) ? 0 : 255;
                byte >>= 1;
            case 6:
                *out++ = (byte & 1) ? 0 : 255;
                byte >>= 1;
            case 5:
                *out++ = (byte & 1) ? 0 : 255;
                byte >>= 1;
            case 4:
                *out++ = (byte & 1) ? 0 : 255;
                byte >>= 1;
            case 3:
                *out++ = (byte & 1) ? 0 : 255;
                byte >>= 1;
            case 2:
                *out++ = (byte & 1) ? 0 : 255;
                byte >>= 1;
            case 1:
                *out++ = (byte & 1) ? 0 : 255;
        }
        pixels -= 8;
    }
}

static void
unpack18(UINT8 *out, const UINT8 *in, int pixels) {
    /* Unpack a '|b1' image, which is a numpy boolean.
       1 == true, 0==false, in bytes */

    int i;
    for (i = 0; i < pixels; i++) {
        out[i] = in[i] > 0 ? 255 : 0;
    }
}

/* Unpack to "L" image */

static void
unpackL2(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles (msb first, white is non-zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = ((byte >> 6) & 0x03U) * 0x55U;
                byte <<= 2;
            case 3:
                *out++ = ((byte >> 6) & 0x03U) * 0x55U;
                byte <<= 2;
            case 2:
                *out++ = ((byte >> 6) & 0x03U) * 0x55U;
                byte <<= 2;
            case 1:
                *out++ = ((byte >> 6) & 0x03U) * 0x55U;
        }
        pixels -= 4;
    }
}

static void
unpackL2I(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles (msb first, white is zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = 0xFFU - (UINT8)(((byte >> 6) & 0x03U) * 0x55U);
                byte <<= 2;
            case 3:
                *out++ = 0xFFU - (UINT8)(((byte >> 6) & 0x03U) * 0x55U);
                byte <<= 2;
            case 2:
                *out++ = 0xFFU - (UINT8)(((byte >> 6) & 0x03U) * 0x55U);
                byte <<= 2;
            case 1:
                *out++ = 0xFFU - (UINT8)(((byte >> 6) & 0x03U) * 0x55U);
        }
        pixels -= 4;
    }
}

static void
unpackL2R(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles (bit order reversed, white is non-zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        byte = BITFLIP[byte];
        switch (pixels) {
            default:
                *out++ = ((byte >> 6) & 0x03U) * 0x55U;
                byte <<= 2;
            case 3:
                *out++ = ((byte >> 6) & 0x03U) * 0x55U;
                byte <<= 2;
            case 2:
                *out++ = ((byte >> 6) & 0x03U) * 0x55U;
                byte <<= 2;
            case 1:
                *out++ = ((byte >> 6) & 0x03U) * 0x55U;
        }
        pixels -= 4;
    }
}

static void
unpackL2IR(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles (bit order reversed, white is zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        byte = BITFLIP[byte];
        switch (pixels) {
            default:
                *out++ = 0xFFU - (UINT8)(((byte >> 6) & 0x03U) * 0x55U);
                byte <<= 2;
            case 3:
                *out++ = 0xFFU - (UINT8)(((byte >> 6) & 0x03U) * 0x55U);
                byte <<= 2;
            case 2:
                *out++ = 0xFFU - (UINT8)(((byte >> 6) & 0x03U) * 0x55U);
                byte <<= 2;
            case 1:
                *out++ = 0xFFU - (UINT8)(((byte >> 6) & 0x03U) * 0x55U);
        }
        pixels -= 4;
    }
}

static void
unpackL4(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles (msb first, white is non-zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = ((byte >> 4) & 0x0FU) * 0x11U;
                byte <<= 4;
            case 1:
                *out++ = ((byte >> 4) & 0x0FU) * 0x11U;
        }
        pixels -= 2;
    }
}

static void
unpackL4I(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles (msb first, white is zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = 0xFFU - (UINT8)(((byte >> 4) & 0x0FU) * 0x11U);
                byte <<= 4;
            case 1:
                *out++ = 0xFFU - (UINT8)(((byte >> 4) & 0x0FU) * 0x11U);
        }
        pixels -= 2;
    }
}

static void
unpackL4R(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles (bit order reversed, white is non-zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        byte = BITFLIP[byte];
        switch (pixels) {
            default:
                *out++ = ((byte >> 4) & 0x0FU) * 0x11U;
                byte <<= 4;
            case 1:
                *out++ = ((byte >> 4) & 0x0FU) * 0x11U;
        }
        pixels -= 2;
    }
}

static void
unpackL4IR(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles (bit order reversed, white is zero) */
    while (pixels > 0) {
        UINT8 byte = *in++;
        byte = BITFLIP[byte];
        switch (pixels) {
            default:
                *out++ = 0xFFU - (UINT8)(((byte >> 4) & 0x0FU) * 0x11U);
                byte <<= 4;
            case 1:
                *out++ = 0xFFU - (UINT8)(((byte >> 4) & 0x0FU) * 0x11U);
        }
        pixels -= 2;
    }
}

static void
unpackLA(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* LA, pixel interleaved */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[0], in[0], in[0], in[1]);
        memcpy(_out, &iv, sizeof(iv));
        in += 2;
        _out += 4;
    }
}

