Greyscale library: * Implement linearisation curve flipping for 1st/2nd Gen iPods (LCD is inverted when backlight is on, so the curve is also inverted). This needs a slight extension of is_backlight_on() functionality in the core. * Thorough recalibration of all reachable greyscale targets, and #ifdef cleanup. * Reduce on-target gamma a bit, because the displayable contrast range of a monochrome/greyscale isn't that high.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@16936 a1c6a512-1295-4272-9138-f99709370657

9 files changed, 313 insertions, 229 deletions

diff --git a/apps/plugin.c b/apps/plugin.c
index b7037139b5..7c3fab1079 100644
--- a/apps/plugin.c
+++ b/apps/plugin.c
@@ -576,6 +576,7 @@ static const struct plugin_api rockbox_api = {
     /* new stuff at the end, sort into place next time
        the API gets incompatible */
 
+    is_backlight_on,
 };
 
 int plugin_load(const char* plugin, void* parameter)
diff --git a/apps/plugin.h b/apps/plugin.h
index 1753272952..cfbd3e72af 100644
--- a/apps/plugin.h
+++ b/apps/plugin.h
@@ -120,7 +120,7 @@
 #define PLUGIN_MAGIC 0x526F634B /* RocK */
 
 /* increase this every time the api struct changes */
-#define PLUGIN_API_VERSION 105
+#define PLUGIN_API_VERSION 106
 
 /* update this to latest version if a change to the api struct breaks
    backwards compatibility (and please take the opportunity to sort in any
@@ -721,7 +721,8 @@ struct plugin_api {
 
     /* new stuff at the end, sort into place next time
        the API gets incompatible */
-
+       
+    bool (*is_backlight_on)(bool ignore_always_off);
 };
 
 /* plugin header */
diff --git a/apps/plugins/lib/grey.h b/apps/plugins/lib/grey.h
index 4298ae3ada..3d5e6d16c4 100644
--- a/apps/plugins/lib/grey.h
+++ b/apps/plugins/lib/grey.h
@@ -120,9 +120,16 @@ void grey_ub_scroll_down(int count);
 
 /*** Internal stuff ***/
 
+/* standard gamma (s23p8) */
+#ifdef SIMULATOR                /* Standard PC gamma */
+#define _GREY_GAMMA ((200<<8)/100)
+#else   /* Target LCDs have a smaller contrast range */
+#define _GREY_GAMMA ((180<<8)/100)  
+#endif
+
 /* flag definitions */
-#define _GREY_RUNNING          0x0001  /* greyscale overlay is running */
-#define _GREY_DEFERRED_UPDATE  0x0002  /* lcd_update() requested */
+#define _GREY_RUNNING          0x8000  /* greyscale overlay is running */
+#define _GREY_DEFERRED_UPDATE  0x4000  /* lcd_update() requested */
 
 /* fast unsigned multiplication (16x16bit->32bit or 32x32bit->32bit,
  * whichever is faster for the architecture) */
diff --git a/apps/plugins/lib/grey_core.c b/apps/plugins/lib/grey_core.c
index 8a30faa5f8..6b196e1aaf 100644
--- a/apps/plugins/lib/grey_core.c
+++ b/apps/plugins/lib/grey_core.c
@@ -33,189 +33,200 @@
 
 #ifndef SIMULATOR
 
-#if CONFIG_LCD == LCD_SSD1815 || CONFIG_LCD == LCD_IFP7XX \
- || CONFIG_LCD == LCD_MROBE100
-/* measured and interpolated curve */
-/* TODO: check for iFP & m:robe 100 */
+#if defined ARCHOS_RECORDER     /* verified */  \
+ || defined ARCHOS_FMRECORDER   /* should be identical */  \
+ || defined ARCHOS_RECORDERV2   /* should be identical */  \
+ || defined ARCHOS_ONDIOFM      /* verified */  \
+ || defined ARCHOS_ONDIOSP      /* verified */
+/* Average measurements of a Recorder v1, an Ondio FM, a backlight-modded 
+ * Ondio FM, and an Ondio SP. */
 static const unsigned char lcdlinear[256] = {
-      0,   3,   5,   8,  11,  13,  16,  18,
-     21,  23,  26,  28,  31,  33,  36,  38,
-     40,  42,  45,  47,  49,  51,  53,  55,
-     57,  59,  60,  62,  64,  66,  67,  69,
-     70,  72,  73,  74,  76,  77,  78,  79,
-     81,  82,  83,  84,  85,  86,  87,  88,
-     88,  89,  90,  91,  92,  92,  93,  94,
-     95,  95,  96,  97,  97,  98,  99,  99,
-    100, 101, 102, 102, 103, 104, 104, 105,
-    106, 106, 107, 107, 108, 109, 109, 110,
-    111, 111, 112, 113, 113, 114, 114, 115,
-    116, 116, 117, 117, 118, 119, 119, 120,
-    120, 121, 121, 122, 122, 123, 123, 124,
-    124, 125, 125, 126, 126, 127, 127, 128,
-    128, 128, 129, 129, 130, 130, 131, 131,
-    132, 132, 133, 133, 133, 134, 134, 135,
-    135, 136, 136, 137, 137, 138, 138, 138,
-    139, 139, 140, 140, 141, 141, 142, 142,
-    143, 143, 144, 144, 145, 145, 146, 146,
-    147, 147, 148, 148, 148, 149, 149, 150,
-    150, 151, 151, 152, 152, 153, 153, 153,
-    154, 154, 155, 155, 156, 156, 157, 157,
-    158, 158, 158, 159, 159, 160, 160, 161,
-    161, 162, 162, 163, 163, 164, 164, 165,
-    165, 166, 167, 167, 168, 168, 169, 169,
-    170, 171, 171, 172, 173, 173, 174, 175,
-    176, 176, 177, 178, 179, 180, 181, 181,
-    182, 183, 184, 185, 186, 188, 189, 190,
-    191, 192, 194, 195, 196, 198, 199, 201,
-    202, 204, 205, 207, 209, 211, 213, 215,
-    217, 219, 222, 224, 226, 229, 231, 234,
-    236, 239, 242, 244, 247, 250, 252, 255
+  5,   8,  10,  12,  14,  16,  18,  20,  22,  24,  26,  28,  29,  31,  33,  35,
+ 37,  39,  40,  42,  43,  45,  46,  48,  49,  50,  51,  53,  54,  55,  57,  58,
+ 59,  60,  61,  62,  63,  64,  65,  66,  67,  68,  68,  69,  70,  71,  71,  72,
+ 73,  74,  74,  75,  76,  77,  77,  78,  79,  79,  80,  80,  81,  81,  82,  82,
+ 83,  84,  84,  85,  86,  86,  87,  87,  88,  88,  89,  89,  90,  90,  91,  91,
+ 92,  92,  93,  93,  94,  94,  95,  95,  96,  96,  97,  98,  98,  99, 100, 100,
+101, 101, 102, 103, 103, 104, 105, 105, 106, 106, 107, 107, 108, 108, 109, 109,
+110, 110, 111, 112, 112, 113, 114, 114, 115, 115, 116, 117, 117, 118, 119, 119,
+120, 120, 121, 122, 123, 123, 124, 125, 126, 126, 127, 128, 129, 129, 130, 131,
+132, 132, 133, 134, 135, 135, 136, 137, 138, 138, 139, 140, 140, 141, 141, 142,
+143, 144, 145, 146, 147, 147, 148, 149, 150, 151, 152, 153, 154, 154, 155, 156,
+157, 158, 159, 160, 161, 161, 162, 163, 164, 165, 166, 167, 168, 168, 169, 170,
+171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 184, 185, 186, 187,
+188, 189, 191, 192, 194, 195, 197, 198, 199, 200, 202, 203, 204, 205, 207, 208,
+209, 210, 212, 213, 215, 216, 218, 219, 220, 221, 222, 223, 225, 226, 227, 228,
+229, 230, 232, 233, 234, 235, 237, 238, 239, 240, 242, 243, 244, 246, 247, 248
 };
-#elif CONFIG_LCD == LCD_S1D15E06
-/* measured and interpolated curve */
+/* The actual LCD scanrate varies a lot with temperature on these targets */
+#define LCD_SCANRATE 67 /* Hz */
+
+#elif defined IAUDIO_M3         /* verified */
+/* Average measurements of 2 iAudio remotes connected to an M3. */
+static const unsigned char lcdlinear[256] = {
+  5,   9,  13,  17,  21,  26,  30,  34,  38,  42,  46,  50,  54,  58,  62,  66,
+ 70,  73,  76,  78,  80,  82,  84,  86,  88,  90,  91,  92,  94,  95,  96,  97,
+ 98,  99,  99, 100, 101, 102, 102, 103, 104, 104, 105, 105, 106, 107, 107, 108,
+109, 109, 110, 110, 111, 111, 112, 112, 113, 113, 114, 114, 115, 115, 116, 116,
+117, 117, 118, 118, 119, 119, 120, 120, 121, 121, 121, 122, 122, 123, 123, 123,
+124, 124, 124, 125, 125, 126, 126, 126, 127, 127, 127, 128, 128, 129, 129, 129,
+130, 130, 131, 131, 132, 132, 133, 133, 134, 134, 134, 135, 135, 136, 136, 136,
+137, 137, 137, 138, 138, 139, 139, 139, 140, 140, 141, 141, 142, 142, 143, 143,
+144, 144, 145, 145, 146, 147, 147, 148, 149, 149, 150, 150, 151, 151, 152, 152,
+153, 153, 154, 154, 155, 155, 156, 156, 157, 157, 158, 158, 159, 160, 160, 161,
+162, 162, 163, 164, 164, 165, 166, 167, 168, 168, 169, 169, 170, 171, 171, 172,
+173, 173, 174, 175, 176, 176, 177, 178, 179, 179, 180, 181, 182, 182, 183, 184,
+185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 198, 199, 200, 201,
+202, 203, 204, 205, 207, 208, 209, 210, 211, 212, 213, 214, 216, 217, 218, 219,
+220, 221, 222, 223, 225, 226, 227, 228, 229, 230, 231, 232, 234, 235, 236, 237,
+238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 249, 250, 251, 252
+};
+/* The actual LCD scanrate is twice as high, but we cannot transfer fast enough
+ * for 150Hz. Even at 75Hz, greyscale display is very smooth. Average from
+ * 2 iAudio remotes. */
+#define LCD_SCANRATE 75 /* Hz */
+
+#elif defined IAUDIO_M5         /* verified */
+/* Measurement of one iAudio M5L */
+static const unsigned char lcdlinear[256] = {
+  4,   6,   8,  10,  11,  13,  15,  17,  19,  21,  22,  24,  25,  27,  28,  30,
+ 32,  33,  35,  36,  37,  39,  40,  42,  43,  44,  45,  46,  48,  49,  50,  51,
+ 52,  52,  53,  54,  55,  55,  56,  57,  58,  58,  59,  60,  61,  61,  62,  63,
+ 64,  64,  65,  65,  66,  66,  67,  67,  68,  68,  69,  70,  70,  71,  72,  72,
+ 73,  73,  74,  75,  75,  76,  77,  77,  78,  78,  79,  79,  80,  80,  81,  81,
+ 82,  82,  83,  84,  84,  85,  86,  86,  87,  87,  88,  89,  89,  90,  91,  91,
+ 92,  92,  93,  93,  94,  94,  95,  95,  96,  96,  97,  98,  98,  99, 100, 100,
+101, 101, 102, 102, 103, 103, 104, 104, 105, 105, 106, 106, 107, 107, 108, 108,
+109, 109, 110, 110, 111, 111, 112, 112, 113, 113, 114, 114, 115, 115, 116, 116,
+117, 117, 118, 119, 119, 120, 121, 121, 122, 122, 123, 124, 124, 125, 126, 126,
+127, 127, 128, 129, 130, 130, 131, 132, 133, 133, 134, 135, 135, 136, 137, 137,
+138, 139, 140, 141, 142, 142, 143, 144, 145, 146, 147, 148, 149, 149, 150, 151,
+152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 163, 164, 165, 167, 168, 169,
+170, 172, 173, 175, 177, 179, 180, 182, 184, 186, 188, 190, 192, 194, 196, 198,
+200, 202, 204, 205, 207, 209, 210, 212, 214, 216, 218, 219, 221, 223, 224, 226,
+228, 230, 231, 233, 235, 236, 237, 239, 241, 243, 244, 246, 248, 249, 250, 252
+};
+#define LCD_SCANRATE 73 /* Hz */
+
+#elif defined IPOD_1G2G         /* verified */
+/* Average measurements of an iPod 1st Gen (0x00010001) and an iPod 2nd Gen
+ * (0x00020000), measured with both backlight off & backlight on (flipped
+ * curves) and medium load (white background when measuring with backlight on),
+ * as the curve is load dependent (the controller's step-up converter doesn't
+ * provide enough juice). Table is for backlight_off state. */
+static const unsigned char lcdlinear[256] = {
+  4,   6,   8,   9,  11,  13,  14,  16,  17,  18,  20,  21,  23,  24,  26,  27,
+ 29,  30,  31,  32,  34,  35,  36,  37,  38,  39,  40,  41,  41,  42,  43,  44,
+ 45,  45,  46,  47,  47,  48,  49,  49,  50,  50,  51,  51,  52,  52,  53,  53,
+ 54,  54,  54,  55,  55,  56,  56,  56,  57,  57,  57,  58,  58,  59,  59,  59,
+ 60,  60,  60,  61,  61,  62,  62,  62,  63,  63,  63,  64,  64,  65,  65,  65,
+ 66,  66,  67,  67,  68,  68,  69,  69,  70,  70,  71,  71,  72,  72,  73,  73,
+ 74,  74,  74,  75,  75,  76,  76,  76,  77,  77,  78,  78,  79,  79,  80,  80,
+ 81,  81,  82,  82,  83,  83,  84,  84,  85,  85,  86,  86,  87,  87,  88,  88,
+ 89,  89,  90,  91,  92,  92,  93,  94,  95,  95,  96,  97,  97,  98,  99,  99,
+100, 100, 101, 102, 102, 103, 104, 104, 105, 105, 106, 107, 107, 108, 109, 109,
+110, 110, 111, 112, 113, 113, 114, 115, 116, 116, 117, 118, 119, 119, 120, 121,
+122, 122, 123, 124, 125, 125, 126, 127, 128, 129, 130, 131, 131, 132, 133, 134,
+135, 137, 138, 139, 141, 142, 144, 145, 146, 147, 149, 150, 151, 152, 154, 155,
+156, 158, 159, 161, 162, 164, 165, 167, 169, 171, 172, 174, 175, 177, 178, 180,
+182, 184, 186, 188, 189, 191, 193, 195, 197, 199, 201, 203, 206, 208, 210, 212,
+214, 217, 219, 221, 224, 226, 229, 231, 233, 236, 238, 240, 243, 245, 247, 250
+};
+/* Average from an iPod 1st Gen and an iPod 2nd Gen */
+#define LCD_SCANRATE 96 /* Hz */
+
+#elif defined IPOD_MINI2G       /* verified */  \
+   || defined IPOD_MINI         /* should be identical */  \
+   || defined IPOD_3G           /* TODO: verify */  \
+   || defined IPOD_4G           /* TODO: verify */
+/* Measurement of one iPod Mini G2 */
 static const unsigned char lcdlinear[256] = {
-      0,   5,  11,  16,  21,  27,  32,  37,
-     42,  47,  51,  56,  60,  64,  68,  72,
-     75,  78,  81,  84,  87,  89,  91,  93,
-     95,  96,  98,  99, 101, 102, 103, 104,
-    105, 106, 107, 108, 109, 110, 111, 111,
-    112, 113, 113, 114, 115, 115, 116, 117,
-    117, 118, 118, 119, 119, 120, 120, 121,
-    121, 122, 122, 123, 123, 124, 124, 125,
-    125, 126, 126, 127, 127, 127, 128, 128,
-    129, 129, 130, 130, 131, 131, 132, 132,
-    133, 133, 134, 134, 135, 135, 136, 136,
-    137, 137, 138, 138, 138, 139, 139, 140,
-    140, 141, 141, 141, 142, 142, 143, 143,
-    143, 144, 144, 145, 145, 145, 146, 146,
-    146, 147, 147, 147, 148, 148, 149, 149,
-    149, 150, 150, 150, 151, 151, 151, 152,
-    152, 153, 153, 153, 154, 154, 155, 155,
-    155, 156, 156, 157, 157, 157, 158, 158,
-    159, 159, 159, 160, 160, 161, 161, 162,
-    162, 162, 163, 163, 164, 164, 164, 165,
-    165, 166, 166, 167, 167, 167, 168, 168,
-    169, 169, 170, 170, 170, 171, 171, 172,
-    172, 173, 173, 174, 174, 175, 175, 176,
-    176, 177, 177, 178, 178, 179, 179, 180,
-    180, 181, 182, 182, 183, 184, 184, 185,
-    186, 186, 187, 188, 188, 189, 190, 191,
-    191, 192, 193, 194, 195, 196, 196, 197,
-    198, 199, 200, 201, 202, 203, 204, 205,
-    206, 207, 208, 209, 210, 211, 213, 214,
-    215, 216, 218, 219, 220, 222, 223, 225,
-    227, 228, 230, 232, 233, 235, 237, 239,
-    241, 243, 245, 247, 249, 251, 253, 255
+  2,   5,   7,  10,  12,  15,  17,  20,  22,  24,  26,  28,  30,  32,  34,  36,
+ 38,  40,  41,  42,  44,  45,  46,  47,  48,  49,  50,  50,  51,  52,  52,  53,
+ 54,  54,  55,  55,  56,  56,  57,  57,  58,  58,  58,  59,  59,  60,  60,  60,
+ 61,  61,  61,  62,  62,  63,  63,  63,  64,  64,  64,  64,  65,  65,  65,  65,
+ 66,  66,  66,  66,  67,  67,  67,  67,  68,  68,  68,  68,  69,  69,  69,  69,
+ 70,  70,  70,  70,  71,  71,  71,  71,  72,  72,  72,  73,  73,  74,  74,  74,
+ 75,  75,  75,  75,  76,  76,  76,  76,  77,  77,  77,  78,  78,  79,  79,  79,
+ 80,  80,  80,  81,  81,  82,  82,  82,  83,  83,  83,  84,  84,  85,  85,  85,
+ 86,  86,  86,  87,  87,  88,  88,  88,  89,  89,  90,  90,  91,  91,  92,  92,
+ 93,  93,  94,  94,  95,  95,  96,  96,  97,  97,  98,  99,  99, 100, 101, 101,
+102, 102, 103, 104, 104, 105, 106, 106, 107, 108, 109, 110, 110, 111, 112, 113,
+114, 115, 115, 116, 117, 118, 118, 119, 120, 121, 121, 122, 123, 124, 124, 125,
+126, 127, 128, 129, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,
+141, 142, 143, 144, 146, 147, 148, 149, 150, 151, 153, 154, 155, 156, 158, 159,
+160, 162, 163, 165, 166, 168, 169, 171, 172, 175, 177, 180, 182, 185, 187, 190,
+192, 196, 199, 203, 206, 210, 213, 217, 220, 223, 227, 230, 234, 238, 242, 246
 };
-#elif (CONFIG_LCD == LCD_IPOD2BPP) || (CONFIG_LCD == LCD_IPODMINI)
-/* measured and interpolated curve for mini LCD */
-/* TODO: verify this curve on the fullsize greyscale LCD */
+/* Average of an iPod Mini G2 and 2 3rd Gen iPods. */
+#define LCD_SCANRATE 87 /* Hz */
+
+#elif defined IRIVER_H100_SERIES /* verified */
+/* Measurement of one Iriver H140 */
 static const unsigned char lcdlinear[256] = {
-      0,   3,   6,   8,  11,  14,  17,  19,
-     22,  24,  27,  29,  32,  34,  36,  38,
-     40,  42,  44,  45,  47,  48,  50,  51,
-     52,  54,  55,  56,  57,  58,  58,  59,
-     60,  61,  62,  62,  63,  64,  64,  65,
-     66,  66,  67,  67,  68,  68,  69,  69,
-     70,  70,  70,  71,  71,  71,  72,  72,
-     73,  73,  73,  74,  74,  74,  74,  75,
-     75,  75,  76,  76,  76,  77,  77,  77,
-     78,  78,  78,  79,  79,  79,  80,  80,
-     80,  80,  81,  81,  81,  82,  82,  82,
-     83,  83,  83,  84,  84,  84,  85,  85,
-     85,  85,  86,  86,  86,  87,  87,  87,
-     87,  88,  88,  88,  89,  89,  89,  89,
-     90,  90,  90,  91,  91,  91,  92,  92,
-     92,  93,  93,  93,  94,  94,  94,  95,
-     95,  96,  96,  96,  97,  97,  98,  98,
-     99,  99,  99, 100, 100, 101, 101, 102,
-    102, 103, 103, 104, 104, 105, 105, 106,
-    106, 107, 107, 108, 108, 109, 109, 110,
-    110, 111, 111, 112, 113, 113, 114, 114,
-    115, 115, 116, 117, 117, 118, 118, 119,
-    120, 120, 121, 122, 122, 123, 124, 124,
-    125, 126, 126, 127, 128, 128, 129, 130,
-    131, 131, 132, 133, 134, 134, 135, 136,
-    137, 138, 139, 140, 141, 142, 143, 144,
-    145, 146, 147, 148, 149, 150, 152, 153,
-    154, 156, 157, 159, 160, 162, 163, 165,
-    167, 168, 170, 172, 174, 176, 178, 180,
-    182, 184, 187, 189, 192, 194, 197, 200,
-    203, 206, 209, 212, 215, 219, 222, 226,
-    229, 233, 236, 240, 244, 248, 251, 255
+  5,   8,  12,  15,  18,  22,  25,  28,  31,  34,  36,  39,  42,  44,  47,  50,
+ 53,  55,  57,  59,  62,  64,  66,  68,  70,  71,  72,  73,  75,  76,  77,  78,
+ 79,  80,  80,  81,  82,  83,  83,  84,  85,  85,  86,  86,  87,  87,  88,  88,
+ 89,  89,  90,  90,  91,  91,  92,  92,  93,  93,  93,  94,  94,  95,  95,  95,
+ 96,  96,  96,  97,  97,  98,  98,  98,  99,  99,  99, 100, 100, 101, 101, 101,
+102, 102, 102, 103, 103, 104, 104, 104, 105, 105, 106, 106, 107, 107, 108, 108,
+109, 109, 109, 110, 110, 111, 111, 111, 112, 112, 113, 113, 114, 114, 115, 115,
+116, 116, 117, 117, 118, 118, 119, 119, 120, 120, 121, 121, 122, 122, 123, 123,
+124, 124, 125, 125, 126, 127, 127, 128, 129, 129, 130, 130, 131, 131, 132, 132,
+133, 133, 134, 135, 135, 136, 137, 137, 138, 138, 139, 139, 140, 140, 141, 141,
+142, 142, 143, 143, 144, 145, 145, 146, 147, 147, 148, 148, 149, 150, 150, 151,
+152, 152, 153, 153, 154, 155, 155, 156, 157, 157, 158, 159, 160, 160, 161, 162,
+163, 164, 165, 166, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177,
+178, 179, 181, 182, 183, 184, 186, 187, 188, 189, 191, 192, 193, 194, 196, 197,
+198, 200, 202, 203, 205, 207, 208, 210, 212, 214, 215, 217, 218, 220, 221, 223,
+224, 226, 228, 229, 231, 233, 235, 236, 238, 240, 241, 242, 244, 245, 246, 248
 };
-#elif CONFIG_LCD == LCD_TL0350A
-/* measured and interpolated curve for iaudio remote */
+#define LCD_SCANRATE 70 /* Hz */
+
+#else  /* not yet calibrated targets - generic linear mapping */
+/* TODO: calibrate iFP7xx
+ * TODO: Olympus m:robe 100 */
 static const unsigned char lcdlinear[256] = {
-      5,   9,  13,  17,  21,  25,  29,  33,
-     36,  39,  42,  45,  48,  51,  54,  57,
-     60,  62,  65,  67,  70,  72,  75,  77,
-     80,  82,  84,  86,  87,  89,  91,  93,
-     94,  95,  96,  97,  97,  98,  99,  99,
-    100, 100, 101, 102, 103, 103, 104, 105,
-    106, 106, 107, 108, 108, 109, 110, 111,
-    112, 112, 113, 113, 114, 114, 115, 115,
-    116, 116, 117, 117, 118, 118, 119, 119,
