diff --git a/lemon-completion.sh b/lemon-completion.sh
index 89a228c..eab8b51 100644
--- a/lemon-completion.sh
+++ b/lemon-completion.sh
@@ -98,7 +98,7 @@ _lemon_annuli()
 _lemon_photometry()
 {
     local opts
-    opts="--overwrite --filter --maximum --margin --gain --annuli
+    opts="--overwrite --filter --exclude --maximum --margin --gain --annuli
     --cores --verbose --coordinates --epoch --aperture --annulus --dannulus
     --min-sky --individual-fwhm --aperture-pix --annulus-pix
     --dannulus-pix --snr-percentile --mean --objectk --filterk --datek
diff --git a/photometry.py b/photometry.py
index 58ffa72..53bb901 100644
--- a/photometry.py
+++ b/photometry.py
@@ -234,6 +234,13 @@ def parallel_photometry(args):
                   "to specify more than one filter with which we want to "
                   "work. " + defaults.desc['filter'])
 
+parser.add_option('--exclude', action = 'append', type = 'passband',
+                  dest = 'excluded_filters', default = None,
+                  help = "ignore those FITS files taken in this photometric "
+                  "filter. This option is the opposite of --filter, and may "
+                  "be as well used multiple times in order to specify more "
+                  "than one photometric filter that must be discarded.")
+
 parser.add_option('--maximum', action = 'store', type = 'int',
                   dest = 'maximum', default = defaults.maximum,
                   help = defaults.desc['maximum'])
@@ -498,6 +505,17 @@ def main(arguments = None):
     if not options.uncimgk:
         options.uncimgk = None
 
+    # There is not much point in using --filter and --exclude at the same time:
+    # the former discards all the images not taken in one or more filters, and
+    # the latter discards the images taken in one or more filters. We should
+    # always need to use one approach or the other, but never both at once.
+
+    if options.filters and options.excluded_filters:
+        msg = "%sError. The --filter and --exclude options are incompatible."
+        print msg % style.prefix
+        print style.error_exit_message
+        return 1
+
     # The annuli JSON file (that generated by the annuli command, and specified
     # with the --annuli option) must exist. The use of this file automatically
     # discards whathever was specified with the Aperture Photometry (FWHM and
@@ -783,6 +801,52 @@ def get_date(img):
             percentage = discarded / former_total * 100
             print msg % (discarded, percentage)
 
+    # Now the opposite of --filter: discard those FITS images taken in any of
+    # the photometric filters contained in options.excluded_filters. The code
+    # below is very, very similar to that of --filter, but here we discard the
+    # images that match any of the specified filters, instead of those that do
+    # *not* match any of them.
+
+    if options.excluded_filters:
+
+        msg = "%sDiscarding images taken in any of the following filters:"
+        print msg % style.prefix
+
+        for index, pfilter in enumerate(sorted(options.excluded_filters)):
+            msg = "%s (%d) %s: " % (style.prefix, index + 1, pfilter)
+            images = files[pfilter]
+            if not images:
+                msg += "(no images)"
+            else:
+                percentage = len(images) / len(files) * 100
+                args = len(images), percentage
+                msg += "%d files to discard (%.2f %%)" % args
+            print msg
+
+        sys.stdout.flush()
+
+        discarded = 0
+        for pfilter, images in files.items():
+            if pfilter in options.excluded_filters:
+                discarded += len(images)
+                del files[pfilter]
+
+        if not files:
+            print
+            print "%sError. All images were discarded." % style.prefix
+            print style.error_exit_message
+            return 1
+
+        else:
+            former_total = len(files) + discarded
+            msg = "%s%d images (%.2f %%) discarded,"
+            percentage = discarded / former_total * 100
+            print msg % (style.prefix, discarded, percentage) ,
+
+            msg = "%d (%.2f %%) remain."
+            percentage = len(files) / former_total * 100
+            print msg % (len(files), percentage)
+
     # If a JSON file is specified with --annuli, it must list the photometric
     # parameters for all the filters on which photometry is to be done.
     if json_annuli: