* color.c: implement pipi_threshold().

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2747 92316355-f0b4-4df1-b90c-862c8a59935f

pipi/context.c

@@ -304,6 +304,26 @@ int pipi_command(pipi_context_t *ctx, char const *cmd, ...)
         pipi_free(src);
         ctx->images[ctx->nimages - 1] = dst;
     }
+    else if(!strcmp(cmd, "threshold"))
+    {
+        pipi_image_t *src, *dst;
+        char const *arg;
+        va_list ap;
+        double val;
+
+        if(ctx->nimages < 1)
+            return -1;
+        va_start(ap, cmd);
+        arg = va_arg(ap, char const *);
+        va_end(ap);
+        val = atof(arg);
+        src = ctx->images[ctx->nimages - 1];
+        dst = pipi_threshold(src, val);
+        if(dst == NULL)
+            return -1;
+        pipi_free(src);
+        ctx->images[ctx->nimages - 1] = dst;
+    }
     else if(!strcmp(cmd, "mean"))
     {
         pipi_image_t *dst;

pipi/filter/color.c

@@ -243,3 +243,47 @@ pipi_image_t *pipi_invert(pipi_image_t *src)
     return dst;
 }
 
+pipi_image_t *pipi_threshold(pipi_image_t *src, double val)
+{
+    pipi_image_t *dst;
+    pipi_pixels_t *srcp, *dstp;
+    float *srcdata, *dstdata;
+    int x, y, w, h, gray;
+
+    w = src->w;
+    h = src->h;
+
+    gray = (src->last_modified == PIPI_PIXELS_Y_F);
+
+    srcp = gray ? pipi_getpixels(src, PIPI_PIXELS_Y_F)
+                : pipi_getpixels(src, PIPI_PIXELS_RGBA_F);
+    srcdata = (float *)srcp->pixels;
+
+    dst = pipi_new(w, h);
+    dstp = gray ? pipi_getpixels(dst, PIPI_PIXELS_Y_F)
+                : pipi_getpixels(dst, PIPI_PIXELS_RGBA_F);
+    dstdata = (float *)dstp->pixels;
+
+    for(y = 0; y < h; y++)
+    {
+        for(x = 0; x < w; x++)
+        {
+            if(gray)
+            {
+                dstdata[y * w + x] = srcdata[y * w + x] < val ? 0. : 1.;
+            }
+            else
+            {
+                int d = 4 * (y * w + x);
+
+                dstdata[d] = srcdata[d] < val ? 0. : 1.;
+                dstdata[d + 1] = srcdata[d + 1] < val ? 0. : 1.;
+                dstdata[d + 2] = srcdata[d + 2] < val ? 0. : 1.;
+                dstdata[d + 3] = srcdata[d + 3] < val ? 0. : 1.;
+            }
+        }
+    }
+
+    return dst;
+}
+

pipi/pipi.h

@@ -126,6 +126,7 @@ extern pipi_image_t *pipi_brightness(pipi_image_t *, double);
 extern pipi_image_t *pipi_contrast(pipi_image_t *, double);
 extern pipi_image_t *pipi_autocontrast(pipi_image_t *);
 extern pipi_image_t *pipi_invert(pipi_image_t *);
+extern pipi_image_t *pipi_threshold(pipi_image_t *, double);
 extern pipi_image_t *pipi_median(pipi_image_t *, int);
 extern pipi_image_t *pipi_median_ext(pipi_image_t *, int, int);
 extern pipi_image_t *pipi_dilate(pipi_image_t *);

src/pipi.c

@@ -112,6 +112,14 @@ int main(int argc, char *argv[])
             if(pipi_command(ctx, "invert") != 0)
                 return EXIT_FAILURE;
         }
+        else if(!strcmp(argv[0], "--threshold"))
+        {
+            if(argv[1] == NULL)
+                return EXIT_FAILURE;
+            if(pipi_command(ctx, "threshold", argv[1]) != 0)
+                return EXIT_FAILURE;
+            argv++;
+        }
         else if(!strcmp(argv[0], "--dilate"))
         {
             if(pipi_command(ctx, "dilate") != 0)