-    120, 120, 121, 121, 122, 122, 123, 123,
-    124, 124, 124, 125, 125, 126, 126, 126,
-    127, 127, 127, 128, 128, 129, 129, 129,
-    130, 130, 131, 131, 132, 132, 133, 133,
-    134, 134, 135, 135, 136, 136, 137, 137,
-    138, 138, 139, 139, 140, 140, 141, 141,
-    142, 142, 143, 143, 144, 144, 145, 145,
-    146, 146, 147, 147, 148, 149, 149, 150,
-    151, 151, 152, 152, 153, 154, 154, 155,
-    156, 156, 157, 157, 158, 159, 159, 160,
-    161, 161, 162, 163, 164, 164, 165, 166,
-    167, 167, 168, 169, 170, 170, 171, 172,
-    173, 173, 174, 175, 176, 176, 177, 178,
-    179, 179, 180, 181, 182, 182, 183, 184,
-    185, 186, 187, 188, 188, 189, 191, 191,
-    192, 193, 194, 195, 195, 196, 197, 198,
-    199, 200, 201, 202, 203, 204, 205, 206,
-    207, 208, 209, 210, 211, 212, 213, 214,
-    215, 216, 217, 218, 219, 220, 222, 223,
-    224, 225, 226, 227, 228, 229, 230, 231,
-    232, 233, 234, 235, 236, 237, 238, 239,
-    240, 240, 241, 242, 243, 243, 244, 245,
-    246, 246, 247, 248, 249, 250, 251, 252
+  0,   1,   2,   3,   4,   5,   6,   7,   8,   9,  10,  11,  12,  13,  14,  15,
+ 16,  17,  18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,  30,  31,
+ 32,  33,  34,  35,  36,  37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,
+ 48,  49,  50,  51,  52,  53,  54,  55,  56,  57,  58,  59,  60,  61,  62,  63,
+ 64,  65,  66,  67,  68,  69,  70,  71,  72,  73,  74,  75,  76,  77,  78,  79,
+ 80,  81,  82,  83,  84,  85,  86,  87,  88,  89,  90,  91,  92,  93,  94,  95,
+ 96,  97,  98,  99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
+112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127,
+128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143,
+144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
+160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175,
+176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191,
+192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207,
+208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223,
+224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239,
+240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255
 };
+/* generic default */
+#define LCD_SCANRATE 70 /* Hz */
+
 #endif
 #else /* SIMULATOR */
 /* undo a (generic) PC display gamma of 2.0 to simulate target behaviour */
 static const unsigned char lcdlinear[256] = {
-      0,  16,  23,  28,  32,  36,  39,  42,
-     45,  48,  50,  53,  55,  58,  60,  62,
-     64,  66,  68,  70,  71,  73,  75,  77,
-     78,  80,  81,  83,  84,  86,  87,  89,
-     90,  92,  93,  94,  96,  97,  98, 100,
-    101, 102, 103, 105, 106, 107, 108, 109,
-    111, 112, 113, 114, 115, 116, 117, 118,
-    119, 121, 122, 123, 124, 125, 126, 127,
-    128, 129, 130, 131, 132, 133, 134, 135,
-    135, 136, 137, 138, 139, 140, 141, 142,
-    143, 144, 145, 145, 146, 147, 148, 149,
-    150, 151, 151, 152, 153, 154, 155, 156,
-    156, 157, 158, 159, 160, 160, 161, 162,
-    163, 164, 164, 165, 166, 167, 167, 168,
-    169, 170, 170, 171, 172, 173, 173, 174,
-    175, 176, 176, 177, 178, 179, 179, 180,
-    181, 181, 182, 183, 183, 184, 185, 186,
-    186, 187, 188, 188, 189, 190, 190, 191,
-    192, 192, 193, 194, 194, 195, 196, 196,
-    197, 198, 198, 199, 199, 200, 201, 201,
-    202, 203, 203, 204, 204, 205, 206, 206,
-    207, 208, 208, 209, 209, 210, 211, 211,
-    212, 212, 213, 214, 214, 215, 215, 216,
-    217, 217, 218, 218, 219, 220, 220, 221,
-    221, 222, 222, 223, 224, 224, 225, 225,
-    226, 226, 227, 228, 228, 229, 229, 230,
-    230, 231, 231, 232, 233, 233, 234, 234,
-    235, 235, 236, 236, 237, 237, 238, 238,
-    239, 240, 240, 241, 241, 242, 242, 243,
-    243, 244, 244, 245, 245, 246, 246, 247,
-    247, 248, 248, 249, 249, 250, 250, 251,
-    251, 252, 252, 253, 253, 254, 254, 255
+  0,  16,  23,  28,  32,  36,  39,  42,  45,  48,  50,  53,  55,  58,  60,  62,
+ 64,  66,  68,  70,  71,  73,  75,  77,  78,  80,  81,  83,  84,  86,  87,  89,
+ 90,  92,  93,  94,  96,  97,  98, 100, 101, 102, 103, 105, 106, 107, 108, 109,
+111, 112, 113, 114, 115, 116, 117, 118, 119, 121, 122, 123, 124, 125, 126, 127,
+128, 129, 130, 131, 132, 133, 134, 135, 135, 136, 137, 138, 139, 140, 141, 142,
+143, 144, 145, 145, 146, 147, 148, 149, 150, 151, 151, 152, 153, 154, 155, 156,
+156, 157, 158, 159, 160, 160, 161, 162, 163, 164, 164, 165, 166, 167, 167, 168,
+169, 170, 170, 171, 172, 173, 173, 174, 175, 176, 176, 177, 178, 179, 179, 180,
+181, 181, 182, 183, 183, 184, 185, 186, 186, 187, 188, 188, 189, 190, 190, 191,
+192, 192, 193, 194, 194, 195, 196, 196, 197, 198, 198, 199, 199, 200, 201, 201,
+202, 203, 203, 204, 204, 205, 206, 206, 207, 208, 208, 209, 209, 210, 211, 211,
+212, 212, 213, 214, 214, 215, 215, 216, 217, 217, 218, 218, 219, 220, 220, 221,
+221, 222, 222, 223, 224, 224, 225, 225, 226, 226, 227, 228, 228, 229, 229, 230,
+230, 231, 231, 232, 233, 233, 234, 234, 235, 235, 236, 236, 237, 237, 238, 238,
+239, 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 246, 246, 247,
+247, 248, 248, 249, 249, 250, 250, 251, 251, 252, 252, 253, 253, 254, 254, 255
 };
 #endif /* SIMULATOR */
 
