This info won't be of any use to you as regards remembering what you did to that particular image, but to help in the future, try enabling the
History Log in Photoshop. What this does is record every change you make to an image, either within the image itself (stored as metadata) or in an external log file.
To enable the History Log, select
Edit >
Preferences >
General
In the
History Log part of the dialog, choose where you want to save Log Items (
Metadata,
Text file or
Both). Also make sure that you choose
Detailed from the
Edit Log Items dropdown menu. Click
OK to save your changes. Now History logging is enabled.
To see the History Log, either open up the text file (if you chose that option), or click on
File >
File Info and select
History (if you chose the Metadata option). Image Metadata can also be viewed in Bridge (if you've got
PS CS2).
Here's a snippet from the History Log of an image I just had a play around with:
2006-10-28T10:03:37+01:00 File 57363047.psd opened
Colored Pencil
Colored Pencil Effect: Colored Pencil
Pencil Width: 12
Stroke Pressure: 7
Paper Brightness: 25
Chalk & Charcoal
Chalk & Charcoal Effect: Chalk & Charcoal
Charcoal Area: 6
Chalk Area: 20
Stroke Pressure: 1
Duplicate Layer
Duplicate current layer 2
Blending Change
Set current layer To: layer
Mode: multiply
Master Opacity Change
Set current layer To: layer
Opacity: 50%
2006-10-28T10:10:20+01:00 File 57363047.psd saved
Save
The History Log is just another one of those really useful features in Photoshop that are buried within the program and not many people know about. Anyhow, now the secret's out: hope this helps.