Fix sign error in dither.txt

1 files changed, 1 insertions, 4 deletions

diff --git a/docs/dither.txt b/docs/dither.txt
index 19b3f1c7..2c3eb132 100644
--- a/docs/dither.txt
+++ b/docs/dither.txt
@@ -76,7 +76,7 @@ Details:
  *       2 * x_a * x_b (U(b - a) + U(a - b) - 2 * rho)
  *
  * Since U is symmetric, we know that U(b - a) = U(a - b). Call this value u.
- * By setting d = x_a - x_b and f = F(a) - F(b), the above expression
+ * By setting d = x_a - x_b and f = F(b) - F(a), the above expression
  * now simplifies to:
  *
  *     Delta_E = 2 * (rho - u) * d^2 + 2 * f * d
@@ -102,9 +102,6 @@ Details:
  *       onto F at position a and b respectively.
  */
 
-
-
-
 Old algorithm:
 
 First generate white triangular sRGB noise. Then, convert to