diff --git a/include/cammy/image.h b/include/cammy/image.h
index 6b04364..6d271d3 100644
--- a/include/cammy/image.h
+++ b/include/cammy/image.h
@@ -5,6 +5,10 @@
 
 #include <cammy/tile.h>
 
+#define CAMMY_IMAGE_Y_COEFFICIENT_R 0.2126
+#define CAMMY_IMAGE_Y_COEFFICIENT_G 0.7152
+#define CAMMY_IMAGE_Y_COEFFICIENT_B 0.0722
+
 void cammy_image_dither(uint8_t *dest,
                         uint8_t *src,
                         size_t width,
diff --git a/include/cammy/tile.h b/include/cammy/tile.h
index 453f1f7..9ad16f2 100644
--- a/include/cammy/tile.h
+++ b/include/cammy/tile.h
@@ -7,6 +7,12 @@
 #define CAMMY_TILE_WIDTH   8
 #define CAMMY_TILE_HEIGHT  8
 
+#define CAMMY_TILE_INDEX(x, y, stride) \
+    (((y >> 3) * (stride >> 3)) + (x >> 3))
+
+#define CAMMY_TILE_INDEXED(tiles, x, y, stride) \
+    (&tiles[CAMMY_TILE_INDEX(x, y, stride)])
+
 #pragma pack(1)
 #pragma pack(push)
 
diff --git a/src/image.c b/src/image.c
index d829c6f..0446727 100644
--- a/src/image.c
+++ b/src/image.c
@@ -70,9 +70,9 @@ static uint32_t bayer_matrix[256] = {
 };
 
 static uint8_t rgb_to_grayscale(uint8_t r, uint8_t g, uint8_t b) {
-    return (uint8_t)((0.2126 * (float)r)
-                   + (0.7152 * (float)g)
-                   + (0.0722 * (float)b));
+    return (uint8_t)((CAMMY_IMAGE_Y_COEFFICIENT_R * (float)r)
+                   + (CAMMY_IMAGE_Y_COEFFICIENT_G * (float)g)
+                   + (CAMMY_IMAGE_Y_COEFFICIENT_B * (float)b));
 }
 
 static uint8_t rgb_to_tile_2bpp(uint8_t r, uint8_t g, uint8_t b, size_t x, size_t y) {
@@ -89,9 +89,7 @@ static inline uint8_t tile_read(cammy_tile *tiles,
                                 size_t x,
                                 size_t y,
                                 int stride) {
-    size_t index = ((y >> 3) * (stride >> 3)) + (x >> 3);
-
-    cammy_tile *tile = &tiles[index];
+    cammy_tile *tile = CAMMY_TILE_INDEXED(tiles, x, y, stride);
 
     int tile_x = x & 7,
         tile_y = y & 7;
@@ -107,9 +105,7 @@ static inline void tile_write(cammy_tile *tiles,
                               size_t y,
                               int stride,
                               uint8_t value) {
-    size_t index = ((y >> 3) * (stride >> 3)) + (x >> 3);
-
-    cammy_tile *tile = &tiles[index];
+    cammy_tile *tile = CAMMY_TILE_INDEXED(tiles, x, y, stride);
 
     int tile_x = x & 7,
         tile_y = y & 7;