@@ -224,12 +235,64 @@ static inline void _deferred_update(void) __attribute__ ((always_inline));
 static int exp_s16p16(int x);
 static int log_s16p16(int x);
 static void grey_screendump_hook(int fd);
+static void fill_gvalues(void);
 #ifdef SIMULATOR
 static unsigned long _grey_get_pixel(int x, int y);
 #else
 static void _timer_isr(void);
 #endif
 
+#if defined(HAVE_BACKLIGHT_INVERSION) && !defined(SIMULATOR)
+static bool backlight_state;
+
+
+static void invert_gvalues(void)
+{
+    unsigned char *val, *end;
+    unsigned char rev_tab[256];
+    unsigned i;
+    unsigned last_i = 0;
+    unsigned x = 0;
+    unsigned last_x;
+    
+    if (_grey_info.flags & GREY_BUFFERED)
+    {
+        fill_gvalues();
+        grey_update();
+    }
+    else /* Unbuffered - need crude reconstruction */
+    {
+        /* Step 1: Calculate a transposed table for undoing the old mapping */
+        for (i = 0; i < 256; i++)
+        {
+            last_x = x;
+            x = _grey_info.gvalue[i];
+            if (x > last_x)
+            {
+                rev_tab[last_x++] = (last_i + i) / 2;
+                while (x > last_x)
+                    rev_tab[last_x++] = i;
+                last_i = i;
+            }
+        }
+        rev_tab[last_x++] = (last_i + 255) / 2;
+        while (256 > last_x)
+            rev_tab[last_x++] = 255;
+
+        /* Step 2: Calculate new mapping */
+        fill_gvalues();
+
+        /* Step 3: Transpose all pixel values */
+        val = _grey_info.values;
+        end = val + _GREY_MULUQ(_grey_info.width, _grey_info.height);
+
+        do
+            *val = _grey_info.gvalue[rev_tab[*val]];
+        while (++val < end);
+    }
+}
+#endif
+
 /* Update LCD areas not covered by the greyscale overlay */
 static inline void _deferred_update(void)
 {
@@ -275,6 +338,16 @@ static unsigned long _grey_get_pixel(int x, int y)
 /* Timer interrupt handler: display next frame */
 static void _timer_isr(void)
 {
+#if defined(HAVE_BACKLIGHT_INVERSION) && !defined(SIMULATOR)
+    bool bls = _grey_info.rb->is_backlight_on(true);
+    
+    if ((backlight_state != bls) && !(_grey_info.flags & GREY_RAWMAPPED))
+    {
+        backlight_state = bls;
+        invert_gvalues();
+        return; /* don't overload this timer slot */
+    }
+#endif
 #if LCD_PIXELFORMAT == HORIZONTAL_PACKING
     _grey_info.rb->lcd_blit_grey_phase(_grey_info.values, _grey_info.phases,
                                        _grey_info.bx, _grey_info.y,
@@ -343,6 +416,26 @@ static int log_s16p16(int x)
     return y;
 }
 