static void
unpackLAL(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* LA, line interleaved */
    for (i = 0; i < pixels; i++, _out += 4) {
        UINT32 iv = MAKE_UINT32(in[i], in[i], in[i], in[i + pixels]);
        memcpy(_out, &iv, sizeof(iv));
    }
}

static void
unpackLI(UINT8 *out, const UINT8 *in, int pixels) {
    /* negative */
    int i;
    for (i = 0; i < pixels; i++) {
        out[i] = ~in[i];
    }
}

static void
unpackLR(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* RGB, bit reversed */
    for (i = 0; i < pixels; i++) {
        out[i] = BITFLIP[in[i]];
    }
}

static void
unpackL16(UINT8 *out, const UINT8 *in, int pixels) {
    /* int16 (upper byte, little endian) */
    int i;
    for (i = 0; i < pixels; i++) {
        out[i] = in[1];
        in += 2;
    }
}

static void
unpackL16B(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* int16 (upper byte, big endian) */
    for (i = 0; i < pixels; i++) {
        out[i] = in[0];
        in += 2;
    }
}

/* Unpack to "P" image */

static void
unpackP1(UINT8 *out, const UINT8 *in, int pixels) {
    /* bits */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = (byte >> 7) & 1;
                byte <<= 1;
            case 7:
                *out++ = (byte >> 7) & 1;
                byte <<= 1;
            case 6:
                *out++ = (byte >> 7) & 1;
                byte <<= 1;
            case 5:
                *out++ = (byte >> 7) & 1;
                byte <<= 1;
            case 4:
                *out++ = (byte >> 7) & 1;
                byte <<= 1;
            case 3:
                *out++ = (byte >> 7) & 1;
                byte <<= 1;
            case 2:
                *out++ = (byte >> 7) & 1;
                byte <<= 1;
            case 1:
                *out++ = (byte >> 7) & 1;
        }
        pixels -= 8;
    }
}

static void
unpackP2(UINT8 *out, const UINT8 *in, int pixels) {
    /* bit pairs */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = (byte >> 6) & 3;
                byte <<= 2;
            case 3:
                *out++ = (byte >> 6) & 3;
                byte <<= 2;
            case 2:
                *out++ = (byte >> 6) & 3;
                byte <<= 2;
            case 1:
                *out++ = (byte >> 6) & 3;
        }
        pixels -= 4;
    }
}

static void
unpackP4(UINT8 *out, const UINT8 *in, int pixels) {
    /* nibbles */
    while (pixels > 0) {
        UINT8 byte = *in++;
        switch (pixels) {
            default:
                *out++ = (byte >> 4) & 15;
                byte <<= 4;
            case 1:
                *out++ = (byte >> 4) & 15;
        }
        pixels -= 2;
    }
}

static void
unpackP2L(UINT8 *out, const UINT8 *in, int pixels) {
    int i, j, m, s;
    /* bit layers */
    m = 128;
    s = (pixels + 7) / 8;
    for (i = j = 0; i < pixels; i++) {
        out[i] = ((in[j] & m) ? 1 : 0) + ((in[j + s] & m) ? 2 : 0);
        if ((m >>= 1) == 0) {
            m = 128;
            j++;
        }
    }
}

static void
unpackP4L(UINT8 *out, const UINT8 *in, int pixels) {
    int i, j, m, s;
    /* bit layers (trust the optimizer ;-) */
    m = 128;
    s = (pixels + 7) / 8;
    for (i = j = 0; i < pixels; i++) {
        out[i] = ((in[j] & m) ? 1 : 0) + ((in[j + s] & m) ? 2 : 0) +
                 ((in[j + 2 * s] & m) ? 4 : 0) + ((in[j + 3 * s] & m) ? 8 : 0);
        if ((m >>= 1) == 0) {
            m = 128;
            j++;
        }
    }
}

/* Unpack to "RGB" image */

void
ImagingUnpackRGB(UINT8 *_out, const UINT8 *in, int pixels) {
    int i = 0;
    /* RGB triplets */
    for (; i < pixels - 1; i++) {
        UINT32 iv;
        memcpy(&iv, in, sizeof(iv));
        iv |= MASK_UINT32_CHANNEL_3;
        memcpy(_out, &iv, sizeof(iv));
        in += 3;
        _out += 4;
    }
    for (; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[0], in[1], in[2], 255);
        memcpy(_out, &iv, sizeof(iv));
        in += 3;
        _out += 4;
    }
}

void
unpackRGB16L(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* 16-bit RGB triplets, little-endian order */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[1], in[3], in[5], 255);
        memcpy(_out, &iv, sizeof(iv));
        in += 6;
        _out += 4;
    }
}

void
unpackRGB16B(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* 16-bit RGB triplets, big-endian order */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[0], in[2], in[4], 255);
        memcpy(_out, &iv, sizeof(iv));
        in += 6;
        _out += 4;
    }
}

static void
unpackRGBL(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGB, line interleaved */
    for (i = 0; i < pixels; i++, _out += 4) {
        UINT32 iv = MAKE_UINT32(in[i], in[i + pixels], in[i + pixels + pixels], 255);
        memcpy(_out, &iv, sizeof(iv));
    }
}

static void
unpackRGBR(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGB, bit reversed */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(BITFLIP[in[0]], BITFLIP[in[1]], BITFLIP[in[2]], 255);
        memcpy(_out, &iv, sizeof(iv));
        in += 3;
        _out += 4;
    }
}

