AppleScript resize image and save with new name - applescript

Question

I'm calling an Applescript from within FilemakerPro.
These are the things I try to achieve:
An image is stored within a container field.
It stores it's name and path in separate fields.
An Applescript is being activated to perform these actions:
It retrieves the data from FilemakerPro
It checks if there is a folder with the same name as the field "calculate_merk_id"
If not, it creates the folder
It creates a new imagefile which name should have "__small" added to his name after it has been resized to 155 x 134, and stores it in this folder
It creates a new imagefile which name should have "__large" added to his name after it has been resized to 400 x 400, and stores it in this folder
The first error I receive is that it cannot retrieve the dimensions of the image. Furthermore, it won't create my resized images ... Anyone who wants to give me a hand in the right direction, please?
set pad to cell "ServerImagePath" of current record
set filenaam to cell "afbeelding_local_vol_pad" of current record
set foldernaam to cell "calculate_merk_id" of current record
set volle_foldernaam to cell "ServerImageFolder" of current record
set volle_filenaam to cell "ServerImageFile" of current record
set target_small_width to 155
set target_small_height to 134
set target_large_width to 400
set target_large_height to 400
tell application "Finder"
if not exists volle_foldernaam then
make new folder at pad with properties {name: foldernaam}
end if
duplicate filenaam to volle_foldernaam with replacing
tell application "Image Events"
launch
set this_image to filenaam
copy dimensions of this_image to {W, H}
if target_small_width is greater than target_small_height then
if W is greater than H then
set the scale_length to (W * target_small_height) / H
set the scale_length to round scale_length rounding as taught in school
else
set the scale_length to target_small_height
end if
else if target_small_height is greater than target_small_width then
if H is greater than W then
set the scale_length to (H * target_small_with) / W
set the scale length to round scale_length rounding as taught in school
else
set the scale_length to target_small_width
end if
else
set the scale_length to target_small_height
end if
scale this_image to size scale_length
pad this_image to dimensions {target_small_width, target_small_height}
save this_image as this_name & "__small"
close this_image
end tell
end tell

Answer 1

You forgot to open the image
set this_image to filenaam
should be
set this_image to open filenaam

Answer 2

Why not do this natively in FileMaker? FM 12 and later have the GetThumbnail() function. A script could calculate a re-sized image into a global field, then export the image from the global field. Completely cross-platform will work on OSX and Windows, even FileMaker Go.
Set Field [ photo_temp_g ; GetThumbnail ( photo_original ; width ; height ) ]
Commit Record/Request []
Export Field Contents [ photo_temp_g ; “<filename>” ]