Pillow/PIL/PsdImagePlugin.py

#
# The Python Imaging Library
# $Id$
#
# Adobe PSD 2.5/3.0 file handling
#
# History:
# 1995-09-01 fl   Created
# 1997-01-03 fl   Read most PSD images
# 1997-01-18 fl   Fixed P and CMYK support
# 2001-10-21 fl   Added seek/tell support (for layers)
#
# Copyright (c) 1997-2001 by Secret Labs AB.
# Copyright (c) 1995-2001 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#

__version__ = "0.4"

import Image, ImageFile, ImagePalette

MODES = {
    # (photoshop mode, bits) -> (pil mode, required channels)
    (0, 1): ("1", 1),
    (0, 8): ("L", 1),
    (1, 8): ("L", 1),
    (2, 8): ("P", 1),
    (3, 8): ("RGB", 3),
    (4, 8): ("CMYK", 4),
    (7, 8): ("L", 1), # FIXME: multilayer
    (8, 8): ("L", 1), # duotone
    (9, 8): ("LAB", 3)
}

#
# helpers

def i16(c):
    return ord(c[1]) + (ord(c[0])<<8)

def i32(c):
    return ord(c[3]) + (ord(c[2])<<8) + (ord(c[1])<<16) + (ord(c[0])<<24)

# --------------------------------------------------------------------.
# read PSD images

def _accept(prefix):
    return prefix[:4] == "8BPS"

##
# Image plugin for Photoshop images.

class PsdImageFile(ImageFile.ImageFile):

    format = "PSD"
    format_description = "Adobe Photoshop"

    def _open(self):
        
        read = self.fp.read

        #
        # header

        s = read(26)
        if s[:4] != "8BPS" or i16(s[4:]) != 1:
            raise SyntaxError, "not a PSD file"

        psd_bits = i16(s[22:])
        psd_channels = i16(s[12:])
        psd_mode = i16(s[24:])

        mode, channels = MODES[(psd_mode, psd_bits)]

        if channels > psd_channels:
            raise IOError, "not enough channels"

        self.mode = mode
        self.size = i32(s[18:]), i32(s[14:])

        #
        # color mode data

        size = i32(read(4))
        if size:
            data = read(size)
            if mode == "P" and size == 768:
                self.palette = ImagePalette.raw("RGB;L", data)

        #
        # image resources

        self.resources = []

        size = i32(read(4))
        if size:
            # load resources
            end = self.fp.tell() + size
            while self.fp.tell() < end:
                signature = read(4)
                id = i16(read(2))
                name = read(ord(read(1)))
                if not (len(name) & 1):
                    read(1) # padding
                data = read(i32(read(4)))
                if (len(data) & 1):
                    read(1) # padding
                self.resources.append((id, name, data))
                if id == 1039: # ICC profile
                    self.info["icc_profile"] = data

        #
        # layer and mask information

        self.layers = []

        size = i32(read(4))
        if size:
            end = self.fp.tell() + size
            size = i32(read(4))
            if size:
                self.layers = _layerinfo(self.fp)
            self.fp.seek(end)

        #
        # image descriptor

        self.tile = _maketile(self.fp, mode, (0, 0) + self.size, channels)

        # keep the file open
        self._fp = self.fp
        self.frame = 0

    def seek(self, layer):
        # seek to given layer (1..max)
        if layer == self.frame:
            return
        try:
            if layer <= 0:
                raise IndexError
            name, mode, bbox, tile = self.layers[layer-1]
            self.mode = mode
            self.tile = tile
            self.frame = layer
            self.fp = self._fp
            return name, bbox
        except IndexError:
            raise EOFError, "no such layer"

    def tell(self):
        # return layer number (0=image, 1..max=layers)
        return self.frame

    def load_prepare(self):
        # create image memory if necessary
        if not self.im or\
           self.im.mode != self.mode or self.im.size != self.size:
            self.im = Image.core.fill(self.mode, self.size, 0)
        # create palette (optional)
        if self.mode == "P":
            Image.Image.load(self)

def _layerinfo(file):
    # read layerinfo block
    layers = []
    read = file.read
    for i in range(abs(i16(read(2)))):

        # bounding box
        y0 = i32(read(4)); x0 = i32(read(4))
        y1 = i32(read(4)); x1 = i32(read(4))

        # image info
        info = []
        mode = []
        types = range(i16(read(2)))
        if len(types) > 4:
            continue

        for i in types:
            type = i16(read(2))

            if type == 65535:
                m = "A"
            else:
                m = "RGBA"[type]

            mode.append(m)
            size = i32(read(4))
            info.append((m, size))

        # figure out the image mode
        mode.sort()
        if mode == ["R"]:
            mode = "L"
        elif mode == ["B", "G", "R"]:
            mode = "RGB"
        elif mode == ["A", "B", "G", "R"]:
            mode = "RGBA"
        else:
            mode = None # unknown

        # skip over blend flags and extra information
        filler = read(12)
        name = ""
        size = i32(read(4))
        combined = 0
        if size:
            length = i32(read(4))
            if length:
                mask_y = i32(read(4)); mask_x = i32(read(4))
                mask_h = i32(read(4)) - mask_y; mask_w = i32(read(4)) - mask_x
                file.seek(length - 16, 1)
            combined += length + 4

            length = i32(read(4))
            if length:
                file.seek(length, 1)
            combined += length + 4

            length = ord(read(1))
            if length:
                name = read(length)
            combined += length + 1

        file.seek(size - combined, 1)
        layers.append((name, mode, (x0, y0, x1, y1)))

    # get tiles
    i = 0
    for name, mode, bbox in layers:
        tile = []
        for m in mode:
            t = _maketile(file, m, bbox, 1)
            if t:
                tile.extend(t)
        layers[i] = name, mode, bbox, tile
        i = i + 1

    return layers

def _maketile(file, mode, bbox, channels):

    tile = None
    read = file.read

    compression = i16(read(2))

    xsize = bbox[2] - bbox[0]
    ysize = bbox[3] - bbox[1]

    offset = file.tell()

    if compression == 0:
        #
        # raw compression
        tile = []
        for channel in range(channels):
            layer = mode[channel]
            if mode == "CMYK":
                layer = layer + ";I"
            tile.append(("raw", bbox, offset, layer))
            offset = offset + xsize*ysize

    elif compression == 1:
        #
        # packbits compression
        i = 0
        tile = []
        bytecount = read(channels * ysize * 2)
        offset = file.tell()
        for channel in range(channels):
            layer = mode[channel]
            if mode == "CMYK":
                layer = layer + ";I"
            tile.append(
                ("packbits", bbox, offset, layer)
                )
            for y in range(ysize):
                offset = offset + i16(bytecount[i:i+2])
                i = i + 2

    file.seek(offset)

    if offset & 1:
        read(1) # padding

    return tile

# --------------------------------------------------------------------
# registry

Image.register_open("PSD", PsdImageFile, _accept)

Image.register_extension("PSD", ".psd")