void
ImagingUnpackBGR(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGB, reversed bytes */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[2], in[1], in[0], 255);
        memcpy(_out, &iv, sizeof(iv));
        in += 3;
        _out += 4;
    }
}

void
ImagingUnpackRGB15(UINT8 *out, const UINT8 *in, int pixels) {
    int i, pixel;
    /* RGB, 5 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel >> 5) & 31) * 255 / 31;
        out[B] = ((pixel >> 10) & 31) * 255 / 31;
        out[A] = 255;
        out += 4;
        in += 2;
    }
}

void
ImagingUnpackRGBA15(UINT8 *out, const UINT8 *in, int pixels) {
    int i, pixel;
    /* RGB, 5/5/5/1 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel >> 5) & 31) * 255 / 31;
        out[B] = ((pixel >> 10) & 31) * 255 / 31;
        out[A] = (pixel >> 15) * 255;
        out += 4;
        in += 2;
    }
}

void
ImagingUnpackBGR15(UINT8 *out, const UINT8 *in, int pixels) {
    int i, pixel;
    /* RGB, reversed bytes, 5 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[B] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel >> 5) & 31) * 255 / 31;
        out[R] = ((pixel >> 10) & 31) * 255 / 31;
        out[A] = 255;
        out += 4;
        in += 2;
    }
}

void
ImagingUnpackBGRA15(UINT8 *out, const UINT8 *in, int pixels) {
    int i, pixel;
    /* RGB, reversed bytes, 5/5/5/1 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[B] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel >> 5) & 31) * 255 / 31;
        out[R] = ((pixel >> 10) & 31) * 255 / 31;
        out[A] = (pixel >> 15) * 255;
        out += 4;
        in += 2;
    }
}

void
ImagingUnpackRGB16(UINT8 *out, const UINT8 *in, int pixels) {
    int i, pixel;
    /* RGB, 5/6/5 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel >> 5) & 63) * 255 / 63;
        out[B] = ((pixel >> 11) & 31) * 255 / 31;
        out[A] = 255;
        out += 4;
        in += 2;
    }
}

void
ImagingUnpackBGR16(UINT8 *out, const UINT8 *in, int pixels) {
    int i, pixel;
    /* RGB, reversed bytes, 5/6/5 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[B] = (pixel & 31) * 255 / 31;
        out[G] = ((pixel >> 5) & 63) * 255 / 63;
        out[R] = ((pixel >> 11) & 31) * 255 / 31;
        out[A] = 255;
        out += 4;
        in += 2;
    }
}

void
ImagingUnpackRGB4B(UINT8 *out, const UINT8 *in, int pixels) {
    int i, pixel;
    /* RGB, 4 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 15) * 17;
        out[G] = ((pixel >> 4) & 15) * 17;
        out[B] = ((pixel >> 8) & 15) * 17;
        out[A] = 255;
        out += 4;
        in += 2;
    }
}

void
ImagingUnpackRGBA4B(UINT8 *out, const UINT8 *in, int pixels) {
    int i, pixel;
    /* RGBA, 4 bits per pixel */
    for (i = 0; i < pixels; i++) {
        pixel = in[0] + (in[1] << 8);
        out[R] = (pixel & 15) * 17;
        out[G] = ((pixel >> 4) & 15) * 17;
        out[B] = ((pixel >> 8) & 15) * 17;
        out[A] = ((pixel >> 12) & 15) * 17;
        out += 4;
        in += 2;
    }
}

static void
ImagingUnpackBGRX(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGB, reversed bytes with padding */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[2], in[1], in[0], 255);
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

static void
ImagingUnpackXRGB(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGB, leading pad */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[1], in[2], in[3], 255);
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

static void
ImagingUnpackXBGR(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGB, reversed bytes, leading pad */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[3], in[2], in[1], 255);
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

/* Unpack to "RGBA" image */

static void
unpackRGBALA(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* greyscale with alpha */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[0], in[0], in[0], in[1]);
        memcpy(_out, &iv, sizeof(iv));
        in += 2;
        _out += 4;
    }
}

static void
unpackRGBALA16B(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* 16-bit greyscale with alpha, big-endian */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[0], in[0], in[0], in[2]);
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

static void
unpackRGBa16L(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* premultiplied 16-bit RGBA, little-endian */
    for (i = 0; i < pixels; i++) {
        int a = in[7];
        UINT32 iv;
        if (!a) {
            iv = 0;
        } else if (a == 255) {
            iv = MAKE_UINT32(in[1], in[3], in[5], a);
        } else {
            iv = MAKE_UINT32(
                CLIP8(in[1] * 255 / a),
                CLIP8(in[3] * 255 / a),
                CLIP8(in[5] * 255 / a),
                a);
        }
        memcpy(_out, &iv, sizeof(iv));
        in += 8;
        _out += 4;
    }
}

static void
unpackRGBa16B(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* premultiplied 16-bit RGBA, big-endian */
    for (i = 0; i < pixels; i++) {
        int a = in[6];
        UINT32 iv;
        if (!a) {
            iv = 0;
        } else if (a == 255) {
            iv = MAKE_UINT32(in[0], in[2], in[4], a);
        } else {
            iv = MAKE_UINT32(
                CLIP8(in[0] * 255 / a),
                CLIP8(in[2] * 255 / a),
                CLIP8(in[4] * 255 / a),
                a);
        }
        memcpy(_out, &iv, sizeof(iv));
        in += 8;
        _out += 4;
    }
}

