Thank you. This was the hint I needed. Here a working script:

• for a given term, it searches an image in Wikipedia
• if something is available, it grabs it and prints it in Tk

Maybe somebody can find some inspiration

use strict;
use warnings;
use HTTP::Request;
use LWP::UserAgent;
use JSON::PP;
use LWP::Simple;
use Tk;
use Tk::Photo;
use Tk::JPEG;
use Tk::PNG;
use MIME::Base64;

my $ua = LWP::UserAgent->new;

my $QueryString="wind park";

my $urlImage=getWikiImage($QueryString);

if ($urlImage){
    my $data=grabbingImage($urlImage);
    $data = MIME::Base64::encode_base64($data);
    
    #creating GUI
    my $mw   = new MainWindow();
    my $top  = $mw->Frame()->pack();
    my $img = $mw->Photo(-data => $data);
    my $label = $top->Label(-image => $img)->pack();

    MainLoop;
}

sub getWikiImage{
    my $QueryString=shift;
    print "Querying Wiki for $QueryString\n";
    my $imgUrl;
    
        my $url="https://en.wikipedia.org/w/api.php?action=query&title
+s=" . $QueryString . "&prop=pageimages&format=json&pithumbsize=200";
        my $req = HTTP::Request->new(GET => $url);
        my $res = $ua->request($req);
        
        if ($res->is_success) {
            my $json_text= $res->content;
            my $decoded_json = decode_json( $json_text );
            my @WikiItem = $decoded_json->{'query'}{'pages'};
            foreach my $hash_ref (@WikiItem) {
                foreach (keys %{$hash_ref}) {
                    $imgUrl = ${$hash_ref}{$_}{'thumbnail'}{'source'};
                }
            }
        }
        else {
            print "Error\n";
        }
    print "IMG: $imgUrl \n";
    return $imgUrl;
}

sub grabbingImage{
    my $url=shift;
    print "Grabbing image...\n";

    my $request = new HTTP::Request 'GET', $url;
    my $response = $ua->request($request);
       
      if ($response->is_success) {
        return $response->content;
      } else {
        print $response->error_as_HTML;
        return 'error';
      }
}
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