diff --git a/src/common.h b/src/common.h
index 2544be5..6420f7f 100644
--- a/src/common.h
+++ b/src/common.h
@@ -27,9 +27,10 @@ char *decode_slashdot(struct image *img);
 char *decode_test(struct image *img);
 
 /* image operations */
-struct image *image_load(char *name);
+struct image *image_load(const char *name);
 struct image *image_new(int width, int height);
 void image_free(struct image *img);
+void image_save(struct image *img, const char *name);
 void image_display(struct image *img);
 int getgray(struct image *img, int x, int y, int *g);
 int getpixel(struct image *img, int x, int y, int *r, int *g, int *b);
@@ -39,11 +40,14 @@ int setpixel(struct image *img, int x, int y, int r, int g, int b);
 void filter_flood_fill(struct image *img, int x, int y, int r, int g, int b);
 struct image *filter_fill_holes(struct image *img);
 struct image *filter_dup(struct image *img);
+struct image *filter_black_stuff(struct image *img);
 struct image *filter_detect_lines(struct image *img);
 struct image *filter_equalize(struct image *img, int threshold);
 struct image *filter_trick(struct image *img);
 struct image *filter_smooth(struct image *img);
 struct image *filter_median(struct image *img);
 struct image *filter_contrast(struct image *img);
+struct image *filter_crop(struct image *img,
+                          int xmin, int ymin, int xmax, int ymax);
 int filter_count(struct image *img);
 
diff --git a/src/filters.c b/src/filters.c
index 4cf1cd8..ef9efb4 100644
--- a/src/filters.c
+++ b/src/filters.c
@@ -120,6 +120,46 @@ struct image *filter_fill_holes(struct image *img)
     return dst;
 }
 
+struct image *filter_black_stuff(struct image *img)
+{
+    struct image *dst;
+    int x, y;
+    int r, ra, rb, g, b;
+
+    dst = image_new(img->width, img->height);
+
+    /* Remove vertical stuff */
+    for(y = 0; y < img->height; y++)
+        for(x = 0; x < img->width; x++)
+        {
+            getpixel(img, x, y, &r, &g, &b);
+            setpixel(dst, x, y, r, g, b);
+            if(y > 0 && y < img->height - 1)
+            {
+                getpixel(img, x, y - 1, &ra, &g, &b);
+                getpixel(img, x, y + 1, &rb, &g, &b);
+                if(r < ra && (r - ra) * (r - rb) > 5000)
+                    setpixel(dst, x, y, ra, ra, ra);
+            }
+        }
+
+    /* Remove horizontal stuff */
+    for(y = 0; y < img->height; y++)
+        for(x = 0; x < img->width; x++)
+        {
+            getpixel(img, x, y, &r, &g, &b);
+            if(x > 0 && x < img->width - 1)
+            {
+                getpixel(dst, x - 1, y, &ra, &g, &b);
+                getpixel(dst, x + 1, y, &rb, &g, &b);
+                if(r < ra && (r - ra) * (r - rb) > 5000)
+                    setpixel(dst, x, y, ra, ra, ra);
+            }
+        }
+
+    return dst;
+}
+
 struct image *filter_detect_lines(struct image *img)
 {
     struct image *dst;
@@ -165,15 +205,25 @@ struct image *filter_equalize(struct image *img, int threshold)
     struct image *dst;
     int x, y;
     int r, g, b;
+    int min = 0, max = 255;
 
     dst = image_new(img->width, img->height);
 
+    if(threshold < 0)
+    {
+        min = 255;
+        max = 0;
+        threshold = -threshold;
+    }
+
     for(y = 0; y < img->height; y++)
         for(x = 0; x < img->width; x++)
         {
             getpixel(img, x, y, &r, &g, &b);
-            if(r < threshold) r = 0; else r = 255;
-            setpixel(dst, x, y, r, r, r);
+            if(r < threshold)
+                setpixel(dst, x, y, min, min, min);
+            else
+                setpixel(dst, x, y, max, max, max);
         }
 
     return dst;
@@ -329,6 +379,37 @@ struct image *filter_contrast(struct image *img)
     return dst;
 }
 
+struct image *filter_crop(struct image *img,
+                          int xmin, int ymin, int xmax, int ymax)
+{
+    struct image *dst;
+    int x, y;
+    int r, g, b;
+
+    if(xmin < 0)
+        xmin = 0;
+    if(ymin < 0)
+        ymin = 0;
+    if(xmax >= img->width)
+        xmax = img->width - 1;
+    if(ymax >= img->height)
+        ymax = img->height - 1;
+
+    if(xmin >= xmax || ymin >= ymax)
+        return NULL;
+
+    dst = image_new(xmax - xmin, ymax - ymin);
+
+    for(y = 0; y < dst->height; y++)
+        for(x = 0; x < dst->width; x++)
+        {
+            getpixel(img, xmin + x, ymin + y, &r, &g, &b);
+            setpixel(dst, x, y, r, g, b);
+        }
+
+    return dst;
+}
+
 int filter_count(struct image *img)
 {
     int histo[256];
diff --git a/src/image.c b/src/image.c
index 214e2bf..6725ecb 100644
--- a/src/image.c
+++ b/src/image.c
@@ -26,7 +26,7 @@
 #   error "No imaging library"
 #endif
 
-struct image *image_load(char *name)
+struct image *image_load(const char *name)
 {
     struct image *img;
 #if defined(HAVE_SDL_IMAGE_H)
@@ -76,12 +76,12 @@ struct image *image_new(int width, int height)
     rmask = 0xff000000;
     gmask = 0x00ff0000;
     bmask = 0x0000ff00;
-    amask = 0x000000ff;
+    amask = 0x00000000;
 #   else
     rmask = 0x000000ff;
     gmask = 0x0000ff00;
     bmask = 0x00ff0000;
-    amask = 0xff000000;
+    amask = 0x00000000;
 #   endif
     priv = SDL_CreateRGBSurface(SDL_SWSURFACE, width, height, 32,
                                 rmask, gmask, bmask, amask);
@@ -136,6 +136,18 @@ void image_free(struct image *img)
     free(img);
 }
 
+void image_save(struct image *img, const char *name)
+{
+#if defined(HAVE_SDL_IMAGE_H)
+    SDL_SaveBMP(img->priv, name);
+#elif defined(HAVE_IMLIB2_H)
+    imlib_context_set_image(img->priv);
+    imlib_save_image(name);
+#elif defined(HAVE_CV_H)
+    cvSaveImage(name, img->priv);
+#endif
+}
+
 int getgray(struct image *img, int x, int y, int *g)
 {
     if(x < 0 || y < 0 || x >= img->width || y >= img->height)