AppleScript to convert NEF to JPG preserving Creation Date/Time - image

Question

I have a Nikon camera that outputs great NEF raw files, and not so great JPEG files. I can use the Preview app that came with my Mac OSX 10.6.8 (Snow Leopard) to simply open a NEF and SaveAs JPEG to create a file about 1/6 the size that is virtually indistinguishable from the original NEF.
[EDIT] Here is the final script that works as desired, with comments and some error testing:
(*
AppleScript to convert Nikon raw NEF files into much smaller JPG files.
The JPG files will inherit the file date and time of the source NEF files.
Note that any JPG files in the target folder that have the same name
as a NEF file in that folder, will be overwritten.
*)
-- User selects target folder with NEF files to convert and save there.
set theImageFolder to choose folder with prompt "
Select a folder containing fileⁿ.NEF images to
convert into JPEG images and SaveAs: fileⁿ.JPG"
set theOutputFolder to theImageFolder
-- Finder locates NEF files, ignoring other file types in the target folder.
tell application "Finder"
set theImages to every file of theImageFolder whose name extension is "NEF"
end tell
-- Image Events app processes the images.
tell application "Image Events"
launch
repeat with a from 1 to length of theImages
-- Get file name as text string.
set theImage to file ((item a of theImages) as string)
-- Get date/time of source NEF file.
tell application "Finder" to set fileTimestamp to creation date of theImage
set theImageReference to open theImage
tell theImageReference
set theImageName to name
-- Detect the .NEF extension to replace with .JPG on output.
set savedDelimiters to AppleScript's text item delimiters
-- Split filename string into list, using "." as a delimiter.
set AppleScript's text item delimiters to {"."}
set delimitedList to every text item of theImageName
-- Remove the .NEF extension from the list, if it was there.
ignoring case
--Process only NEF files.
if last item of delimitedList is "NEF" then
set filenameList to items 1 thru -2 of delimitedList
set theImageName to filenameList as string
end if
end ignoring
-- Restore delimiters to default in case it had previously been changed.
set AppleScript's text item delimiters to savedDelimiters
-- Construct full path of file to save, with JPG as output file extension.
set saveImageName to ((theOutputFolder as string) & theImageName & ".JPG")
-- Check if a file with the output JPG file name is already present in the target folder.
tell application "Finder"
if exists file saveImageName then
-- Abort script if user doesn't want to overwrite this file and continue.
beep
if button returned of (display dialog " An identical JPG file is already at:
" & saveImageName & "
Would you like to:" buttons {"Replace it and continue", "Abort"} default button "Abort") is "Abort" then exit repeat
end if
end tell
-- SaveAs the file in JPEG format, leaving the source NEF file unmodified.
set saveImageName to save in saveImageName as JPEG
--Match the output JPG file date/time to that of the NEF source file.
tell application "Finder" to set modification date of saveImageName to fileTimestamp
end tell
end repeat
end tell
tell application "Finder"
display alert "Done. Duplicated selected NEF files in
" & theOutputFolder & "
as JPGs with dates/times matching NEFs."
end tell
Below was my initial attempt to create an AppleScript to spare me the hours it would take to do this manually with the Preview app on my hundreds of NEF files. It works, but the helpful folks on this website helped me to greatly improve it. As you can see from the initial user prompt, I wanted to prompt the user only in the event that an existing JPG file will be replaced. I also wanted to have the output file names be n.JPG rather than n.NEF.jpg and have the output JPG file inherit the original NEF file's Creation Date & Time. I welcomed any suggestions, though since I'd already come this far my preference was to refrain from adding shell scripts and do it all with AppleScript if possible.
set theImageFolder to choose folder with prompt "Note: This script will replace any existing files in the selected folder matching
the name of a NEF file and end in a JPG extension with a new file of that name.
For example, X.NEF will create X.JPG and replace any existing file named X.JPG
that was already in the selected folder (not in any other folders). To begin now,
Select a folder with NEF images to convert into JPEG images:"
set theOutputFolder to theImageFolder
tell application "Finder"
set theImages to every file of theImageFolder whose name extension is "NEF"
end tell
tell application "Image Events"
launch
repeat with a from 1 to length of theImages
set theImage to file ((item a of theImages) as string)
set theImageReference to open theImage
tell theImageReference
set theImageName to name
save in ((theOutputFolder as string) & theImageName & ".JPG") as JPEG
end tell
end repeat
end tell
tell application "Finder"
display alert "Done. All NEF files in the selected folder have been duplicated in JPEG format."
end tell