static void
unpackRGBa(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* premultiplied RGBA */
    for (i = 0; i < pixels; i++) {
        int a = in[3];
        UINT32 iv;
        if (!a) {
            iv = 0;
        } else if (a == 255) {
            iv = MAKE_UINT32(in[0], in[1], in[2], a);
        } else {
            iv = MAKE_UINT32(
                CLIP8(in[0] * 255 / a),
                CLIP8(in[1] * 255 / a),
                CLIP8(in[2] * 255 / a),
                a);
        }
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

static void
unpackRGBaskip1(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    UINT32 *out = (UINT32 *)_out;
    /* premultiplied RGBA */
    for (i = 0; i < pixels; i++) {
        int a = in[3];
        if (!a) {
            out[i] = 0;
        } else if (a == 255) {
            out[i] = MAKE_UINT32(in[0], in[1], in[2], a);
        } else {
            out[i] = MAKE_UINT32(
                CLIP8(in[0] * 255 / a),
                CLIP8(in[1] * 255 / a),
                CLIP8(in[2] * 255 / a),
                a);
        }
        in += 5;
    }
}

static void
unpackRGBaskip2(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    UINT32 *out = (UINT32 *)_out;
    /* premultiplied RGBA */
    for (i = 0; i < pixels; i++) {
        int a = in[3];
        if (!a) {
            out[i] = 0;
        } else if (a == 255) {
            out[i] = MAKE_UINT32(in[0], in[1], in[2], a);
        } else {
            out[i] = MAKE_UINT32(
                CLIP8(in[0] * 255 / a),
                CLIP8(in[1] * 255 / a),
                CLIP8(in[2] * 255 / a),
                a);
        }
        in += 6;
    }
}

static void
unpackBGRa(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* premultiplied BGRA */
    for (i = 0; i < pixels; i++) {
        int a = in[3];
        UINT32 iv;
        if (!a) {
            iv = 0;
        } else if (a == 255) {
            iv = MAKE_UINT32(in[2], in[1], in[0], a);
        } else {
            iv = MAKE_UINT32(
                CLIP8(in[2] * 255 / a),
                CLIP8(in[1] * 255 / a),
                CLIP8(in[0] * 255 / a),
                a);
        }
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

static void
unpackRGBAI(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* RGBA, inverted RGB bytes (FlashPix) */
    for (i = 0; i < pixels; i++) {
        out[R] = ~in[0];
        out[G] = ~in[1];
        out[B] = ~in[2];
        out[A] = in[3];
        out += 4;
        in += 4;
    }
}

static void
unpackRGBAL(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGBA, line interleaved */
    for (i = 0; i < pixels; i++, _out += 4) {
        UINT32 iv = MAKE_UINT32(
            in[i],
            in[i + pixels],
            in[i + pixels + pixels],
            in[i + pixels + pixels + pixels]);
        memcpy(_out, &iv, sizeof(iv));
    }
}

void
unpackRGBA16L(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* 16-bit RGBA, little-endian order */
    for (i = 0; i < pixels; i++, _out += 4) {
        UINT32 iv = MAKE_UINT32(in[1], in[3], in[5], in[7]);
        memcpy(_out, &iv, sizeof(iv));
        in += 8;
    }
}

void
unpackRGBA16B(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* 16-bit RGBA, big-endian order */
    for (i = 0; i < pixels; i++, _out += 4) {
        UINT32 iv = MAKE_UINT32(in[0], in[2], in[4], in[6]);
        memcpy(_out, &iv, sizeof(iv));
        in += 8;
    }
}

static void
unpackARGB(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGBA, leading pad */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[1], in[2], in[3], in[0]);
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

static void
unpackABGR(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGBA, reversed bytes */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[3], in[2], in[1], in[0]);
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

static void
unpackBGRA(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* RGBA, reversed bytes */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = MAKE_UINT32(in[2], in[1], in[0], in[3]);
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

/* Unpack to "CMYK" image */

static void
unpackCMYKI(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    /* CMYK, inverted bytes (Photoshop 2.5) */
    for (i = 0; i < pixels; i++) {
        UINT32 iv = ~MAKE_UINT32(in[0], in[1], in[2], in[3]);
        memcpy(_out, &iv, sizeof(iv));
        in += 4;
        _out += 4;
    }
}

/* Unpack to "LAB" image */
/* There are two representations of LAB images for whatever precision:
   L: Uint (in PS, it's 0-100)
   A: Int (in ps, -128 .. 128, or elsewhere 0..255, with 128 as middle.
           Channels in PS display a 0 value as middle grey,
           LCMS appears to use 128 as the 0 value for these channels)
   B: Int (as above)

   Since we don't have any signed ints, we're going with the shifted versions
   internally, and we'll unshift for saving and whatnot.
*/
void
ImagingUnpackLAB(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* LAB triplets */
    for (i = 0; i < pixels; i++) {
        out[0] = in[0];
        out[1] = in[1] ^ 128; /* signed in outside world */
        out[2] = in[2] ^ 128;
        out[3] = 255;
        out += 4;
        in += 3;
    }
}

static void
unpackI16N_I16B(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    UINT8 *tmp = (UINT8 *)out;
    for (i = 0; i < pixels; i++) {
        C16B;
        in += 2;
        tmp += 2;
    }
}
static void
unpackI16N_I16(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    UINT8 *tmp = (UINT8 *)out;
    for (i = 0; i < pixels; i++) {
        C16L;
        in += 2;
        tmp += 2;
    }
}

static void
unpackI12_I16(UINT8 *out, const UINT8 *in, int pixels) {
    /*  Fillorder 1/MSB -> LittleEndian, for 12bit integer greyscale tiffs.

