extend doc about contrast and brightness

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/info/blueshift.texinfo b/info/blueshift.texinfo
index c5c84f1..877410d 100644
--- a/info/blueshift.texinfo
+++ b/info/blueshift.texinfo
@@ -281,6 +281,10 @@ Adjusts the contrast to @code{rgb}. This
 function assumes the black is 0, and white
 is 1, so you should apply this before brightness.
 
+Note: This does not correspond to the contrast
+on monitors control panels used to calibrate
+the white point.
+
 @item rgb_contrast(r, g, b)
 Adjusts the contrast to @code{r}, @code{g}
 and @code{b} on the red, green and blue curves,
@@ -288,6 +292,10 @@ respectively. This function assumes the black is
 0, and white is 1, so you should apply this
 before brightness.
 
+Note: This does not correspond to the contrast
+on monitors control panels used to calibrate
+the white point.
+
 @item cie_contrast(y)
 Adjusts the contrast to @code{y}.
 The function calculate the values by using
@@ -296,20 +304,45 @@ colour space. This function assumes the black
 is 0, and white is 1, so you should apply
 this before brightness.
 
+Note: This does not correspond to the contrast
+on monitors control panels used to calibrate
+the white point.
+
 @item rgb_brightness(rgb)
 Adjusts the brightness to @code{rgb}.
+Note: This does not correspond to the contrast
+on monitors control panels used to calibrate
+the white point.
+
+Note: This does not correspond to the brightness
+on monitors control panels used to calibrate
+the black point point, rather it corresponds
+to the contrast on monitors control panels
+used to calibrate white point.
 
 @item rgb_brightness(r, g, b)
 Adjusts the brightness to @code{r}, @code{g}
 and @code{b} on the red, green and blue curves,
 respectively.
 
+Note: This does not correspond to the brightness
+on monitors control panels used to calibrate
+the black point point, rather it corresponds
+to the contrast on monitors control panels
+used to calibrate white point.
+
 @item cie_brightness(y)
 Adjusts the brightness to @code{y}.
 The function calculate the values by using
 the CIE xyY colour space instead of the sRGB
 colour space.
 
+Note: This does not correspond to the brightness
+on monitors control panels used to calibrate
+the black point point, rather it corresponds
+to the contrast on monitors control panels
+used to calibrate white point.
+
 @item linearise()
 Converts the colour curves from sRGB to
 linear RGB. sRGB is the default colour space.
@@ -374,6 +407,12 @@ respectively.
 Changes the black point to @code{rgb_min}, and
 the white point to @code{rgb_max}.
 
+@code{rgb_min} corresponds to the brightness
+on monitor control panels used to calibrate the
+black point. @code{rgb_max} corresponds to the
+contrast on monitor control panels used to
+calibrate the white point.
+
 @item rgb_limits(r_min, r_max, g_min, g_max, b_min, b_max)
 Changes the black point to (@code{r_min},
 @code{g_min}, @code{b_min}), and the white