Answer 1

Thank you so much, Atomic Toothbrush!
I can't seem to insert a blank line to a Comment or mark as Code here without it saving the Comment, so here's a followup as an Answer. Really it's more of a revised Question. :}
Seems to me it's very close to working as hoped. I replaced the code inside the Repeat section with the fascinating snippet you suggested, though I don't yet fully understand the tricks it's doing. With one file in the target folder the script aborts highlighting the word "alias" with this message:
error "File Art:Users:me:Desktop:scriptTest:-file:DSC_2070.JPG wasn’t found." number -43 from "Art:Users:me:Desktop:scriptTest:-file:DSC_2070.JPG"
With two files in the target folder and the "as alias" removed, it creates DSC_2070.JPG just fine but doesn't change the mod date and aborts with this message:
error "Can’t set modification date of \"Art:Users:me:Desktop:scriptTest:-file:DSC_2070.JPG\" to date \"Wednesday, August 28, 2013 1:03:29 PM\"." number -10006 from modification date of "Art:Users:me:Desktop:scriptTest:-file:DSC_2070.JPG"
If I run it once to create the JPG file as above, then add the "as alias" back in and run it again it does change the date (for both creation and modification!) to match the source file but then aborts highlighting the last Tell inside the Repeat with this message:
error "File Art:Users:me:Desktop:scriptTest:-file:DSC_2070.JPG wasn’t found." number -43 from "Art:Users:me:Desktop:scriptTest:-file:DSC_2070.JPG"
Looks like it's remembering the last file processed because if I rename the file, remove the "as alias" and run it again it aborts highlighting that same last Tell line inside the Repeat with this message referencing the file name that's no longer in the folder:
error "Can’t set modification date of \"Art:Users:me:Desktop:scriptTest:-file:DSC_2070.JPG\" to date \"Wednesday, August 28, 2013 1:14:19 PM\"." number -10006 from modification date of "Art:Users:me:Desktop:scriptTest:-file:DSC_2070.JPG"
Complete script with Repeat string inserted as tested above:
set theImageFolder to choose folder with prompt "Select a folder with NEF images to convert into JPEG images:"
set theOutputFolder to theImageFolder
tell application "Finder"
set theImages to every file of theImageFolder whose name extension is "NEF"
end tell
tell application "Image Events"
launch
repeat with a from 1 to length of theImages
set theImage to file ((item a of theImages) as string)
tell application "Finder" to set fileTimestamp to creation date of theImage
set theImageReference to open theImage
tell theImageReference
set theImageName to name
set savedDelimiters to AppleScript's text item delimiters
set AppleScript's text item delimiters to {"."}
set delimitedList to every text item of theImageName
ignoring case
if last item of delimitedList is "NEF" then
set filenameList to items 1 thru -2 of delimitedList
set theImageName to filenameList as string
end if
end ignoring
set AppleScript's text item delimiters to savedDelimiters
set saveImageName to ((theOutputFolder as string) & theImageName & ".JPG") as alias
save in saveImageName as JPEG
tell application "Finder" to set modification date of saveImageName to fileTimestamp
end tell
end repeat
end tell
tell application "Finder"
display alert "Done. All NEF files in the selected folder have been duplicated in JPEG format with modification date and time changed to match the NEF source file."
end tell

Answer 2

You could also use sips to convert the images and touch -r to change the modification (and creation) times:
for f in *.nef; do jpg="${f%nef}jpg"; sips -s format jpeg -s formatOptions 90 "$f" -o "$jpg"; touch -r "$f" "$jpg"; done
touch -r normally changes only the modification and access times, but it also changes the creation time if the target time is before the original creation time.
If the files have different creation and modification times, you can use SetFile and GetFileInfo:
SetFile -m "$(GetFileInfo -m "$f")" "$jpg"; SetFile -d "$(GetFileInfo -d "$f")" "$jpg"
-m changes the modification time and -d changes the creation time. SetFile and GetFileInfo are part of the command line tools package that can be downloaded from developer.apple.com/downloads or from Xcode's preferences.

Answer 3

From the filename point of view, it sounds like you just need to strip the .NEF extension from the filename. You can do this by turning the filename string into a list, using "." as a delimiter, remove the last item from the list, then reassemble the list to the filename string. I think this should do it (inserted into "repeat" block):
set theImage to file ((item a of theImages) as string)
tell application "Finder" to set fileTimestamp to creation date of theImage
set theImageReference to open theImage
tell theImageReference
set theImageName to name
set savedDelimiters to AppleScript's text item delimiters
-- Split filename string into list, using "." as a delimiter
set AppleScript's text item delimiters to {"."}
set delimitedList to every text item of theImageName
-- Remove the .NEF extension from the list, if it was there
ignoring case
if last item of delimitedList is "NEF" then
set filenameList to items 1 thru -2 of delimitedList
set theImageName to filenameList as string
end if
end ignoring
-- Restore delimiters to default in case of other users
set AppleScript's text item delimiters to savedDelimiters
-- Construct full path of file to save
set saveImageName to ((theOutputFolder as string) & theImageName & ".JPG")
-- Check for file existence
tell application "Finder"
if exists file saveImageName then
-- Check with user - skip to the next file if user doesn't want to overwrite
if button returned of (display dialog saveImageName & " already exists. Overwrite?" buttons {"Yes", "No"}) is "No" then exit repeat
end if
end tell
-- Save the file
set saveImageName to save in saveImageName as JPEG
-- Fiddle the timestamp of the saved file
tell application "Finder" to set modification date of saveImageName to fileTimestamp
end tell
Note I don't think you can easily change t)he creation date on the .JPG file (it is a r/o property in the finder dictionary. The best I can do is set the modification date of the .JPG file to the creation date of the .NEF file.