        According to the TIFF spec:

        FillOrder = 2 should be used only when BitsPerSample = 1 and
        the data is either uncompressed or compressed using CCITT 1D
        or 2D compression, to avoid potentially ambiguous situations.

        Yeah. I thought so. We'll see how well people read the spec.
        We've got several fillorder=2 modes in TiffImagePlugin.py

        There's no spec I can find. It appears that the in storage
        layout is: 00 80 00 ... -> (128 , 0 ...). The samples are
        stored in a single big bitian 12bit block, but need to be
        pulled out to little endian format to be stored in a 2 byte
        int.
     */

    int i;
    UINT16 pixel;
#ifdef WORDS_BIGENDIAN
    UINT8 *tmp = (UINT8 *)&pixel;
#endif
    for (i = 0; i < pixels - 1; i += 2) {
        pixel = (((UINT16)in[0]) << 4) + (in[1] >> 4);
#ifdef WORDS_BIGENDIAN
        out[0] = tmp[1];
        out[1] = tmp[0];
#else
        memcpy(out, &pixel, sizeof(pixel));
#endif

        out += 2;
        pixel = (((UINT16)(in[1] & 0x0F)) << 8) + in[2];
#ifdef WORDS_BIGENDIAN
        out[0] = tmp[1];
        out[1] = tmp[0];
#else
        memcpy(out, &pixel, sizeof(pixel));
#endif

        in += 3;
        out += 2;
    }
    if (i == pixels - 1) {
        pixel = (((UINT16)in[0]) << 4) + (in[1] >> 4);
#ifdef WORDS_BIGENDIAN
        out[0] = tmp[1];
        out[1] = tmp[0];
#else
        memcpy(out, &pixel, sizeof(pixel));
#endif
    }
}

static void
copy1(UINT8 *out, const UINT8 *in, int pixels) {
    /* L, P */
    memcpy(out, in, pixels);
}

static void
copy2(UINT8 *out, const UINT8 *in, int pixels) {
    /* I;16 */
    memcpy(out, in, pixels * 2);
}

static void
copy4(UINT8 *out, const UINT8 *in, int pixels) {
    /* RGBA, CMYK quadruples */
    memcpy(out, in, 4 * pixels);
}

static void
copy4skip1(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    for (i = 0; i < pixels; i++) {
        memcpy(_out, in, 4);
        in += 5;
        _out += 4;
    }
}

static void
copy4skip2(UINT8 *_out, const UINT8 *in, int pixels) {
    int i;
    for (i = 0; i < pixels; i++) {
        memcpy(_out, in, 4);
        in += 6;
        _out += 4;
    }
}

/* Unpack to "I" and "F" images */

#define UNPACK_RAW(NAME, GET, INTYPE, OUTTYPE)                   \
    static void NAME(UINT8 *out_, const UINT8 *in, int pixels) { \
        int i;                                                   \
        OUTTYPE *out = (OUTTYPE *)out_;                          \
        for (i = 0; i < pixels; i++, in += sizeof(INTYPE)) {     \
            out[i] = (OUTTYPE)((INTYPE)GET);                     \
        }                                                        \
    }

#define UNPACK(NAME, COPY, INTYPE, OUTTYPE)                      \
    static void NAME(UINT8 *out_, const UINT8 *in, int pixels) { \
        int i;                                                   \
        OUTTYPE *out = (OUTTYPE *)out_;                          \
        INTYPE tmp_;                                             \
        UINT8 *tmp = (UINT8 *)&tmp_;                             \
        for (i = 0; i < pixels; i++, in += sizeof(INTYPE)) {     \
            COPY;                                                \
            out[i] = (OUTTYPE)tmp_;                              \
        }                                                        \
    }

UNPACK_RAW(unpackI8, in[0], UINT8, INT32)
UNPACK_RAW(unpackI8S, in[0], INT8, INT32)
UNPACK(unpackI16, C16L, UINT16, INT32)
UNPACK(unpackI16S, C16L, INT16, INT32)
UNPACK(unpackI16B, C16B, UINT16, INT32)
UNPACK(unpackI16BS, C16B, INT16, INT32)
UNPACK(unpackI16N, C16N, UINT16, INT32)
UNPACK(unpackI16NS, C16N, INT16, INT32)
UNPACK(unpackI32, C32L, UINT32, INT32)
UNPACK(unpackI32S, C32L, INT32, INT32)
UNPACK(unpackI32B, C32B, UINT32, INT32)
UNPACK(unpackI32BS, C32B, INT32, INT32)
UNPACK(unpackI32N, C32N, UINT32, INT32)
UNPACK(unpackI32NS, C32N, INT32, INT32)

