Psd.rb (opens in new tab)

Several years ago while writing a PSD parser in javascript, that comment block saved my sanity.

I think that comment itself was posted on HN or somewhere -- I know I've seen it before.

The file spec released by Adobe (http://www.adobe.com/devnet-apps/photoshop/fileformatashtml/) is actually outdated, wrong in some places, and can be incredibly vague at times.

joke: Legal wanted to open-source it, but was vetoed by Engineering.

But seriously, this kind of back-compatibility horror is the hallmark of success, where success means enduring.

Similar to a Word .doc? Who's worked with both, is it Better, or worse?

Most of the work is done, get off your ass and start porting.

as a programming language fan, i've never found anything as productive as ruby. it may not be the fastest language out there, and it may not have a bunch of static safety guarantees, but for exploratory programming it's pretty much unparalleled. if i were tasked with making a psd reader, i'd definitely do it in ruby first and then port it over to whichever language the client called for.

Great, however, that was possible with ImageMagick before. Even more: ImageMagick can extract PSD layers as separate PNGs.

Wow, everything old, is new again ;)

I think with an actual copy of Photoshop, and a little Applescript, this is something you could have done > 15 years ago.

How long did it take to output each PSD (if you have a rough file size for each that would be great to know)

libpsd and PSD.rb both have features that the other doesn't have. For example, PSD.rb parses text/font data, while libpsd can handle images with zip compression.

libpsd was actually a great reference in building PSD.rb, especially since it was correct during the times that the actual file spec was wrong and more explicit in the type of data being read.

I get this feeling with many open source projects, but merges happen much less often than forks.

A shameless plug: you can give 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...) or in Paint.NET PSD plugin (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.

Just use Ruby for this. I prefer Ruby, but there are times I will pick Python instead because it has better libs for what I need to do, e.g. numerical and scientific libs.

yes. this https://github.com/jerem/psdparse

Close: https://github.com/migurski/Blit

You can access ruby code from python ( throuh jython and jruby) and the process is relatively seamless.

or check out psdparse on github ( there are others out in the wild )

I would've liked to see it in Go, but alas.

Use extendscript or the creative suite extension builder SDK.

Look up markupwand.com an YC alumni. The problem is harder than it looks. Now, I am not an expert in PSD format but a PSD that can be automatically converted to HTML has to be specifically formatted. For example, if you merge text layers with image layers, it becomes difficult to extract the information.

There is certainly the potential for that. The library still has a little ways to go until that's possible.

If anything, I think it would be a cool project to build on top of PSD.rb instead of bloating the core library.

CSS Hat gets you part way there: https://csshat.com/

>So, will there be writing .PSD files as well?

Writing PSD files is considerably easier than reading them. To write, you need only support the features you actually use. To read, you must support everything. For example, Photoshop always saves its layers RLE compressed (or it did when I last wrote code to write PSD files, which was about five years ago), but the format supports uncompressed layer data just fine. So if you're just trying to get basic interoperation with Photoshop, you don't have to worry about RLE at all.

>Imagine: upload a .PSD and get back a clean HTML layout + bootstrap_overrides.css

Why would that require writing .PSD files?

To be fair, if you wanted to convert a PSD to HTML the last thing you'd need is Bootstrap.

The library supports some writing, but it's mostly limited to translating/scaling layers.