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A shameless plug: you can give https://github.com/kmike/psd-tools https://github.com/kmike/psd-tools a try. I've read PSD.rb docs and a bit of its code; the im

by kmike84 13y ago

A shameless plug: you can give https://github.com/kmike/psd-tools https://github.com/kmike/psd-tools a try. I've read PSD.rb docs and a bit of its code; the implementation is one of the best and complete I've seen (I've checked almost all PSD reader implementations some time ago). But it seems that psd-tools is mostly on par with PSD.rb. It also have some features that PSD.rb doesn't have, e.g. full support for 'zip-with-prediction' compression, including 32bit layers. Such images are very common in practice, and parsing them is not easy because the compression format is not documented anywhere, and "zip-with-prediction" for 8 and 16bit layers is totally different from "zip-with-prediction" for 32bit layers (for 32bits it is really tricky). If PSD.rb authors are reading this, I urge them to check the decompression code in psd-tools (https://github.com/kmike/psd-tools/blob/master/src/psd_tools/compression.py https://github.com/kmike/psd-tools/blob/master/src/psd_tools...) or in Paint.NET PSD plugin (http://psdplugin.codeplex.com/ http://psdplugin.codeplex.com/) to not waste the time. psd-tools also knows how to export individual layers, and there is an experimental support for exporting layer groups; it seems that this is not implemented in PSD.rb yet. PSD.rb has some features that psd-tools doesn't have, e.g. it parses "Font data" which is really cool and hard because the format is not described anywhere.

tluyben2 13y ago
I checked out psd-tools and it's good. Any chance of you adding their features to yours or vice versa? I know I know, I should do it myself and do a pull request, but just asking if you are planning to?
- kmike84 13y ago
  Unfortunately I'm currently very busy with other projects, so I probably won't implement PSD.rb features myself anytime soon. I'm trying to provide feedback for psd-tools pull requests, merge them and release new psd-tools versions in timely manner; the testing suite also helps here, so you know, pull requests are welcome :) Most improvements over last 6 months came from pull requests submitted by other great people. I think that the "reader" part of library is feature-complete. psd-tools reads all the information, but it doesn't decode all Photoshop data structures (some of them are available only as binary blobs). So I think implementing a PSD.rb feature will most likely involve checking PSD.rb code and decoding a binary blob (already loaded to memory) to a Python data structure.
  - tluyben2 13y ago
    I didn't check your codebase (I just used the library for a few projects a while ago), so you don't have to answer. But if you want to enlighten others as well as me; am I right in thinking that you have a reader while reads the file and then have a 'decoding module' for every blob. So it would be rather straight forward to port from Ruby such a decoding part and plug it into your library?
    - kmike84 13y ago
      Yes, that was the idea. The whole process is divided into 3 stages: reading, decoding and providing "user-facing API": - on "reading" stage PSD file is read and split into binary blobs (I think this part is done); - on "decoding" stage "decoding modules" are called for each binary blob; decoding modules should produce Python data structures that closely resembles internal PSD format; - on "user API" stage decoded data is converted to more convenient format that is easier to work with (e.g. this include building layers hierarchy, and the PSDImage/Layer/etc classes). I hope that providing new decoders will be rather straightforward, and it seems to work this way so far: contributors haven't touched "reader" part, and I haven't touched it for a while as well. But software development is hard, so we can never be sure :)
    - deleted 13y ago
      [deleted]
kellysutton 13y ago
Nice! We should work together.
- kmike84 13y ago
  Thanks! Feel free to steal anything: test PSD files, etc. If you want to implement layer blending in PSD.rb (required if you want to be able to export layer groups as images) then check libpsd C library - I think it has the most sophisticated open-source PSD blending implementation available. Your PSD.rb and https://github.com/layervault/psd-enginedata https://github.com/layervault/psd-enginedata libraries are very nice too; unfortunately I'm busy with other projects now, but maybe somebody will take effort and port PSD.rb features to psd-tools, or I could do this in future - the LayerVault's code will be very helpful.

by kmike84 13y ago

tluyben2 13y ago

I checked out psd-tools and it's good. Any chance of you adding their features to yours or vice versa? I know I know, I should do it myself and do a pull request, but just asking if you are planning to?

kmike84 13y ago
Unfortunately I'm currently very busy with other projects, so I probably won't implement PSD.rb features myself anytime soon. I'm trying to provide feedback for psd-tools pull requests, merge them and release new psd-tools versions in timely manner; the testing suite also helps here, so you know, pull requests are welcome :) Most improvements over last 6 months came from pull requests submitted by other great people. I think that the "reader" part of library is feature-complete. psd-tools reads all the information, but it doesn't decode all Photoshop data structures (some of them are available only as binary blobs). So I think implementing a PSD.rb feature will most likely involve checking PSD.rb code and decoding a binary blob (already loaded to memory) to a Python data structure.
- tluyben2 13y ago
  I didn't check your codebase (I just used the library for a few projects a while ago), so you don't have to answer. But if you want to enlighten others as well as me; am I right in thinking that you have a reader while reads the file and then have a 'decoding module' for every blob. So it would be rather straight forward to port from Ruby such a decoding part and plug it into your library?
  - kmike84 13y ago
    Yes, that was the idea. The whole process is divided into 3 stages: reading, decoding and providing "user-facing API": - on "reading" stage PSD file is read and split into binary blobs (I think this part is done); - on "decoding" stage "decoding modules" are called for each binary blob; decoding modules should produce Python data structures that closely resembles internal PSD format; - on "user API" stage decoded data is converted to more convenient format that is easier to work with (e.g. this include building layers hierarchy, and the PSDImage/Layer/etc classes). I hope that providing new decoders will be rather straightforward, and it seems to work this way so far: contributors haven't touched "reader" part, and I haven't touched it for a while as well. But software development is hard, so we can never be sure :)
  - deleted 13y ago
    [deleted]

kellysutton 13y ago

Nice! We should work together.

kmike84 13y ago
Thanks! Feel free to steal anything: test PSD files, etc. If you want to implement layer blending in PSD.rb (required if you want to be able to export layer groups as images) then check libpsd C library - I think it has the most sophisticated open-source PSD blending implementation available. Your PSD.rb and https://github.com/layervault/psd-enginedata https://github.com/layervault/psd-enginedata libraries are very nice too; unfortunately I'm busy with other projects now, but maybe somebody will take effort and port PSD.rb features to psd-tools, or I could do this in future - the LayerVault's code will be very helpful.