UNPACK_RAW(unpackF8, in[0], UINT8, FLOAT32)
UNPACK_RAW(unpackF8S, in[0], INT8, FLOAT32)
UNPACK(unpackF16, C16L, UINT16, FLOAT32)
UNPACK(unpackF16S, C16L, INT16, FLOAT32)
UNPACK(unpackF16B, C16B, UINT16, FLOAT32)
UNPACK(unpackF16BS, C16B, INT16, FLOAT32)
UNPACK(unpackF16N, C16N, UINT16, FLOAT32)
UNPACK(unpackF16NS, C16N, INT16, FLOAT32)
UNPACK(unpackF32, C32L, UINT32, FLOAT32)
UNPACK(unpackF32S, C32L, INT32, FLOAT32)
UNPACK(unpackF32B, C32B, UINT32, FLOAT32)
UNPACK(unpackF32BS, C32B, INT32, FLOAT32)
UNPACK(unpackF32N, C32N, UINT32, FLOAT32)
UNPACK(unpackF32NS, C32N, INT32, FLOAT32)
UNPACK(unpackF32F, C32L, FLOAT32, FLOAT32)
UNPACK(unpackF32BF, C32B, FLOAT32, FLOAT32)
UNPACK(unpackF32NF, C32N, FLOAT32, FLOAT32)
#ifdef FLOAT64
UNPACK(unpackF64F, C64L, FLOAT64, FLOAT32)
UNPACK(unpackF64BF, C64B, FLOAT64, FLOAT32)
UNPACK(unpackF64NF, C64N, FLOAT64, FLOAT32)
#endif

/* Misc. unpackers */

static void
band0(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* band 0 only */
    for (i = 0; i < pixels; i++) {
        out[0] = in[i];
        out += 4;
    }
}

static void
band1(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* band 1 only */
    for (i = 0; i < pixels; i++) {
        out[1] = in[i];
        out += 4;
    }
}

static void
band2(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* band 2 only */
    for (i = 0; i < pixels; i++) {
        out[2] = in[i];
        out += 4;
    }
}

static void
band3(UINT8 *out, const UINT8 *in, int pixels) {
    /* band 3 only */
    int i;
    for (i = 0; i < pixels; i++) {
        out[3] = in[i];
        out += 4;
    }
}

static void
band0I(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* band 0 only */
    for (i = 0; i < pixels; i++) {
        out[0] = ~in[i];
        out += 4;
    }
}

static void
band1I(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* band 1 only */
    for (i = 0; i < pixels; i++) {
        out[1] = ~in[i];
        out += 4;
    }
}

static void
band2I(UINT8 *out, const UINT8 *in, int pixels) {
    int i;
    /* band 2 only */
    for (i = 0; i < pixels; i++) {
        out[2] = ~in[i];
        out += 4;
    }
}

static void
band3I(UINT8 *out, const UINT8 *in, int pixels) {
    /* band 3 only */
    int i;
    for (i = 0; i < pixels; i++) {
        out[3] = ~in[i];
        out += 4;
    }
}

static struct {
    const char *mode;
    const char *rawmode;
    int bits;
    ImagingShuffler unpack;
} unpackers[] = {

    /* raw mode syntax is "<mode>;<bits><flags>" where "bits" defaults
       depending on mode (1 for "1", 8 for "P" and "L", etc), and
       "flags" should be given in alphabetical order.  if both bits
       and flags have their default values, the ; should be left out */

    /* flags: "I" inverted data; "R" reversed bit order; "B" big
       endian byte order (default is little endian); "L" line
       interleave, "S" signed, "F" floating point */

    /* exception: rawmodes "I" and "F" are always native endian byte order */

    /* bilevel */
    {"1", "1", 1, unpack1},
    {"1", "1;I", 1, unpack1I},
    {"1", "1;R", 1, unpack1R},
    {"1", "1;IR", 1, unpack1IR},
    {"1", "1;8", 8, unpack18},

    /* greyscale */
    {"L", "L;2", 2, unpackL2},
    {"L", "L;2I", 2, unpackL2I},
    {"L", "L;2R", 2, unpackL2R},
    {"L", "L;2IR", 2, unpackL2IR},

    {"L", "L;4", 4, unpackL4},
    {"L", "L;4I", 4, unpackL4I},
    {"L", "L;4R", 4, unpackL4R},
    {"L", "L;4IR", 4, unpackL4IR},

    {"L", "L", 8, copy1},
    {"L", "L;I", 8, unpackLI},
    {"L", "L;R", 8, unpackLR},
    {"L", "L;16", 16, unpackL16},
    {"L", "L;16B", 16, unpackL16B},

    /* greyscale w. alpha */
    {"LA", "LA", 16, unpackLA},
    {"LA", "LA;L", 16, unpackLAL},

    /* greyscale w. alpha premultiplied */
    {"La", "La", 16, unpackLA},

    /* palette */
    {"P", "P;1", 1, unpackP1},
    {"P", "P;2", 2, unpackP2},
    {"P", "P;2L", 2, unpackP2L},
    {"P", "P;4", 4, unpackP4},
    {"P", "P;4L", 4, unpackP4L},
    {"P", "P", 8, copy1},
    {"P", "P;R", 8, unpackLR},

    /* palette w. alpha */
    {"PA", "PA", 16, unpackLA},
    {"PA", "PA;L", 16, unpackLAL},

