PCX is a bitmap image format originally used by PC Paintbrush from ZSoft Corporation. Originally, it was a relatively simple 128-byte header + uncompressed bitmap format, but latest versions introduced more complicated palette support and RLE compression.
There's an option to encode 32-bit or 16-bit RGBA pixels, and thus it can potentially include transparency. Theoretically, it's possible to encode resolution or pixel density in the some of the header fields too, but in reality there's no uniform standard for these, so different implementations treat these differently.
PCX format was never made a formal standard. "ZSoft Corporation Technical Reference Manual" for "Image File (.PCX) Format", last updated in 1991, is likely the closest authoritative source.
This page hosts a formal specification of .pcx file format using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = Pcx.from_file("path/to/local/file.pcx")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = Pcx(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.hdr # => get hdr
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import Enum
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 9):
raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))
class Pcx(KaitaiStruct):
"""PCX is a bitmap image format originally used by PC Paintbrush from
ZSoft Corporation. Originally, it was a relatively simple 128-byte
header + uncompressed bitmap format, but latest versions introduced
more complicated palette support and RLE compression.
There's an option to encode 32-bit or 16-bit RGBA pixels, and thus
it can potentially include transparency. Theoretically, it's
possible to encode resolution or pixel density in the some of the
header fields too, but in reality there's no uniform standard for
these, so different implementations treat these differently.
PCX format was never made a formal standard. "ZSoft Corporation
Technical Reference Manual" for "Image File (.PCX) Format", last
updated in 1991, is likely the closest authoritative source.
.. seealso::
Source - https://web.archive.org/web/20100206055706/http://www.qzx.com/pc-gpe/pcx.txt
"""
class Versions(Enum):
v2_5 = 0
v2_8_with_palette = 2
v2_8_without_palette = 3
paintbrush_for_windows = 4
v3_0 = 5
class Encodings(Enum):
rle = 1
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self._raw_hdr = self._io.read_bytes(128)
_io__raw_hdr = KaitaiStream(BytesIO(self._raw_hdr))
self.hdr = Pcx.Header(_io__raw_hdr, self, self._root)
class Header(KaitaiStruct):
"""
.. seealso::
- "ZSoft .PCX FILE HEADER FORMAT" - https://web.archive.org/web/20100206055706/http://www.qzx.com/pc-gpe/pcx.txt
"""
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.magic = self._io.read_bytes(1)
if not self.magic == b"\x0A":
raise kaitaistruct.ValidationNotEqualError(b"\x0A", self.magic, self._io, u"/types/header/seq/0")
self.version = KaitaiStream.resolve_enum(Pcx.Versions, self._io.read_u1())
self.encoding = KaitaiStream.resolve_enum(Pcx.Encodings, self._io.read_u1())
self.bits_per_pixel = self._io.read_u1()
self.img_x_min = self._io.read_u2le()
self.img_y_min = self._io.read_u2le()
self.img_x_max = self._io.read_u2le()
self.img_y_max = self._io.read_u2le()
self.hdpi = self._io.read_u2le()
self.vdpi = self._io.read_u2le()
self.palette_16 = self._io.read_bytes(48)
self.reserved = self._io.read_bytes(1)
if not self.reserved == b"\x00":
raise kaitaistruct.ValidationNotEqualError(b"\x00", self.reserved, self._io, u"/types/header/seq/11")
self.num_planes = self._io.read_u1()
self.bytes_per_line = self._io.read_u2le()
self.palette_info = self._io.read_u2le()
self.h_screen_size = self._io.read_u2le()
self.v_screen_size = self._io.read_u2le()
class TPalette256(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.magic = self._io.read_bytes(1)
if not self.magic == b"\x0C":
raise kaitaistruct.ValidationNotEqualError(b"\x0C", self.magic, self._io, u"/types/t_palette_256/seq/0")
self.colors = []
for i in range(256):
self.colors.append(Pcx.Rgb(self._io, self, self._root))
class Rgb(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
self._io = _io
self._parent = _parent
self._root = _root if _root else self
self._read()
def _read(self):
self.r = self._io.read_u1()
self.g = self._io.read_u1()
self.b = self._io.read_u1()
@property
def palette_256(self):
"""
.. seealso::
- "VGA 256 Color Palette Information" - https://web.archive.org/web/20100206055706/http://www.qzx.com/pc-gpe/pcx.txt
"""
if hasattr(self, '_m_palette_256'):
return self._m_palette_256
if ((self.hdr.version == Pcx.Versions.v3_0) and (self.hdr.bits_per_pixel == 8) and (self.hdr.num_planes == 1)) :
_pos = self._io.pos()
self._io.seek((self._io.size() - 769))
self._m_palette_256 = Pcx.TPalette256(self._io, self, self._root)
self._io.seek(_pos)
return getattr(self, '_m_palette_256', None)