+static void fill_gvalues(void)
+{
+    int i;
+    unsigned data;
+
+#if defined(HAVE_BACKLIGHT_INVERSION) && !defined(SIMULATOR)
+    unsigned imask = backlight_state ? 0xff : 0;
+#else
+    const unsigned imask = 0;
+#endif
+    for (i = 0; i < 256; i++)
+    {
+        data = exp_s16p16((_GREY_GAMMA * log_s16p16(i * 257 + 1)) >> 8) + 128;
+        data = (data - (data >> 8)) >> 8; /* approx. data /= 257 */
+        data = ((lcdlinear[data ^ imask] ^ imask) << 7) + 127;
+        _grey_info.gvalue[i] = (data + (data >> 8)) >> 8;
+                                      /* approx. data / 255 */
+    }
+}
+
 /* Initialise the framework and prepare the greyscale display buffer
 
  arguments:
@@ -449,7 +542,7 @@ bool grey_init(struct plugin_api* newrb, unsigned char *gbuf, long gbuf_size,
     _grey_info.by = 0;
     _grey_info.bheight = bdim;
 #endif
-    _grey_info.flags = 0;
+    _grey_info.flags = features & 0xff;
     _grey_info.fg_brightness = 0;
     _grey_info.bg_brightness = 255;
     _grey_info.drawmode = DRMODE_SOLID;
@@ -458,21 +551,21 @@ bool grey_init(struct plugin_api* newrb, unsigned char *gbuf, long gbuf_size,
     /* precalculate the value -> pattern index conversion table, taking
        linearisation and gamma correction into account */
     if (features & GREY_RAWMAPPED)
+    {
         for (i = 0; i < 256; i++)
         {
             data = i << 7;
             _grey_info.gvalue[i] = (data + (data >> 8)) >> 8;
         }
+    }
     else
-        for (i = 0; i < 256; i++)
-        {
-            data = exp_s16p16(((2<<8) * log_s16p16(i * 257 + 1)) >> 8) + 128;
-            data = (data - (data >> 8)) >> 8; /* approx. data /= 257 */
-            data = (lcdlinear[data] << 7) + 127;
-            _grey_info.gvalue[i] = (data + (data >> 8)) >> 8;
-                                          /* approx. data / 255 */
-        }
-
+    {
+#if defined(HAVE_BACKLIGHT_INVERSION) && !defined(SIMULATOR)
+        backlight_state = _grey_info.rb->is_backlight_on(true);
+#endif
+        fill_gvalues();
+    }
+        
     if (buf_taken)  /* caller requested info about space taken */
         *buf_taken = buftaken;
 
@@ -509,29 +602,8 @@ void grey_show(bool enable)
 #ifdef NEED_BOOST
         _grey_info.rb->cpu_boost(true);
 #endif
-#if CONFIG_LCD == LCD_SSD1815
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 67, 1, _timer_isr);
-#elif CONFIG_LCD == LCD_S1D15E06
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 70, 1, _timer_isr);
-#elif CONFIG_LCD == LCD_IPOD2BPP
-#ifdef IPOD_1G2G
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 96, 1, _timer_isr); /* verified */
-#elif defined IPOD_3G
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 87, 1, _timer_isr); /* verified */
-#else
-        /* FIXME: verify value */
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 80, 1, _timer_isr);
-#endif
-#elif CONFIG_LCD == LCD_IPODMINI
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 88, 1, _timer_isr);
-#elif CONFIG_LCD == LCD_IFP7XX
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 83, 1, _timer_isr);
-#elif CONFIG_LCD == LCD_MROBE100
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 83, 1, _timer_isr); /* not calibrated/tested */
-#elif CONFIG_LCD == LCD_TL0350A
-        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / 75, 1, _timer_isr); /* verified */
-        /* This is half of the actual frame frequency, but 150Hz is too much */
-#endif /* CONFIG_LCD */
+        _grey_info.rb->timer_register(1, NULL, TIMER_FREQ / LCD_SCANRATE, 1,
+                                      _timer_isr);
 #endif /* !SIMULATOR */
         _grey_info.rb->screen_dump_set_hook(grey_screendump_hook);
     }
diff --git a/apps/screen_access.h b/apps/screen_access.h
index 7efa48c423..883e1528dd 100644
--- a/apps/screen_access.h
+++ b/apps/screen_access.h
@@ -151,7 +151,7 @@ struct screen
     void (*update_viewport)(void);
     void (*backlight_on)(void);
     void (*backlight_off)(void);
-    bool (*is_backlight_on)(void);
+    bool (*is_backlight_on)(bool ignore_always_off);
     void (*backlight_set_timeout)(int index);
 };
 
