From 919f2b3050c6b92e71e01afa5a233a88ba208a49 Mon Sep 17 00:00:00 2001
From: Andy Koppe <>
Date: Thu, 24 Mar 2022 03:11:56 +0100
Subject: [PATCH] tweak Blue of Helmholtz-Kohlrausch themes (including luminous
 and new kohlrausch)

---
 src/config.c      |  6 +++---
 themes/helmholtz  | 13 ++++++-------
 themes/kohlrausch | 49 +++++++++++++++++++++++++++++++++++++++++++++++
 themes/luminous   | 22 ++++++++++-----------
 4 files changed, 68 insertions(+), 22 deletions(-)
 create mode 100644 themes/kohlrausch

diff --git a/src/config.c b/src/config.c
index 317945ae..93849f3e 100644
--- a/src/config.c
+++ b/src/config.c
@@ -272,8 +272,8 @@ const config default_cfg = {
     [RED_I]          = RGB(216,  36,  51),
     [GREEN_I]        = RGB( 28, 168,   0),
     [YELLOW_I]       = RGB(192, 160,   0),
-    [BLUE_I]         = RGB(  0,  72, 216),
-    [MAGENTA_I]      = RGB(180,  60, 204),
+    [BLUE_I]         = RGB(  0,  55, 220),
+    [MAGENTA_I]      = RGB(177,  72, 198),
     [CYAN_I]         = RGB(  0, 168, 154),
     [WHITE_I]        = RGB(191, 191, 191),
     [BOLD_BLACK_I]   = RGB( 96,  96,  96),
@@ -281,7 +281,7 @@ const config default_cfg = {
     [BOLD_GREEN_I]   = RGB(  0, 244,   0),
     [BOLD_YELLOW_I]  = RGB(240, 240,   0),
     [BOLD_BLUE_I]    = RGB( 85, 170, 255),
-    [BOLD_MAGENTA_I] = RGB(255, 102, 255),
+    [BOLD_MAGENTA_I] = RGB(255, 114, 255),
     [BOLD_CYAN_I]    = RGB(  0, 240, 240),
     [BOLD_WHITE_I]   = RGB(255, 255, 255)
 #endif
diff --git a/themes/helmholtz b/themes/helmholtz
index 314eab97..e355bdb7 100644
--- a/themes/helmholtz
+++ b/themes/helmholtz
@@ -3,9 +3,8 @@
 # The aim of this theme is to provide vibrant colours where the normal and bold
 # levels each have approximately equal brightness. The exception is normal blue,
 # which is somewhat darker than the others as a compromise between readability
-# on a black background and suitability as a background colour. The normal and
-# bold variant of each colour have slightly different hues to help distinguish
-# them.
+# on a black background and suitability as a background colour. The variants of
+# each colour have slightly different hues to help distinguish them.
 #
 # To level the colours, their luminance was calculated as follows:
 # - Gamma-expand the sRGB components by dividing each by 255 and applying the
@@ -16,7 +15,7 @@
 #
 # https://en.wikipedia.org/wiki/SRGB
 #
-# The colours were then adjusted to achieve equal luminance. However, that did
+# The colours were then adjusted to achieve equal luminance. However, that does
 # not actually yield colours with equal apparent brightness. This is due to the
 # "Helmholtz-Kohlrausch effect", which means that some saturated colours appear
 # brighter than others to the human eye. The theme is named after that.
@@ -33,8 +32,8 @@ Black=0,0,0
 Red=216,36,51
 Green=28,168,0
 Yellow=192,160,0
-Blue=0,72,216
-Magenta=180,60,204
+Blue=0,55,220
+Magenta=177,72,198
 Cyan=0,168,154
 White=191,191,191
 
