diff --git a/collects/2htdp/private/img-err.rkt b/collects/2htdp/private/img-err.rkt
index 079e59d004..f9fb61169f 100644
--- a/collects/2htdp/private/img-err.rkt
+++ b/collects/2htdp/private/img-err.rkt
@@ -130,9 +130,16 @@
                 'mode
                 i
                 arg)
-     (if (string? arg)
-         (string->symbol arg)
-         arg)]
+     (cond
+       [(or (equal? arg "solid")
+            (equal? arg 'solid))
+        255]
+       [(equal? arg "outline")
+        'outline]
+       [(and (integer? arg)
+             (not (exact? arg)))
+        (inexact->exact arg)]
+       [else arg])]
     [(width height radius radius1 radius2 side-length side-length1 side-length2
             side-a side-b side-c)
      (check-arg fn-name
@@ -278,7 +285,9 @@
 (define (x-place? arg)
   (member arg '("left" left "right" right "middle" middle "center" center "pinhole" pinhole)))
 (define (mode? arg)
-  (member arg '(solid outline "solid" "outline")))
+  (or (member arg '(solid outline "solid" "outline"))
+      (and (integer? arg)
+           (<= 0 arg 255))))
 (define (angle? arg)
   (and (real? arg)
        (< -360 arg 360)))
@@ -307,7 +316,8 @@
 ;; checks the dependent part of the 'color' specification
 (define (check-mode/color-combination fn-name i mode color)
   (cond
-    [(eq? mode 'solid)
+    [(or (eq? mode 'solid)
+         (number? mode))
      (check-arg fn-name (image-color? color) 'image-color i color)]
     [(eq? mode 'outline)
      (void)]))
\ No newline at end of file
diff --git a/collects/2htdp/tests/test-image.rkt b/collects/2htdp/tests/test-image.rkt
index fe26e36a46..1973616d66 100644
--- a/collects/2htdp/tests/test-image.rkt
+++ b/collects/2htdp/tests/test-image.rkt
@@ -688,7 +688,7 @@
 
 (test (normalize-shape (image-shape (ellipse 50 100 'solid 'red)))
       =>
-      (make-translate 25 50 (make-ellipse 50 100 0 'solid "red")))
+      (make-translate 25 50 (make-ellipse 50 100 0 255 "red")))
 
 (test (normalize-shape (make-overlay (image-shape (ellipse 50 100 'solid 'red))
                                      (image-shape (ellipse 50 100 'solid 'blue))))
@@ -702,9 +702,9 @@
                         (image-shape (ellipse 50 100 'solid 'green))))
       =>
       (make-overlay 
-       (make-overlay (make-translate 25 50 (make-ellipse 50 100 0 'solid "red"))
-                     (make-translate 25 50 (make-ellipse 50 100 0 'solid "blue")))
-       (make-translate 25 50 (make-ellipse 50 100 0 'solid "green"))))
+       (make-overlay (make-translate 25 50 (make-ellipse 50 100 0 255 "red"))
+                     (make-translate 25 50 (make-ellipse 50 100 0 255 "blue")))
+       (make-translate 25 50 (make-ellipse 50 100 0 255 "green"))))
 
 (test (normalize-shape (make-overlay
                         (image-shape (ellipse 50 100 'solid 'green))
@@ -712,17 +712,17 @@
                                       (image-shape (ellipse 50 100 'solid 'blue)))))
       =>
       (make-overlay 
-       (make-overlay (make-translate 25 50 (make-ellipse 50 100 0 'solid "green"))
-                     (make-translate 25 50 (make-ellipse 50 100 0 'solid "red")))
-       (make-translate 25 50 (make-ellipse 50 100 0 'solid "blue"))))
+       (make-overlay (make-translate 25 50 (make-ellipse 50 100 0 255 "green"))
+                     (make-translate 25 50 (make-ellipse 50 100 0 255 "red")))
+       (make-translate 25 50 (make-ellipse 50 100 0 255 "blue"))))
 
 (test (normalize-shape (make-translate 100 100 (image-shape (ellipse 50 100 'solid 'blue))))
       =>
-      (make-translate 125 150 (make-ellipse 50 100 0 'solid "blue")))
+      (make-translate 125 150 (make-ellipse 50 100 0 255 "blue")))
 
 (test (normalize-shape (make-translate 10 20 (make-translate 100 100 (image-shape (ellipse 50 100 'solid 'blue)))))
       =>
-      (make-translate 135 170 (make-ellipse 50 100 0 'solid "blue")))
+      (make-translate 135 170 (make-ellipse 50 100 0 255 "blue")))
 
 (test (normalize-shape (image-shape
                         (beside/align 'top
@@ -735,7 +735,7 @@
               (make-point 10 0)
               (make-point 10 10)
               (make-point 0 10))
-        'solid
+        255
         "black")
        (make-crop
         (list (make-point 10 0)
@@ -747,7 +747,7 @@
                (make-point 20 0)
                (make-point 20 10)
                (make-point 10 10))
-         'solid
+         255
          "green"))))
 
 
diff --git a/collects/mrlib/image-core.rkt b/collects/mrlib/image-core.rkt
index 12fe9df586..bdeb509baf 100644
--- a/collects/mrlib/image-core.rkt
+++ b/collects/mrlib/image-core.rkt
@@ -1042,31 +1042,44 @@ the mask bitmap and the original bitmap are all together in a single bytes!
     [else 'smoothed]))
 
 (define (mode-color->pen mode color)
-  (case mode
-    [(outline) 
+  (cond
+    [(eq? mode 'outline)
      (cond
        [(pen? color)
         (pen->pen-obj/cache color)]
        [else
         (send the-pen-list find-or-create-pen (get-color-arg color) 0 'solid 'round 'miter)])]
-    [(solid)
+    [else
      (send the-pen-list find-or-create-pen "black" 1 'transparent)]))
 
 (define (mode-color->brush mode color)
-  (case mode
-    [(outline)
+  (cond
+    [(eq? mode 'outline)
      (send the-brush-list find-or-create-brush "black" 'transparent)]
-    [(solid)
-     (send the-brush-list find-or-create-brush (get-color-arg color) 'solid)]))
+    [else
+     ;; this should only be 'solid if we have an old image from a save file somewhere
+     (define extra-alpha (if (eq? mode 'solid)
+                             255
+                             mode))
+     (send the-brush-list find-or-create-brush (get-color-arg color extra-alpha) 'solid)]))
 
-(define (get-color-arg color)
-  (if (string? color) 
-      color
-      (make-object color% 
-        (color-red color)
-        (color-green color)
-        (color-blue color)
-        (/ (color-alpha color) 255))))
+(define (get-color-arg color [extra-alpha 255])
+  (cond
+    [(string? color) 
+     (define color-obj (or (send the-color-database find-color color)
+                           (send the-color-database find-color "black")))
+     (make-object color%
+       (send color-obj red)
+       (send color-obj green)
+       (send color-obj blue)
+       (/ extra-alpha 255))]
+    [else
+     (make-object color% 
+       (color-red color)
+       (color-green color)
+       (color-blue color)
+       (* (/ (color-alpha color) 255)
+          (/ extra-alpha 255)))]))
 
 
 (define (pen->pen-obj/cache pen)
diff --git a/collects/teachpack/2htdp/scribblings/image.scrbl b/collects/teachpack/2htdp/scribblings/image.scrbl
index 60de9c5525..c6b3964820 100644
--- a/collects/teachpack/2htdp/scribblings/image.scrbl
+++ b/collects/teachpack/2htdp/scribblings/image.scrbl
@@ -53,7 +53,8 @@ Existing images can be rotated, scaled, flipped, and overlaid on top of each oth
   @mode/color-text
   
    @image-examples[(circle 30 "outline" "red")
-                   (circle 20 "solid" "blue")]
+                   (circle 20 "solid" "blue")
+                   (circle 20 100 "blue")]
 
 }
 
@@ -71,8 +72,9 @@ Existing images can be rotated, scaled, flipped, and overlaid on top of each oth
 
   @mode/color-text
   
-  @image-examples[(ellipse 40 20 "outline" "black")
-                  (ellipse 20 40 "solid" "blue")] 
+  @image-examples[(ellipse 60 30 "outline" "black")
+                  (ellipse 30 60 "solid" "blue")
+                  (ellipse 30 60 100 "blue")] 
 }
 
 @defproc[(line [x1 real?] [y1 real?] [pen-or-color (or/c pen? image-color?)]) image?]{
@@ -702,7 +704,13 @@ the @scheme[point-count] argument determines how many points the star has.
                             (ellipse 30 40 "solid" "red")
                             (ellipse 40 30 "solid" "black")
                             (ellipse 50 20 "solid" "red")
-                            (ellipse 60 10 "solid" "black"))]
+                            (ellipse 60 10 "solid" "black"))
+                  (underlay (ellipse 10 60 40 "red")
+                            (ellipse 20 50 40 "red")
+                            (ellipse 30 40 40 "red")
+                            (ellipse 40 30 40 "red")
+                            (ellipse 50 20 40 "red")
+                            (ellipse 60 10 40 "red"))]
   
   }
 
@@ -719,7 +727,12 @@ the @scheme[point-count] argument determines how many points the star has.
                                   (rectangle 50 50 "solid" "seagreen")
                                   (rectangle 40 40 "solid" "silver")
                                   (rectangle 30 30 "solid" "seagreen")
-                                  (rectangle 20 20 "solid" "silver"))]
+                                  (rectangle 20 20 "solid" "silver"))
+                  (underlay/align "left" "middle"
+                                  (rectangle 50 50 50 "seagreen")
+                                  (rectangle 40 40 50 "seagreen")
+                                  (rectangle 30 30 50 "seagreen")
+                                  (rectangle 20 20 50 "seagreen"))]
                                   
   
   }
@@ -1195,10 +1208,17 @@ This section lists predicates for the basic structures provided by the image lib
 
 @defproc[(mode? [x any/c]) boolean?]{
  Determines if @racket[x] is a mode suitable for
- constructing images. It can be one of
+ constructing images. 
+ 
+ It can be one of
  @racket['solid], @racket["solid"], @racket['outline],
  or @racket["outline"], indicating if the shape is
  filled in or not.
+ 
+ It can also be an integer between @racket[0] and @racket[255] (inclusive)
+ indicating the transparency of the image. The integer @racket[255] is
+ fully opaque, and is the same as @racket["solid"] (or @racket['solid]).
+ The integer @racket[0] means fully transparent.
 }
 
 @defproc[(image-color? [x any/c]) boolean?]{