diff --git a/firmware/backlight.c b/firmware/backlight.c
index 0f66fbf574..19e6933fca 100644
--- a/firmware/backlight.c
+++ b/firmware/backlight.c
@@ -631,13 +631,13 @@ void backlight_off(void)
     queue_post(&backlight_queue, BACKLIGHT_OFF, 0);
 }
 
-/* returns true when the backlight is on OR when it's set to always off */
-bool is_backlight_on(void)
+/* returns true when the backlight is on,
+ * and optionally when it's set to always off. */
+bool is_backlight_on(bool ignore_always_off)
 {
-    if (backlight_timer || backlight_timeout <= 0)
-        return true;
-    else
-        return false;
+    return (backlight_timer > 0)   /* countdown */
+        || (backlight_timeout == 0) /* always on */
+        || ((backlight_timeout < 0) && !ignore_always_off);
 }
 
 /* return value in ticks; 0 means always on, <0 means always off */
@@ -752,13 +752,13 @@ int remote_backlight_get_current_timeout(void)
     return remote_backlight_timeout;
 }
 
-/* returns true when the backlight is on OR when it's set to always off */
-bool is_remote_backlight_on(void)
+/* returns true when the backlight is on, and
+ * optionally  when it's set to always off */
+bool is_remote_backlight_on(bool ignore_always_off)
 {
-    if (remote_backlight_timer != 0 || remote_backlight_timeout <= 0)
-        return true;
-    else
-        return false;
+    return (remote_backlight_timer > 0)   /* countdown */
+        || (remote_backlight_timeout == 0) /* always on */
+        || ((remote_backlight_timeout < 0) && !ignore_always_off);
 }
 
 #endif /* HAVE_REMOTE_LCD */
diff --git a/firmware/drivers/button.c b/firmware/drivers/button.c
index d38306b3ca..90ff800c88 100644
--- a/firmware/drivers/button.c
+++ b/firmware/drivers/button.c
@@ -247,9 +247,10 @@ static void button_tick(void)
 #ifdef HAVE_BACKLIGHT
 #ifdef HAVE_REMOTE_LCD
                     if (btn & BUTTON_REMOTE) {
-                        if (!remote_filter_first_keypress || is_remote_backlight_on()
+                        if (!remote_filter_first_keypress 
+                            || is_remote_backlight_on(false)
 #if defined(IRIVER_H100_SERIES) || defined(IRIVER_H300_SERIES)
-                           || (remote_type()==REMOTETYPE_H300_NONLCD)
+                            || (remote_type()==REMOTETYPE_H300_NONLCD)
 #endif
                             )
                             queue_post(&button_queue, btn, data);
@@ -258,9 +259,9 @@ static void button_tick(void)
                     }
                     else
 #endif
-                        if (!filter_first_keypress || is_backlight_on()
+                        if (!filter_first_keypress || is_backlight_on(false)
 #if BUTTON_REMOTE
-                                || (btn&BUTTON_REMOTE)
+                                || (btn & BUTTON_REMOTE)
 #endif
                            )
                             queue_post(&button_queue, btn, data);
diff --git a/firmware/export/backlight.h b/firmware/export/backlight.h
index 3ee46c1485..35c0f86178 100644
--- a/firmware/export/backlight.h
+++ b/firmware/export/backlight.h
@@ -21,7 +21,7 @@
 
 #include "config.h"
 
-bool is_backlight_on(void);
+bool is_backlight_on(bool ignore_always_off);
 void backlight_on(void);
 void backlight_off(void);
 void backlight_set_timeout(int value);
@@ -57,7 +57,7 @@ void remote_backlight_on(void);
 void remote_backlight_off(void);
 void remote_backlight_set_timeout(int value);
 void remote_backlight_set_timeout_plugged(int value);
-bool is_remote_backlight_on(void);
+bool is_remote_backlight_on(bool ignore_always_off);
 
 #ifdef HAS_REMOTE_BUTTON_HOLD
 void remote_backlight_hold_changed(bool rc_hold_button);
diff --git a/uisimulator/sdl/button.c b/uisimulator/sdl/button.c
index 03f7dc1e96..15764da900 100644
--- a/uisimulator/sdl/button.c
+++ b/uisimulator/sdl/button.c
@@ -883,14 +883,16 @@ void button_event(int key, bool pressed)
 #ifdef HAVE_BACKLIGHT
 #ifdef HAVE_REMOTE_LCD
                         if (btn & BUTTON_REMOTE) {
-                            if (!remote_filter_first_keypress || is_remote_backlight_on())
+                            if (!remote_filter_first_keypress 
+                                || is_remote_backlight_on(false))
                                 queue_post(&button_queue, btn, data);
                             else
                                 skip_remote_release = true;
                         }
                         else
 #endif                                    
-                            if (!filter_first_keypress || is_backlight_on())
+                            if (!filter_first_keypress 
+                                || is_backlight_on(false))
                                 queue_post(&button_queue, btn, data);
                             else
                                 skip_release = true;