JPEG2000-PIL JPEG 2000 (ISO 15444)¶
From the Pillow docs:
New in version Pillow: 2.4.0
PIL reads and writes JPEG 2000 files containing
RGBA data. It can also read files containing
YCbCr data, which it
converts on read into
RGBA depending on whether or not there is
an alpha channel. PIL supports JPEG 2000 raw codestreams (
.j2k files), as
well as boxed JPEG 2000 files (
.jpx files). PIL does not
support files whose components have different sampling frequencies.
When loading, if you set the
mode on the image prior to the
load() method being invoked, you can ask PIL to
convert the image to either
RGBA rather than choosing for
itself. It is also possible to set
reduce to the number of resolutions to
discard (each one reduces the size of the resulting image by a factor of 2),
layers to specify the number of quality layers to load.
save() method supports the following options:
- The image offset, as a tuple of integers, e.g. (16, 16)
- The tile offset, again as a 2-tuple of integers.
- The tile size as a 2-tuple. If not specified, or if set to None, the image will be saved without tiling.
- Either “rates” or “dB” depending on the units you want to use to specify image quality.
- A sequence of numbers, each of which represents either an approximate size reduction (if quality mode is “rates”) or a signal to noise ratio value in decibels. If not specified, defaults to a single layer of full quality.
- The number of different image resolutions to be stored (which corresponds to the number of Discrete Wavelet Transform decompositions plus one).
- The code-block size as a 2-tuple. Minimum size is 4 x 4, maximum is 1024 x 1024, with the additional restriction that no code-block may have more than 4096 coefficients (i.e. the product of the two numbers must be no greater than 4096).
- The precinct size as a 2-tuple. Must be a power of two along both axes, and must be greater than the code-block size.
True, use the lossy Irreversible Color Transformation followed by DWT 9-7. Defaults to
False, which means to use the Reversible Color Transformation with DWT 5-3.
- Controls the progression order; must be one of
"CPRL". The letters stand for Component, Position, Resolution and Layer respectively and control the order of encoding, the idea being that e.g. an image encoded using LRCP mode can have its quality layers decoded as they arrive at the decoder, while one encoded using RLCP mode will have increasing resolutions decoded as they arrive, and so on.
- Set the encoder to produce output compliant with the digital cinema
specifications. The options here are
"cinema2k-24"for 24fps 2K,
"cinema2k-48"for 48fps 2K, and
"cinema4k-24"for 24fps 4K. Note that for compliant 2K files, at least one of your image dimensions must match 2048 x 1080, while for compliant 4K files, at least one of the dimensions must match 4096 x 2160.
To enable JPEG 2000 support, you need to build and install the OpenJPEG library, version 2.0.0 or higher, before building the Python Imaging Library.
Windows users can install the OpenJPEG binaries available on the
OpenJPEG website, but must add them to their PATH in order to use PIL (if
you fail to do this, you will get errors about not being able to load the
Parameters for reading¶
- pilmode : str
From the Pillow documentation:
- ‘L’ (8-bit pixels, grayscale)
- ‘P’ (8-bit pixels, mapped to any other mode using a color palette)
- ‘RGB’ (3x8-bit pixels, true color)
- ‘RGBA’ (4x8-bit pixels, true color with transparency mask)
- ‘CMYK’ (4x8-bit pixels, color separation)
- ‘YCbCr’ (3x8-bit pixels, color video format)
- ‘I’ (32-bit signed integer pixels)
- ‘F’ (32-bit floating point pixels)
PIL also provides limited support for a few special modes, including ‘LA’ (‘L’ with alpha), ‘RGBX’ (true color with padding) and ‘RGBa’ (true color with premultiplied alpha).
When translating a color image to grayscale (mode ‘L’, ‘I’ or ‘F’), the library uses the ITU-R 601-2 luma transform:
L = R * 299/1000 + G * 587/1000 + B * 114/1000
- as_gray : bool
- If True, the image is converted using mode ‘F’. When mode is not None and as_gray is True, the image is first converted according to mode, and the result is then “flattened” using mode ‘F’.