@@ -43,6 +42,6 @@ BoldRed=255,102,102
 BoldGreen=0,244,0
 BoldYellow=240,240,0
 BoldBlue=85,170,255
-BoldMagenta=255,102,255
+BoldMagenta=255,114,255
 BoldCyan=0,240,240
 BoldWhite=255,255,255
diff --git a/themes/kohlrausch b/themes/kohlrausch
new file mode 100644
index 00000000..ddb7e0ce
--- /dev/null
+++ b/themes/kohlrausch
@@ -0,0 +1,49 @@
+# "kohlrausch" colour theme for mintty
+#
+# The aim of this theme is to provide vibrant colours where the normal and bold
+# levels each have approximately equal brightness. The variants of each colour
+# have slightly different hues to help distinguish them.
+#
+# Unlike in the "helmholtz" scheme, the normal blue has a similar brightness to
+# the other normal colours, which helps its readability but makes it less
+# suitable as a background colour.
+#
+# To level the colours, their luminance was calculated as follows:
+# - Gamma-expand the sRGB components by dividing each by 255 and applying the
+#   sRGB transfer function (which approximately means applying exponent 2.2).
+# - Combine the components with formula Y = 0.2126 R + 0.7152 G + 0.0722 B.
+# - Gamma-compress with the reverse transfer function (approximately: apply
+#   exponent 1/2.2).
+#
+# https://en.wikipedia.org/wiki/SRGB
+#
+# The colours were then adjusted to achieve equal luminance. However, that does
+# not actually yield colours with equal apparent brightness. This is due to the
+# "Helmholtz-Kohlrausch effect", which means that some saturated colours appear
+# brighter than others to the human eye. The theme is named after that.
+#
+# https://en.wikipedia.org/wiki/Helmholtz-Kohlrausch_effect
+#
+# There doesn't appear to be a generally valid model for compensating for the
+# effect, as it depends on observer, display device, and viewing environment.
+# Hence, correction factors were determined experimentally, ranging from 1.0
+# for yellow to 1.45 for red, and the colour components adjusted accordingly.
+# Of course, that is a highly subjective process ...
+
+Black=0,0,0
+Red=216,36,51
+Green=28,168,0
+Yellow=192,160,0
+Blue=0,102,255
+Magenta=177,72,198
+Cyan=0,168,154
+White=191,191,191
+
+BoldBlack=96,96,96
+BoldRed=255,102,102
+BoldGreen=0,244,0
+BoldYellow=240,240,0
+BoldBlue=85,170,255
+BoldMagenta=255,114,255
+BoldCyan=0,240,240
+BoldWhite=255,255,255
diff --git a/themes/luminous b/themes/luminous
index 9edd2413..f525f037 100644
--- a/themes/luminous
+++ b/themes/luminous
@@ -1,11 +1,8 @@
 # "luminous" colour theme for mintty
 #
 # The aim of this theme is to provide vibrant colours where the normal and bold
-# levels each have approximately equal luminance. The exception is normal blue,
-# which is somewhat darker than the others as a compromise between readability
-# on a black background and suitability as a background colour. The normal and
-# bold variant of each colour have slightly different hues to help distinguish
-# them.
+# levels each have approximately equal luminance. The variants of each colour
+# have slightly different hues to help distinguish them.
 #
 # To level the colours, their luminance was calculated as follows:
 # - Gamma-expand the sRGB components by dividing each by 255 and applying the
@@ -23,15 +20,16 @@
 #
 # https://en.wikipedia.org/wiki/Helmholtz-Kohlrausch_effect
 #
-# See the "helmholtz" theme for an attempt to compensate for that.
+# See also the "helmholtz" and "kohlrausch" themes that attempt to compensate
+# for that.
 
 Black=0,0,0
-Red=216,0,18
-Green=21,126,0
-Yellow=126,105,0
-Blue=0,72,216
-Magenta=180,0,216
-Cyan=0,120,110
+Red=228,0,19
+Green=22,132,0
+Yellow=135,112,0
+Blue=0,102,255
+Magenta=190,0,228
+Cyan=0,128,117
 White=191,191,191
 
 BoldBlack=96,96,96