G'day karld12,

Welcome to the monastery.

I'm not familiar with Privoxy; however, looking at its User Manual, I think this regex will probably do what you want:

s/\s*<img.*src="[^"]*(?<!\/someimage)\.jpg".*>//gm
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s/\s*<img.*src="http:\/\/(?!images\.google\.com\/)[^>]+>//gm
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Update: My apologies. I originally focussed on the image name but, on rereading your question, I see you want to exclude domains. My original solution is in the spoiler; a more appropriate solution folllows.

Here's my test:

#!/usr/bin/env perl

use strict;
use warnings;

my $html_fragment = <<'END_HTML';
    <img src="http://images.google.com/someimage.jpg" />
    <img src="http://images.google.com/NOTsomeimage.jpg" />
    <img src="http://google.somesite.org/image.jpg" />
    <img src="http://somesite.net/google/image.jpg" />
    <img src="http://anythingelse.com/etc.jpg" />
END_HTML

print "Initial markup:\n";
print $html_fragment;

$html_fragment =~ s/\s*<img.*src="http:\/\/(?!images\.google\.com\/)[^
+>]+>//gm;

print "Modified markup:\n";
print $html_fragment;
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Output:

Initial markup:
    <img src="http://images.google.com/someimage.jpg" />
    <img src="http://images.google.com/NOTsomeimage.jpg" />
    <img src="http://google.somesite.org/image.jpg" />
    <img src="http://somesite.net/google/image.jpg" />
    <img src="http://anythingelse.com/etc.jpg" />
Modified markup:
    <img src="http://images.google.com/someimage.jpg" />
    <img src="http://images.google.com/NOTsomeimage.jpg" />
[download]

If this doesn't work for you, please provide an example of the HTML and indicate actual and expected output.