How to remove alpha from bulk images with AppleScript - bash

Question

I have a bulk amount of images, of which i need to remove alpha from each. This is doable from Preview application, but the sheer amount of times i would need to repeat that is way too time consuming.
I have heard about AppleScript and made some feeble attempts at automating the process, currently to no avail.
i am using something like this and then starting a repeat, but it only allows me to loop through one direct folder (also i'm having troubles with menu bar items)
set fl to files of folder POSIX file "/Users/user/Documents/" as alias list
But i have multiple folders within folders which i wish to change an amount of images. the folder structure is like this:
Users/user/folder/ImagesRoot/
in inside ImagesRoot are 3 folders and one txt file. I want to specifically select 2 of the folders called "Icons" and "Screenshots". In "Icons" is 5 images. However "Screenshots" contains 3 subfolders, each with their own 5 images. (can be referred to as "Screensub 1,2,3")
Once receiving the list of images inside such folder, the process would be something like
tell application "Preview"
open the image file
open the file menu
open export...
untick alpha
press save
press replace
close window
end tell
Loop to next one
when looped through all in Icons folder, do all 5 images of each subfolder of screenshot folder
I am told that AppleScript is a good way to do this, but also that bash is a possibility?
However, i have 2% experience with applescript and maybe 4% of bash, and don't know how to approach it.
Any advice or help would be greatly appreciated.
Thanks

Answer 1

As far as I can tell, Preview doesn’t have the ability to change the alpha of a document, even if you enable AppleScripting. In an application that does support it, such as GraphicConverter, this is a fairly simple task:
on open imageFile
tell application "GraphicConverter 9"
open imageFile
tell window 1
set alpha to false
end tell
--save image as needed
end tell
end open
You may find it easier to use Automator. The combination of Get Folder Contents with Repeat for each subfolder found and Alpha Channel set to Remove may be all you need. If you need to exclude some files, Filter Finder Items would do it.
If you want to use Preview, however, you may be able to use System Events. Something like:
on open imageFile
tell application "Preview"
open imageFile
activate
set filename to name of window 1
tell application "System Events"
tell process "Preview"
click menu item "Export…" of menu "File" of menu bar 1
tell sheet 1 of window 1
--rename file
set value of text field 1 to filename & " Alpha Removed"
--uncheck alpha channel
tell checkbox 1 of group 1
click
end tell
--save
click button "Save"
end tell
end tell
end tell
end tell
end open
If you choose the assistive access route, you may find Apple’s help on signing applications useful: http://support.apple.com/kb/HT5914