diff --git a/.gitignore b/.gitignore
index 6f5c6fc..7333f34 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,6 @@
 *.mat
 *.swp
 *.swo
-
+bin/
+*.sublime-project
+*.sublime-workspace
diff --git a/Makefile b/Makefile
index be3f2d8..b3a132a 100644
--- a/Makefile
+++ b/Makefile
@@ -5,9 +5,11 @@ CFLAGS = -std=gnu99 -Wall -Wno-unused-parameter -Wno-unused-function -pthread -I
 LDFLAGS = -lpthread -lm
 
 APRILTAG_OBJS = apriltag.o apriltag_quad_thresh.o tag16h5.o tag25h7.o tag25h9.o tag36h10.o tag36h11.o tag36artoolkit.o g2d.o common/zarray.o common/zhash.o common/zmaxheap.o common/unionfind.o common/matd.o common/image_u8.o common/pnm.o common/image_f32.o common/image_u32.o common/workerpool.o common/time_util.o common/svd22.o common/homography.o common/string_util.o common/getopt.o
+BIN_DIR = bin
 
 LIBAPRILTAG := libapriltag.a
 
+
 all: $(LIBAPRILTAG) apriltag_demo
 
 
@@ -17,7 +19,8 @@ $(LIBAPRILTAG): $(APRILTAG_OBJS)
 
 apriltag_demo: apriltag_demo.o
 	@echo "   [$@]"
-	@$(CC) -o $@ apriltag_demo.o $(APRILTAG_OBJS) $(LDFLAGS)
+	mkdir $(BIN_DIR)
+	@$(CC) -o $(BIN_DIR)/$@ apriltag_demo.o $(APRILTAG_OBJS) $(LDFLAGS)
 
 %.o: %.c
 	@echo "   $@"
@@ -25,4 +28,4 @@ apriltag_demo: apriltag_demo.o
 
 .PHONY: clean
 clean:
-	@rm -rf *.o common/*.o $(LIBAPRILTAG) apriltag_demo
+	@rm -rf *.o common/*.o $(LIBAPRILTAG) bin
diff --git a/common/image_u8.c b/common/image_u8.c
index 3bc1c6b..ae9c0c8 100644
--- a/common/image_u8.c
+++ b/common/image_u8.c
@@ -163,6 +163,19 @@ image_u8_t *image_u8_create_from_f32(image_f32_t *fim)
     return im;
 }
 
+image_u8_t *image_u8_create_from_gray(int w, int h, uint8_t *image_matrix)
+{
+    image_u8_t *im = image_u8_create(w, h);
+
+    for (int y = 0; y < h; y++) {
+        for (int x = 0; x < w; x++) {
+            im->buf[y*im->stride + x] = image_matrix[y*im->stride + x];
+        }
+    }
+
+    return im;
+}
+
 
 int image_u8_write_pnm(const image_u8_t *im, const char *path)
 {
diff --git a/common/image_u8.h b/common/image_u8.h
index d9ffa4e..6c0e680 100644
--- a/common/image_u8.h
+++ b/common/image_u8.h
@@ -68,6 +68,7 @@ image_u8_t *image_u8_create(unsigned int width, unsigned int height);
 image_u8_t *image_u8_create_alignment(unsigned int width, unsigned int height, unsigned int alignment);
 image_u8_t *image_u8_create_from_rgb3(int width, int height, uint8_t *rgb, int stride);
 image_u8_t *image_u8_create_from_f32(image_f32_t *fim);
+image_u8_t *image_u8_create_from_gray(int w, int h, uint8_t *image_matrix);
 
 image_u8_t *image_u8_create_from_pnm(const char *path);
     image_u8_t *image_u8_create_from_pnm_alignment(const char *path, int alignment);