    /* true colour */
    {"RGB", "RGB", 24, ImagingUnpackRGB},
    {"RGB", "RGB;L", 24, unpackRGBL},
    {"RGB", "RGB;R", 24, unpackRGBR},
    {"RGB", "RGB;16L", 48, unpackRGB16L},
    {"RGB", "RGB;16B", 48, unpackRGB16B},
    {"RGB", "BGR", 24, ImagingUnpackBGR},
    {"RGB", "RGB;15", 16, ImagingUnpackRGB15},
    {"RGB", "BGR;15", 16, ImagingUnpackBGR15},
    {"RGB", "RGB;16", 16, ImagingUnpackRGB16},
    {"RGB", "BGR;16", 16, ImagingUnpackBGR16},
    {"RGB", "RGB;4B", 16, ImagingUnpackRGB4B},
    {"RGB", "BGR;5", 16, ImagingUnpackBGR15}, /* compat */
    {"RGB", "RGBX", 32, copy4},
    {"RGB", "RGBX;L", 32, unpackRGBAL},
    {"RGB", "RGBA;L", 32, unpackRGBAL},
    {"RGB", "BGRX", 32, ImagingUnpackBGRX},
    {"RGB", "XRGB", 32, ImagingUnpackXRGB},
    {"RGB", "XBGR", 32, ImagingUnpackXBGR},
    {"RGB", "YCC;P", 24, ImagingUnpackYCC},
    {"RGB", "R", 8, band0},
    {"RGB", "G", 8, band1},
    {"RGB", "B", 8, band2},

    /* true colour w. alpha */
    {"RGBA", "LA", 16, unpackRGBALA},
    {"RGBA", "LA;16B", 32, unpackRGBALA16B},
    {"RGBA", "RGBA", 32, copy4},
    {"RGBA", "RGBAX", 40, copy4skip1},
    {"RGBA", "RGBAXX", 48, copy4skip2},
    {"RGBA", "RGBa", 32, unpackRGBa},
    {"RGBA", "RGBaX", 40, unpackRGBaskip1},
    {"RGBA", "RGBaXX", 48, unpackRGBaskip2},
    {"RGBA", "RGBa;16L", 64, unpackRGBa16L},
    {"RGBA", "RGBa;16B", 64, unpackRGBa16B},
    {"RGBA", "BGRa", 32, unpackBGRa},
    {"RGBA", "RGBA;I", 32, unpackRGBAI},
    {"RGBA", "RGBA;L", 32, unpackRGBAL},
    {"RGBA", "RGBA;15", 16, ImagingUnpackRGBA15},
    {"RGBA", "BGRA;15", 16, ImagingUnpackBGRA15},
    {"RGBA", "RGBA;4B", 16, ImagingUnpackRGBA4B},
    {"RGBA", "RGBA;16L", 64, unpackRGBA16L},
    {"RGBA", "RGBA;16B", 64, unpackRGBA16B},
    {"RGBA", "BGRA", 32, unpackBGRA},
    {"RGBA", "ARGB", 32, unpackARGB},
    {"RGBA", "ABGR", 32, unpackABGR},
    {"RGBA", "YCCA;P", 32, ImagingUnpackYCCA},
    {"RGBA", "R", 8, band0},
    {"RGBA", "G", 8, band1},
    {"RGBA", "B", 8, band2},
    {"RGBA", "A", 8, band3},

#ifdef WORDS_BIGENDIAN
    {"RGB", "RGB;16N", 48, unpackRGB16B},
    {"RGBA", "RGBa;16N", 64, unpackRGBa16B},
    {"RGBA", "RGBA;16N", 64, unpackRGBA16B},
    {"RGBX", "RGBX;16N", 64, unpackRGBA16B},
#else
    {"RGB", "RGB;16N", 48, unpackRGB16L},
    {"RGBA", "RGBa;16N", 64, unpackRGBa16L},
    {"RGBA", "RGBA;16N", 64, unpackRGBA16L},
    {"RGBX", "RGBX;16N", 64, unpackRGBA16B},
#endif

    /* true colour w. alpha premultiplied */
    {"RGBa", "RGBa", 32, copy4},
    {"RGBa", "BGRa", 32, unpackBGRA},
    {"RGBa", "aRGB", 32, unpackARGB},
    {"RGBa", "aBGR", 32, unpackABGR},

    /* true colour w. padding */
    {"RGBX", "RGB", 24, ImagingUnpackRGB},
    {"RGBX", "RGB;L", 24, unpackRGBL},
    {"RGBX", "RGB;16B", 48, unpackRGB16B},
    {"RGBX", "BGR", 24, ImagingUnpackBGR},
    {"RGBX", "RGB;15", 16, ImagingUnpackRGB15},
    {"RGBX", "BGR;15", 16, ImagingUnpackBGR15},
    {"RGBX", "RGB;4B", 16, ImagingUnpackRGB4B},
    {"RGBX", "BGR;5", 16, ImagingUnpackBGR15}, /* compat */
    {"RGBX", "RGBX", 32, copy4},
    {"RGBX", "RGBXX", 40, copy4skip1},
    {"RGBX", "RGBXXX", 48, copy4skip2},
    {"RGBX", "RGBX;L", 32, unpackRGBAL},
    {"RGBX", "RGBX;16L", 64, unpackRGBA16L},
    {"RGBX", "RGBX;16B", 64, unpackRGBA16B},
    {"RGBX", "BGRX", 32, ImagingUnpackBGRX},
    {"RGBX", "XRGB", 32, ImagingUnpackXRGB},
    {"RGBX", "XBGR", 32, ImagingUnpackXBGR},
    {"RGBX", "YCC;P", 24, ImagingUnpackYCC},
    {"RGBX", "R", 8, band0},
    {"RGBX", "G", 8, band1},
    {"RGBX", "B", 8, band2},
    {"RGBX", "X", 8, band3},

