1 files changed, 78 insertions, 0 deletions
diff --git a/Imaging/libImaging/ModeFilter.c b/Imaging/libImaging/ModeFilter.c
new file mode 100644
index 0000000..b3a9045
--- /dev/null
+++ b/Imaging/libImaging/ModeFilter.c
@@ -0,0 +1,78 @@
+/*
+ * The Python Imaging Library
+ * $Id: ModeFilter.c 2134 2004-10-06 08:55:20Z fredrik $
+ *
+ * mode filter
+ *
+ * history:
+ * 2002-06-08 fl    Created (based on code from IFUNC95)
+ * 2004-10-05 fl    Rewritten; use a simpler brute-force algorithm
+ *
+ * Copyright (c) Secret Labs AB 2002-2004.  All rights reserved.
+ *
+ * See the README file for information on usage and redistribution.
+ */
+
+#include "Imaging.h"
+
+Imaging
+ImagingModeFilter(Imaging im, int size)
+{
+    Imaging imOut;
+    int x, y, i;
+    int xx, yy;
+    int maxcount;
+    UINT8 maxpixel;
+    int histogram[256];
+
+    if (!im || im->bands != 1 || im->type != IMAGING_TYPE_UINT8)
+	return (Imaging) ImagingError_ModeError();
+
+    imOut = ImagingNew(im->mode, im->xsize, im->ysize);
+    if (!imOut)
+	return NULL;
+
+    size = size / 2;
+
+    for (y = 0; y < imOut->ysize; y++) {
+        UINT8* out = &IMAGING_PIXEL_L(imOut, 0, y);
+        for (x = 0; x < imOut->xsize; x++) {
+
+            /* calculate histogram over current area */
+
+            /* FIXME: brute force! to improve, update the histogram
+               incrementally.  may also add a "frequent list", like in
+               the old implementation, but I'm not sure that's worth
+               the added complexity... */
+
+            memset(histogram, 0, sizeof(histogram));
+            for (yy = y - size; yy <= y + size; yy++)
+                if (yy >= 0 && yy < imOut->ysize) {
+                    UINT8* in = &IMAGING_PIXEL_L(im, 0, yy);
+                    for (xx = x - size; xx <= x + size; xx++)
+                        if (xx >= 0 && xx < imOut->xsize)
+                            histogram[in[xx]]++;
+                }
+
+            /* find most frequent pixel value in this region */
+            maxpixel = 0;
+            maxcount = histogram[maxpixel];
+            for (i = 1; i < 256; i++)
+                if (histogram[i] > maxcount) {
+                    maxcount = histogram[i];
+                    maxpixel = (UINT8) i;
+                }
+
+            if (maxcount > 2)
+                out[x] = maxpixel;
+            else
+                out[x] = IMAGING_PIXEL_L(im, x, y);
+
+        }
+        
+    }
+
+    ImagingCopyInfo(imOut, im);
+
+    return imOut;
+}