Encoding and app.doScript

Question

Hi all,
I try to use the function app.doScript to run an applescript. This script use the terminal to look if an picture has an alpha channel.
My function works with files who not contains special char.
Has some one an idea to correct this bug?
I become the following error:
set result to do shell script "sips -g hasAlpha '/Users/bastieneichenberger/Desktop/indd_resize_script/2013-10-19_17-56-00__test.indd/Lin ks/Capture d’écran 2013-10-05 à 12.05.19.png'"
Warning: /Users/bastieneichenberger/Desktop/indd_resize_script/2013-10-19_17-56-00__test.indd/Link s/Capture d’e<0301>cran 2013-10-05 a<0300> 12.05.19.png not a valid file - skipping
Error 4: no file was specified
Try 'sips --help' for help using this tool
#target indesign
var file_path = "/Users/bastieneichenberger/Desktop/indd_resize_script/2013-10-19_17-56-00__test.indd/Links/Capture d’écran 2013-10-05 à 12.05.19.png"
alert(has_item_alpha_channel (file_path) );
function has_item_alpha_channel (file_path){
    if(File.fs == "Windows"){
        throw new Error("the function has_alpha_channel works only on mac os x");
    var appleScript = "set result to do shell script \"sips -g hasAlpha '"+  file_path +"'\"";
    $.writeln(appleScript);
    var result = app.doScript(appleScript, ScriptLanguage.applescriptLanguage);
    var res = result.match("hasAlpha: yes");
    if(res != null){
        res = true;
    else{
        res = false;
    return res;

Answer 1

You should post in the scripting forum. It looks like you are making things too complicated. You shouldn't need a shell script to check for alpha channels—a list of alpha channels is stored in a placed image's clipping path property.
This AppleScript displays the count of alpha channels in a selected image (you should be able to do the same in JS):
--x returns a list of alpha channels—will return {} if there are none
tell application "Adobe InDesign CS6"
    set x to alpha channel path names of clipping path of selection of active document
    set c to count of x
    display dialog "There are " & c & " alpha channels in the selected image"
end tell