diff --git a/R/VizCombinedMap.R b/R/VizCombinedMap.R
index 484d4efd59ebc4b256c57515a1a2c52ad16fd1b2..55a7ab04c5eb4accd475474077216d7ac2ef50d7 100644
--- a/R/VizCombinedMap.R
+++ b/R/VizCombinedMap.R
@@ -49,8 +49,9 @@
 #'  values that go beyond 'display_range'. Takes the value 'white' by default.
 #'@param mask Optional numeric array with dimensions (latitude, longitude), with 
 #'  values in the range [0, 1], indicating the opacity of the mask over each 
-#'  grid point. Cells with a 0 will result in no mask, whereas cells with a 1 
-#'  will result in a totally opaque superimposed pixel coloured in 'mask_color'.
+#'  grid point. Cells with a 0 will result in a totally opaque superimposed 
+#'  pixel coloured in 'mask_color', whereas cells with a 1 will have no mask and
+#'  remain totally visible.
 #'@param mask_color Colour to be used for the superimposed mask (if specified in 
 #'  'mask'). Takes the value 'grey' by default.
 #'@param col_mask Deprecated. Use 'mask_color' instead.
@@ -504,11 +505,11 @@ VizCombinedMap <- function(maps, lon, lat,
     lonb <- sort(lon, index.return = TRUE)
 
     cols_mask <- sapply(seq(from = 0, to = 1, length.out = 10), 
-                        function(x) adjustcolor(mask_color, alpha.f = x))
+                        function(x) adjustcolor(mask_color, alpha.f = 1 - x))
     image(lonb$x, latb$x, t(mask)[lonb$ix, latb$ix], 
           axes = FALSE, col = cols_mask, 
           breaks = seq(from = 0, to = 1, by = 0.1), 
-          xlab='', ylab='', add = TRUE, xpd = TRUE)
+          xlab = '', ylab = '', add = TRUE, xpd = TRUE)
     if (!exists('coast_color')) {
       coast_color <- 'black'
     }
diff --git a/R/VizEquiMap.R b/R/VizEquiMap.R
index a9058184b1ce5e3f0060a291dfffa94db959535a..d0e489b7cc1eb26b1f767b47794b5a143fa4a47b 100644
--- a/R/VizEquiMap.R
+++ b/R/VizEquiMap.R
@@ -127,9 +127,12 @@
 #'@param dot_size Scale factor for the dots/symbols to be plotted, specified 
 #'  in 'dots'. If a single value is specified, it will be applied to all 
 #'  layers in 'dots'. Takes 1 by default.
-#'@param mask An array with the same dimensions as 'data' of [0, 1] or logical
-#'  indicating the grids to not plot data. The value 0 or FALSE is the point not
-#'  to be plotted.
+#'@param mask An array with the same dimensions as 'data' with values in the 
+#'  range of [0, 1] or logical, indicating the opacity of the mask over each 
+#'  grid point. Cells with a 0 or FALSE will result in a totally opaque 
+#'  superimposed pixel coloured in 'mask_color', whereas cells with a 1 or TRUE 
+#'  will have no mask and remain totally visible. If the array is numeric, values
+#'  between 0 and 1 will have shades of transparency.
 #'@param mask_color Color of the mask. The default value is 'white'.
 #'@param arr_subsamp Subsampling factor to select a subset of arrows in 
 #'  'varu' and 'varv' to be drawn. Only one out of arr_subsamp arrows will 
@@ -865,15 +868,16 @@ VizEquiMap <- function(data, lon, lat, varu = NULL, varv = NULL,
     }
     if (!identical(dim(mask), dim(data))) {
       stop("Parameter 'mask' must have the same dimensions as 'data'.")
-    } else if (is.numeric(mask)) {
-      if (all(mask %in% c(0, 1))) {
-        mask <- array(as.logical(mask), dim = dim(mask))
-      } else {
-        stop("Parameter 'mask' must have only TRUE/FALSE or 0/1.")
+    }
+    
+    if (is.logical(mask)) {
+      if (!all(mask %in% c(TRUE, FALSE))) {
+        stop("Parameter 'mask' must contain only TRUE/FALSE or values in the range [0, 1].")
       }
-    } else if (is.logical(mask)) {
-      if (!all(mask %in% c(T, F))) {
-        stop("Parameter 'mask' must have only TRUE/FALSE or 0/1.")
+      mask <- as.numeric(mask)
+    } else if (is.numeric(mask)) {
+      if (any(mask < 0 | mask > 1, na.rm = TRUE)) {
+        stop("Parameter 'mask' must contain only TRUE/FALSE or values in the range [0, 1].")
       }
     } else {
       stop("Parameter 'mask' must be a logical or numerical array.")
@@ -1287,12 +1291,10 @@ VizEquiMap <- function(data, lon, lat, varu = NULL, varv = NULL,
   #  Adding a mask
   # ~~~~~~~~~~~~~~~
   #
-  if (!is.null(mask)){
-    
-    mask_logical <- as.logical(mask)
-    
-    for (i in 1:length(mask_logical)) {
-      if (!mask_logical[i]) {
+  if (!is.null(mask)) {
+    for (i in 1:length(mask)) {
+      # Partial/fully masked areas
+      if (!is.na(mask[i]) && mask[i] < 1) { 
         
         # Calculate the longitude and latitude indices
         lon_idx <- (i - 1) %% length(lon) + 1
@@ -1317,7 +1319,8 @@ VizEquiMap <- function(data, lon, lat, varu = NULL, varv = NULL,
                           (lat[lat_idx + 1] + lat[lat_idx]) / 2)
         
         # Draw a rectangle over the masked area
-        rect(lon_min, lat_min, lon_max, lat_max, col = mask_color, border = NA)
+        rect(lon_min, lat_min, lon_max, lat_max,
+             col = adjustcolor(mask_color, alpha.f = 1 - mask[i]), border = NA)
       }
     }
   }