This image was encoded with png.py.
- True colours
- 8/16 bits depth
- w/ or w/o alpha channel
- Several filter types:
0. none
- sub
- up
- avg
- paeth
- Works with Python 3 (untested with Python 2, so you can probably use the PIL or pypng).
It doesn't aim to implement the full standard. The goal is rather to have a simple/quick/handy png module to output images. (That's something I never really understood, despite having an awseome standard library, Python doesn't provide anything to produce images.)
None, everything is done using the standard library (thanks to the io, struct & zlib modules).
See the output of pydoc png:
Help on module png:
NAME
png
DESCRIPTION
This module contains only one important class: PNG which
may be used to encode image into a PNG bytestring.
Assuming that you have a variable data which is a 2-dimension
list containing tuples, e.g:
>>> import png
>>> data = [[(0xff, 0x00, 0xff), (0x00, 0xff, 0xff)]]
>>> writer = png.PNG(width=2, height=1)
>>> writer.bit_depth = 8
>>> with open('out.png', 'wb') as f:
... f.write(writer.bytes(data))
...
70
>>>
Produce a 2x1 PNG in out.png with the left most pixel 0xff00ff and
the rightmost one 0x00ffff.
CLASSES
builtins.Exception(builtins.BaseException)
PNGException
builtins.object
PNG
class PNG(builtins.object)
| This class is used to encode an image into a PNG.
|
| Implements:
| * True colours
| * w/ or w/o alpha channel
| * 8 or 16 bits depth
| * Different filter types (none, sub, up, avg, paeth)
|
| Maybe:
| * Interlacing
| * Split compressed in multiple IDAT chunks, easy to do, but useful?
| Waste of space?
|
| Won't be implemented:
| * B&W images
| * Indexed colours (PLTE chunk)
| * Optionnal headers (e.g. tEXt)
|
| http://www.w3.org/TR/PNG/
|
| Methods defined here:
|
| __init__(self, width=None, height=None, alpha=False, bit_depth=8, compression_level=7, filter_type=4)
| Initialize the PNG writer.
|
| Each argument corresponds to its property. So look
| at the properties documentation.
|
| bytes(self, data)
| Return the image represented by data as a PNG byte string.
|
| data: two dimensional array (height, width) where each item is a tuple
| representing the color of the pixel like that:
| (r, g, b) is alpha isn't used
| (r, g, b, a) otherwise.
| r, g, b & a should be >= 0 and < 2 ** bit_depth
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
|
| alpha
| True if the image use the alpha channel. Boolean.
|
| bit_depth
| Number of bits per channel per pixel. 8 or 16.
|
| compression_level
| Compression level of deflate algorithm. Integer between 1 and 9 (both included).
|
| filter_type
| The filter type to use with method 0:
| 0: no filter
| 1: sub
| 2: sup
| 3: average
| 4: paeth
|
| height
| Height of the image to encode. Positive integer.
|
| width
| Width of the image to encode. Positive integer.
class PNGException(builtins.Exception)
| Method resolution order:
| PNGException
| builtins.Exception
| builtins.BaseException
| builtins.object
|
| Data descriptors defined here:
|
| __weakref__
| list of weak references to the object (if defined)
|
| ----------------------------------------------------------------------
| Methods inherited from builtins.Exception:
|
| __init__(...)
| x.__init__(...) initializes x; see help(type(x)) for signature
|
| ----------------------------------------------------------------------
| Data and other attributes inherited from builtins.Exception:
|
| __new__ = <built-in method __new__ of type object>
| T.__new__(S, ...) -> a new object with type S, a subtype of T
|
| ----------------------------------------------------------------------
| Methods inherited from builtins.BaseException:
|
| __delattr__(...)
| x.__delattr__('name') <==> del x.name
|
| __getattribute__(...)
| x.__getattribute__('name') <==> x.name
|
| __reduce__(...)
|
| __repr__(...)
| x.__repr__() <==> repr(x)
|
| __setattr__(...)
| x.__setattr__('name', value) <==> x.name = value
|
| __setstate__(...)
|
| __str__(...)
| x.__str__() <==> str(x)
|
| with_traceback(...)
| Exception.with_traceback(tb) --
| set self.__traceback__ to tb and return self.
|
| ----------------------------------------------------------------------
| Data descriptors inherited from builtins.BaseException:
|
| __cause__
| exception cause
|
| __context__
| exception context
|
| __dict__
|
| __traceback__
|
| args
DATA
__all__ = ['PNGException', 'PNG']
AUTHOR
Alexis Daboville
FILE
/home/alexis/stuff/png/png.py
Or the simple example in png.py:
if __name__ == '__main__':
w, h = 256, 256
png = PNG(w, h)
png.alpha = True
png.bit_depth = 8
png.filter_type = 4
data = []
for a in range(h):
row = []
for b in range(w):
r = ~(a & b) & 0xff
g = (a | ~b) & 0xff
b = (~a & b) & 0xff
c = (a ^ b) & 0xff
row.append((r, g, b, c))
data.append(row)
with open('hello.png', 'wb') as f:
f.write(png.bytes(data))