diff --git a/src/database.c b/src/database.c
index 8997972..c8720f9 100644
--- a/src/database.c
+++ b/src/database.c
@@ -42,6 +42,8 @@
     return -1; \
   }
 
+const char *imdb_hdr_fmt = "IMDB v%02u, CAPS: %s;";
+
 int db_open(db_t *db, const char *path)
 {
   int init = 0;
@@ -70,7 +72,7 @@ int db_open(db_t *db, const char *path)
 
   if (init) {
     memset(buf, 0x0, IMDB_REC_LEN);
-    snprintf((char *) buf, IMDB_REC_LEN, "DB of image fingerprints (vers %d)", IMDB_VERSION);
+    snprintf((char *) buf, IMDB_REC_LEN, imdb_hdr_fmt, IMDB_VERSION, "M-R");
     DB_SEEK(db, 0);
     DB_WRITE(db, buf, IMDB_REC_LEN);
 
@@ -213,11 +215,11 @@ int db_search(db_t *db, rec_t *sample, float tresh, match_t **matches)
   while (db_rd_blk(db, &blk) > 0) {
     p = blk.data;
     for (i = 0; i < blk.records; i++, p += IMDB_REC_LEN) {
-      t = p + OFF_USED;
+      t = p + REC_OFF_RU;
       if (*t == 0x0) continue;
 
-      t = p + OFF_BITMAP;
-      diff  = (float) bitmap_compare(t, sample->data + OFF_BITMAP);
+      t = p + REC_OFF_BM;
+      diff  = (float) bitmap_compare(t, sample->data + REC_OFF_BM);
       diff /= BITMAP_BITS;
       if (diff > tresh) continue;
 
diff --git a/src/database.h b/src/database.h
index c2de016..4bc2f91 100644
--- a/src/database.h
+++ b/src/database.h
@@ -2,7 +2,7 @@
 #define HAS_DATABASE_H 1
 
 #define IMDB_REC_LEN 48
-#define IMDB_VERSION 1
+#define IMDB_VERSION  2
 #define OPEN_FLAGS O_CREAT | O_RDWR
 
 typedef struct {
@@ -18,21 +18,44 @@ typedef struct {
 } block_t;
 
 /**
-  pos len || description
- - 0   1  -- record is used
- - 1   1  -- must be zero
- - 2  32  -- bitmap, each 2 bytes is row of monochrome image 16x16
- - 33  1  -- level of color R__
- - 34  1  -- level of color _G_
- - 35  1  -- level of color __B
- - 36  11 -- must be zero
- */
+  Database header format - fixed length, 48 bytes
+
+ 0-15 : "IMDB vXX, CAPS: "
+16-23 : capabilities, terminated with ';'
+24-48 : padding with null's
+*/
+
+#define CAP_OFF_BITMAP  0
+#define CAP_OFF_COLORS  1
+#define CAP_OFF_RATIO   2
+/* 3 used, 5 reserved */
+
+/**
+  Database record format - fixed length, 48 bytes
+
+ # | off | len | description
+---+-----+-----+-------------------------------------------------------
+ 1 |   0 |   1 | record is used
+ 2 |   1 |   1 | overall level of color: R--
+ 3 |   2 |   1 | overall level of color: -G-
+ 4 |   3 |   1 | overall level of color: --B
+ 5 |   4 |   2 | image width
+ 6 |   6 |   2 | image height
+ - |   8 |   8 | reserved for future use
+ 7 |  16 |  32 | bitmap, each 2 bytes is row of monochrome image 16x16
+
+field |  12345 6 +       7
+map   |  XRGBWWHH________MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
+sect  |  [     0-15     ][    16-31     ][    32-48     ]
+*/
 
-#define OFF_USED   0
-#define OFF_BITMAP 2
-#define OFF_COLORR 33
-#define OFF_COLORG 34
-#define OFF_COLORB 35
+#define REC_OFF_RU  0 /* record is used */
+#define REC_OFF_CR  1 /* color level: red */
+#define REC_OFF_CG  2 /* color level: green */
+#define REC_OFF_CB  3 /* color level: blue */
+#define REC_OFF_IW  4 /* image width  */
+#define REC_OFF_IH  6 /* image height */
+#define REC_OFF_BM 16 /* image bitmap */
 
 typedef struct {
   uint64_t num;
diff --git a/src/util.c b/src/util.c
index 0636bfe..2924e4c 100644
--- a/src/util.c
+++ b/src/util.c
@@ -78,7 +78,7 @@ int db_usage_map(db_t *db, unsigned short int cols)
   while (db_rd_blk(db, &blk) > 0) {
     p = blk.data;
     for (i = 0; i < blk.records; i++, p += IMDB_REC_LEN) {
-      t = p + OFF_USED;
+      t = p + REC_OFF_RU;
       buf[j] = (*t == 0xFF) ? '1' : '0';
       if (j++ < cols)
         continue;
@@ -111,7 +111,7 @@ int rec_bitmap(db_t *db, rec_t *sample)
   }
 
   for (i = 0; i < 16; i++) {
-    row = *(((uint16_t *) (&sample->data[OFF_BITMAP])) + i);
+    row = *(((uint16_t *) (&sample->data[REC_OFF_BM])) + i);
     for (j = 0; j < 16; j++) {
       putchar((row & 1) == 1 ? '1' : '0');
       row >>= 1;
@@ -156,13 +156,13 @@ int rec_diff(db_t *db, unsigned long a, unsigned long b, unsigned short int show
   }
 
   if (showmap == 0) {
-    diff  = (float) bitmap_compare(&src.data[OFF_BITMAP], &dst.data[OFF_BITMAP]);
+    diff  = (float) bitmap_compare(&src.data[REC_OFF_BM], &dst.data[REC_OFF_BM]);
     diff /= BITMAP_BITS;
     printf("%.2f%%\n", diff * 100);
     return 0;
   }
 
-  bitmap_diffmap(&map[0], src.data + OFF_BITMAP, dst.data + OFF_BITMAP);
+  bitmap_diffmap(&map[0], src.data + REC_OFF_BM, dst.data + REC_OFF_BM);
 
   for (i = 0; i < 16; i++) {
     row = *(((uint16_t *) map) + i);