Script doesn't take all the files in the folder

Question

I have compiled a script from different resources. It pads images to specified dimensions.  But I can't get it to process all the images in a folder. It only does one.
Here is the script.
(* IMPORTANT: The with pad color parameter of the pad command does not work in Mac OS 10.5.5. Use4 the SIPS command-line utility instead when padding with a color *)
set this_folder to (choose folder with prompt "Pick the folder containing the files to process:") as string
tell application "System Events"
  set these_files to every file of folder this_folder
end tell
repeat with i from 1 to the count of these_files
  set this_file to (item i of these_files as alias)
  set this_info to info for this_file
end repeat
property target_dimensions : "1024, 768"
property default_color : {0, 0, 0}
set this_path to the quoted form of the POSIX path of this_file
-- get the final dimensions for the padded image
repeat
display dialog "Enter the target dimensions for the padded image:" & return & return & "target width, target height" default answer target_dimensions buttons {"Cancel", "Set Color", "Continue"} default button 3
  copy the result to {text returned:dimensions_string, button returned:button_pressed}
  if the button_pressed is "Set Color" then
  set the default_color to choose color default color default_color
  else
  try
  if the dimensions_string does not contain "," then error
  set AppleScript's text item delimiters to ","
  copy every text item of the dimensions_string to {width_string, height_string}
  set AppleScript's text item delimiters to ""
  set target_W to width_string as integer
  set target_H to height_string as integer
  if target_W is less than 1 then error
  if target_H is less than 1 then error
  set the target_dimensions to (target_W & ", " & target_H) as string
  exit repeat
  on error
  beep
  end try
  end if
end repeat
set the hex_color to text 2 thru -1 of (my RBG_to_HTML(default_color))
try
  tell application "Image Events"
  -- start the Image Events application
  launch
  -- open the image file
  set this_image to open this_file
  -- get dimensions of the image
  copy dimensions of this_image to {W, H}
  -- calculate scaling
  if target_W is greater than target_H then
  if W is greater than H then
  set the scale_length to (W * target_H) / H
  set the scale_length to round scale_length rounding as taught in school
  else
  set the scale_length to target_H
  end if
  else if target_H is greater than target_W then
  if H is greater than W then
  set the scale_length to (H * target_W) / W
  set the scale_length to round scale_length rounding as taught in school
  else
  set the scale_length to target_W
  end if
  else -- square pad area
  set the scale_length to target_H
  end if
  -- perform action
  scale this_image to size scale_length
  (* The with pad color parameter is broken in Mac OS X 10.5.5
  -- perform action
  pad this_image to dimensions {target_W, target_H} with pad color default_color
  -- save the changes
  save this_image with icon
  -- purge the open image data
  close this_image
  end tell
-- The with pad color parameter is not working in 10.5.5 so use the SIPS command-line utitlity instead
do shell script "sips " & this_path & " -p " & target_H & space & target_W & space & "--padColor " & hex_color & space & "-i"
on error error_message
display dialog error_message buttons {"Cancel"} default button 1
end try
on RBG_to_HTML(RGB_values)
-- NOTE: this sub-routine expects the RBG values to be from 0 to 65535
  set the hex_list to {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"}
  set the the hex_value to ""
  repeat with i from 1 to the count of the RGB_values
  set this_value to (item i of the RGB_values) div 256
  if this_value is 256 then set this_value to 255
  set x to item ((this_value div 16) + 1) of the hex_list
  set y to item (((this_value / 16 mod 1) * 16) + 1) of the hex_list
  set the hex_value to (the hex_value & x & y) as string
  end repeat
  return ("#" & the hex_value) as string
end RBG_to_HTML

Answer 1

The problem is this repeat loop
repeat with i from 1 to the count of these_files 
  set this_file to (item i of these_files as alias) 
  set this_info to info for this_file 
end repeat 
It goes through every file in the folder but only sets the variable this_file to one file. When the loop is finished this_file is only pointing to one file, which is the file that will be processed.
A few ways to handle this, the easiest is to move the
end repeat
at line 5 to the just after the do shell script at line 81.