    /* colour separation */
    {"CMYK", "CMYK", 32, copy4},
    {"CMYK", "CMYKX", 40, copy4skip1},
    {"CMYK", "CMYKXX", 48, copy4skip2},
    {"CMYK", "CMYK;I", 32, unpackCMYKI},
    {"CMYK", "CMYK;L", 32, unpackRGBAL},
    {"CMYK", "CMYK;16L", 64, unpackRGBA16L},
    {"CMYK", "CMYK;16B", 64, unpackRGBA16B},
    {"CMYK", "C", 8, band0},
    {"CMYK", "M", 8, band1},
    {"CMYK", "Y", 8, band2},
    {"CMYK", "K", 8, band3},
    {"CMYK", "C;I", 8, band0I},
    {"CMYK", "M;I", 8, band1I},
    {"CMYK", "Y;I", 8, band2I},
    {"CMYK", "K;I", 8, band3I},

#ifdef WORDS_BIGENDIAN
    {"CMYK", "CMYK;16N", 64, unpackRGBA16B},
#else
    {"CMYK", "CMYK;16N", 64, unpackRGBA16L},
#endif

    /* video (YCbCr) */
    {"YCbCr", "YCbCr", 24, ImagingUnpackRGB},
    {"YCbCr", "YCbCr;L", 24, unpackRGBL},
    {"YCbCr", "YCbCrX", 32, copy4},
    {"YCbCr", "YCbCrK", 32, copy4},

    /* LAB Color */
    {"LAB", "LAB", 24, ImagingUnpackLAB},
    {"LAB", "L", 8, band0},
    {"LAB", "A", 8, band1},
    {"LAB", "B", 8, band2},

    /* HSV Color */
    {"HSV", "HSV", 24, ImagingUnpackRGB},
    {"HSV", "H", 8, band0},
    {"HSV", "S", 8, band1},
    {"HSV", "V", 8, band2},

    /* integer variations */
    {"I", "I", 32, copy4},
    {"I", "I;8", 8, unpackI8},
    {"I", "I;8S", 8, unpackI8S},
    {"I", "I;16", 16, unpackI16},
    {"I", "I;16S", 16, unpackI16S},
    {"I", "I;16B", 16, unpackI16B},
    {"I", "I;16BS", 16, unpackI16BS},
    {"I", "I;16N", 16, unpackI16N},
    {"I", "I;16NS", 16, unpackI16NS},
    {"I", "I;32", 32, unpackI32},
    {"I", "I;32S", 32, unpackI32S},
    {"I", "I;32B", 32, unpackI32B},
    {"I", "I;32BS", 32, unpackI32BS},
    {"I", "I;32N", 32, unpackI32N},
    {"I", "I;32NS", 32, unpackI32NS},

    /* floating point variations */
    {"F", "F", 32, copy4},
    {"F", "F;8", 8, unpackF8},
    {"F", "F;8S", 8, unpackF8S},
    {"F", "F;16", 16, unpackF16},
    {"F", "F;16S", 16, unpackF16S},
    {"F", "F;16B", 16, unpackF16B},
    {"F", "F;16BS", 16, unpackF16BS},
    {"F", "F;16N", 16, unpackF16N},
    {"F", "F;16NS", 16, unpackF16NS},
    {"F", "F;32", 32, unpackF32},
    {"F", "F;32S", 32, unpackF32S},
    {"F", "F;32B", 32, unpackF32B},
    {"F", "F;32BS", 32, unpackF32BS},
    {"F", "F;32N", 32, unpackF32N},
    {"F", "F;32NS", 32, unpackF32NS},
    {"F", "F;32F", 32, unpackF32F},
    {"F", "F;32BF", 32, unpackF32BF},
    {"F", "F;32NF", 32, unpackF32NF},
#ifdef FLOAT64
    {"F", "F;64F", 64, unpackF64F},
    {"F", "F;64BF", 64, unpackF64BF},
    {"F", "F;64NF", 64, unpackF64NF},
#endif

    /* storage modes */
    {"I;16", "I;16", 16, copy2},
    {"I;16B", "I;16B", 16, copy2},
    {"I;16L", "I;16L", 16, copy2},

    {"I;16", "I;16N", 16, unpackI16N_I16},   // LibTiff native->image endian.
    {"I;16L", "I;16N", 16, unpackI16N_I16},  // LibTiff native->image endian.
    {"I;16B", "I;16N", 16, unpackI16N_I16B},

    {"I;16", "I;12", 12, unpackI12_I16},  // 12 bit Tiffs stored in 16bits.

    {NULL} /* sentinel */
};

ImagingShuffler
ImagingFindUnpacker(const char *mode, const char *rawmode, int *bits_out) {
    int i;

    /* find a suitable pixel unpacker */
    for (i = 0; unpackers[i].rawmode; i++) {
        if (strcmp(unpackers[i].mode, mode) == 0 &&
            strcmp(unpackers[i].rawmode, rawmode) == 0) {
            if (bits_out) {
                *bits_out = unpackers[i].bits;
            }
            return unpackers[i].unpack;
        }
    }

    /* FIXME: configure a general unpacker based on the type codes... */

    return NULL;
}