Extract layers from PSD with ImageMagick, preserving layout

Question

I'm using ImageMagick to extract layers from a PSD, and it gets them all out fine with:

convert image.psd image-%d.png

But the resulting PNG images are of varying dimensions, depending on the actual contents of the layer. What I'd like is to extract all the layers, but have them all the same size, so that I can easily lay them on top of each other later, and have everything line up just as it did in the original PSD.

If it helps to visualise it, this is what I'm currently getting with the command above:

+----+
|A   |   +-+   +-+
|    | = |A| + |B|
|   B|   +-+   +-+
+----+

And what I want is:

+----+   +----+   +----+
|A   |   |A   |   |    |
|    | = |    | + |    |
|   B|   |    |   |   B|
+----+   +----+   +----+

With the resulting images having a transparent background so that I can do this:

+----+   +----+ 
|A   |   |A   |+
|    | = |    ||
|   B|   |   B||
+----+   +----+|
          +----+

I'm not in any way tied to ImageMagick, so if there's another (preferably command-line) tool that can achieve this, that's fine.

Answer 1

I use this command line to do what are describing:

convert.exe <filename>.psd -set dispose Background -coalesce <outfilename>.png

Answer 2

Type this to extract the layer number 2 from a PSD file:

convert             \
  <filename>.psd[0] \
  <filename>.psd[2] \
  \(                    \
     -clone 0           \
     -alpha transparent \
  \)                    \
 -swap 0           \
 +delete           \
 -coalesce         \
 -compose src-over \
 -composite        \
 <extracted-filename>.png

This creates first a transparent canvas with the same size of the PSD file, then combines it with the layer 2 keeping it's original layout (-coalesce)

Answer 3

In the end this is what worked for me:

convert -dispose Background "input.psd" -layers coalesce "output.png"

Credit goes to "snibgo" from the ImageMagick forums.