asdfdocs

1 files changed, 14 insertions, 0 deletions

diff --git a/docs/deviation.txt b/docs/deviation.txt
index 42f38693..19046f08 100644
--- a/docs/deviation.txt
+++ b/docs/deviation.txt
@@ -43,3 +43,17 @@ we get
 A reasonable value for acceptable_error might be 2.5% or 3%. For a 1
 bit format 2.5% is a little less generous than the current 0.0064 (it
 is 0.0062), whereas 3% is a litt more generous (it is 0.0074)
+
+Another, perhaps better, possibility is to just reason as follows:
+
+By choosing a particular format, the user has indicated that they
+find an error of half a step in that format to be acceptable. We could
+simply say that pixman guarantees that the error is always less than
+say 52.5% of a pixel step.
+
+So a true value of 0.525 would be allowed to result in both 0 and
+1. But anything bigger than that would have to be 1.
+
+The more complicated scheme has the advantage that it doesn't refer to
+pixel steps and so the errors could be computed in some perceptually
+uniform color space such as CIELAB.