Python package for working with Adobe Photoshop PSD files
Project description
psd-tools is a package for reading Adobe Photoshop PSD files (as described in specification) to Python data structures.
Installation
pip install psd-tools
There are also optional dependencies:
Usage
Load an image:
>>> from psd_tools import PSDImage
>>> psd = PSDImage.load('my_image.psd')
Read image header:
>>> psd.header PsdHeader(number_of_channels=3, height=200, width=100, depth=8, color_mode=RGB)
Access its layers:
>>> psd.layers [<psd_tools.Group: 'Group 2', layer_count=1>, <psd_tools.Group: 'Group 1', layer_count=1>, <psd_tools.Layer: 'Background', size=100x200, x=0, y=0>]
Work with a layer group:
>>> group2 = psd.layers[0] >>> group2.name Group 2 >>> group2.visible True >>> group2.closed False >>> group2.opacity 255 >>> from psd_tools.constants import BlendMode >>> group2.blend_mode == BlendMode.NORMAL True >>> group2.layers [<psd_tools.Layer: 'Shape 2', size=43x62, x=40, y=72)>]
Work with a layer:
>>> layer = group2.layers[0] >>> layer.name Shape 2 >>> layer.bbox BBox(x1=40, y1=72, x2=83, y2=134) >>> layer.width, layer.height (43, 62) >>> layer.visible, layer.opacity, layer.blend_mode (True, 255, u'norm') >>> layer.as_PIL() <PIL.Image.Image image mode=RGBA size=43x62 at ...>
Export a single layer:
>>> layer_image = layer.as_PIL()
>>> layer_image.save('layer.png')
Export the merged image:
>>> merged_image = psd.composite_image()
>>> merged_image.save('my_image.png')
Why yet another PSD reader?
There are existing PSD readers for Python:
PSD reader in PIL is incomplete and contributing to PIL is complicated because of the slow release process, but the main issue with PIL for me is that PIL doesn’t have an API for layer groups.
GIMP is cool, but it is a huge dependency, its PSD parser is not perfect and it is not easy to use GIMP Python plugin from your code.
I also considered contributing to pypsd or psdparse, but they are GPL and I was not totally satisfied with the interface and the code (they are really fine, that’s me having specific style requirements).
So I finally decided to roll out yet another implementation that should be MIT-licensed, systematically based on the specification (it turns out the specs are incomplete and sometimes incorrect though); parser should be implemented as a set of functions; the package should have tests and support both Python 2.x and Python 3.x.
Design overview
The process of handling a PSD file is split into 3 stages:
“Reading”: the file is read and parsed to low-level data structures that closely match the specification. No PIL images are constructed; image resources blocks and additional layer information are extracted but not parsed (they remain just keys with a binary data). The goal is to extract all information from a PSD file.
“Decoding”: image resource blocks and additional layer information blocks are parsed to a more detailed data structures (that are still based on a specification). There are a lot of PSD data types and the library currently doesn’t handle them all, but it should be easy to add the parsing code for the missing PSD data structures if needed.
After (1) and (2) we have an in-memory data structure that closely resembles PSD file; it should be fairly complete but very low-level and not easy to use. So there is a third stage:
“User-facing API”: PIL images of the PSD layers are created and combined to a user-friendly data structure.
Stage separation also means user-facing API may be opinionated: if somebody doesn’t like it then it should possible to build an another API (e.g. without PIL) based on lower-level decoded PSD file.
psd-tools tries not to throw away information from the original PSD file; even if the library can’t parse some info, this info will be likely available somewhere as raw bytes (open a bug if this is not the case). This should make it possible to modify and write PSD files (currently not implemented; contributions are welcome).
Features
Supported:
reading of RGB and RGBA images;
8bit, 16bit and 32bit channels;
all PSD compression methods are supported (not only the most common RAW and RLE);
image ICC profile is taken into account;
most important (imho) 23 image resource types and 12 tagged block types are decoded;
there is an optional Cython extension to make the parsing fast.
Not implemented:
reading of CMYK, Duotone, LAB, etc. images;
many image resource types and tagged blocks are not decoded (they are attached to the result as raw bytes);
this library can’t blend layers together: it is possible to export a single layer and to export a final image, but it is not possible to render e.g. layer group;
the decoding of Descriptor structures is very basic;
the writing of PSD images.
If you need some of unimplemented features then please fire an issue or implement it yourself (pull requests are welcome in this case).
Contributing
Development happens at github and bitbucket:
The main issue tracker is at github: https://github.com/kmike/psd-tools/issues
Feel free to submit ideas, bugs, pull requests (git or hg) or regular patches.
In case of bugs it would be helpful to provide a small PSD file demonstrating the issue; this file may be added to a test suite.
In order to run tests, install tox and type
tox
from the source checkout.
The license is MIT.
Acknowledgments
Thanks to all guys who write PSD parsers: I learned a lot about PSD file structure from the source code of psdparse, GIMP, libpsd and psdparse C library; special thanks to Paint.NET PSD Plugin authors for deciphering the “32bit layer + zip-with-prediction compression” case.
0.5 (2012-11-05)
Support for zip and zip-with-prediction compression methods is added;
support for 16/32bit layers is added;
optional Cython extension for faster zip-with-prediction decompression;
other speed improvements.
0.2 (2012-11-04)
Initial support for 16bit and 32bit PSD files: psd-tools v0.2 can read composite (merged) images for such files and extract information (names, dimensions, hierarchy, etc.) about layers and groups of 16/32bit PSD; extracting image data for distinct layers in 16/32bit PSD files is not suported yet;
better Layer.__repr__;
bbox property for Group.
0.1.4 (2012-11-01)
Packaging is fixed in this release.
0.1.3 (2012-11-01)
Better support for 32bit images (still incomplete);
reader is able to handle “global” tagged layer info blocks that was previously discarded.
0.1.2 (2012-10-30)
warn about 32bit images;
transparency support for composite images.
0.1.1 (2012-10-29)
Initial release (v0.1 had packaging issues).
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