diff --git a/hicolor.h b/hicolor.h
index a77dae7..740eb90 100644
--- a/hicolor.h
+++ b/hicolor.h
@@ -25,6 +25,54 @@
 
 static const uint8_t hicolor_magic[7] = "HiColor";
 
+static const uint8_t hicolor_256_to_32[] = {
+    0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2,
+    3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5,
+    6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8,
+    9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11,
+    11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13,
+    13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15,
+    16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
+    18, 18, 18, 18, 18, 18, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20, 20,
+    20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22,
+    22, 22, 23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24,
+    25, 25, 25, 25, 25, 25, 25, 25, 26, 26, 26, 26, 26, 26, 26, 26, 27, 27,
+    27, 27, 27, 27, 27, 27, 28, 28, 28, 28, 28, 28, 28, 28, 29, 29, 29, 29,
+    29, 29, 29, 29, 30, 30, 30, 30, 30, 30, 30, 30, 31, 31, 31, 31, 31, 31,
+    31, 31
+};
+
+static const uint8_t hicolor_256_to_64[] = {
+    0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5,
+    6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11,
+    11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15,
+    16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20,
+    20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23, 24, 24, 24, 24,
+    25, 25, 25, 25, 26, 26, 26, 26, 27, 27, 27, 27, 28, 28, 28, 28, 29, 29,
+    29, 29, 30, 30, 30, 30, 31, 31, 31, 31, 32, 32, 32, 32, 33, 33, 33, 33,
+    34, 34, 34, 34, 35, 35, 35, 35, 36, 36, 36, 36, 37, 37, 37, 37, 38, 38,
+    38, 38, 39, 39, 39, 39, 40, 40, 40, 40, 41, 41, 41, 41, 42, 42, 42, 42,
+    43, 43, 43, 43, 44, 44, 44, 44, 45, 45, 45, 45, 46, 46, 46, 46, 47, 47,
+    47, 47, 48, 48, 48, 48, 49, 49, 49, 49, 50, 50, 50, 50, 51, 51, 51, 51,
+    52, 52, 52, 52, 53, 53, 53, 53, 54, 54, 54, 54, 55, 55, 55, 55, 56, 56,
+    56, 56, 57, 57, 57, 57, 58, 58, 58, 58, 59, 59, 59, 59, 60, 60, 60, 60,
+    61, 61, 61, 61, 62, 62, 62, 62, 63, 63, 63, 63
+};
+
+static const uint8_t hicolor_32_to_256[] = {
+    0, 8, 16, 24, 33, 41, 49, 57, 66, 74, 82, 90, 99, 107, 115, 123, 132,
+    140, 148, 156, 165, 173, 181, 189, 198, 206, 214, 222, 231, 239, 247,
+    255
+};
+
+static const uint8_t hicolor_64_to_256[] = {
+    0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 65, 69, 73,
+    77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125, 130, 134,
+    138, 142, 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190,
+    195, 199, 203, 207, 211, 215, 219, 223, 227, 231, 235, 239, 243, 247,
+    251, 255
+};
+
 static const double hicolor_bayer[HICOLOR_BAYER_SIZE * HICOLOR_BAYER_SIZE] = {
      0.0/64, 48.0/64, 12.0/64, 60.0/64,  3.0/64, 51.0/64, 15.0/64, 63.0/64,
     32.0/64, 16.0/64, 44.0/64, 28.0/64, 35.0/64, 19.0/64, 47.0/64, 31.0/64,
@@ -191,14 +239,14 @@ hicolor_result hicolor_value_to_rgb(
     switch (version) {
     case HICOLOR_VERSION_5:
         if (value & 0x8000) return HICOLOR_INVALID_VALUE;
-        rgb->r = (value & 0x1f) << 3;
-        rgb->g = (value & 0x3ff) >> (5 - 3);
-        rgb->b = (value & 0x7fff) >> (10 - 3);
+        rgb->r = hicolor_32_to_256[value & 0x1f];
+        rgb->g = hicolor_32_to_256[(value & 0x3ff) >> 5];
+        rgb->b = hicolor_32_to_256[(value & 0x7fff) >> 10];
         return HICOLOR_OK;
     case HICOLOR_VERSION_6:
-        rgb->r = (value & 0x1f) << 3;
-        rgb->g = (value & 0x7ff) >> (5 - 2);
-        rgb->b = value >> (11 - 3);
+        rgb->r = hicolor_32_to_256[value & 0x1f];
+        rgb->g = hicolor_64_to_256[(value & 0x7ff) >> 5];
+        rgb->b = hicolor_32_to_256[value >> 11];
         return HICOLOR_OK;
     default:
         return HICOLOR_UNKNOWN_VERSION;
@@ -213,10 +261,14 @@ hicolor_result hicolor_rgb_to_value(
 {
     switch (version) {
     case HICOLOR_VERSION_5:
-        *value = (rgb.r >> 3) | (rgb.g >> 3 << 5) | (rgb.b >> 3 << 10);
+        *value = hicolor_256_to_32[rgb.r]
+            | hicolor_256_to_32[rgb.g] << 5
+            | hicolor_256_to_32[rgb.b] << 10;
         return HICOLOR_OK;
     case HICOLOR_VERSION_6:
-        *value = (rgb.r >> 3) | (rgb.g >> 2 << 5) | (rgb.b >> 3 << 11);
+        *value = hicolor_256_to_32[rgb.r]
+            | hicolor_256_to_64[rgb.g] << 5
+            | hicolor_256_to_32[rgb.b] << 11;
         return HICOLOR_OK;
     default:
         return HICOLOR_UNKNOWN_VERSION;