From 1081b16a6c238434c7cec28aa925600a892a47bb Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Mon, 9 May 2016 09:08:38 +0530
Subject: [PATCH] ...

---
 src/calibre/utils/imageops/quantize.cpp | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/calibre/utils/imageops/quantize.cpp b/src/calibre/utils/imageops/quantize.cpp
index 664f7e5fd9..5a30fb389e 100644
--- a/src/calibre/utils/imageops/quantize.cpp
+++ b/src/calibre/utils/imageops/quantize.cpp
@@ -245,10 +245,8 @@ static void dither_image(const QImage &img, QImage &ans, QVector<QRgb> &color_ta
         line = reinterpret_cast<const QRgb*>(img.constScanLine(r));
         bits = ans.scanLine(r);
         is_odd = r & 1;
-        start = is_odd ? iwidth - 1 : 0;
-        delta = is_odd ? -1 : 1;
-        line1 = is_odd ? &err2 : &err1;
-        line2 = is_odd ? &err1 : &err2;
+        if (is_odd) { start = iwidth - 1; delta = -1; line1 = &err2; line2 = &err1; }
+        else { start = 0; delta = 1; line1 = &err1; line2 = &err2; }
         line2->fill(zero);
         for (c = start; 0 < (is_odd ? c + 1 : iwidth - c); c += delta) {
             pixel = *(line + c);