diff -urp yagf-0.9.5/src/core/qipgrayscaleimage.cpp yagf-0.9.5-nothreads/src/core/qipgrayscaleimage.cpp
--- yagf-0.9.5/src/core/qipgrayscaleimage.cpp	2015-02-17 07:50:24.000000000 +0600
+++ yagf-0.9.5-nothreads/src/core/qipgrayscaleimage.cpp	2017-03-22 10:47:47.082433808 +0700
@@ -335,7 +335,8 @@ QIPGrayscaleImage QIPGrayscaleImage::cop
     r1.x1 = x1;
     r1.x2 = x2;
     r1.y1 = y1;
-    r1.y2 = (y2 - y1)/2;
+//    r1.y2 = (y2 - y1)/2;
+    r1.y2 = y2;
     IntRect r2;
     r2.x1 = x1;
     r2.x2 = x2;
@@ -354,9 +355,9 @@ QIPGrayscaleImage QIPGrayscaleImage::cop
 #endif
 #ifdef IPRIT_MULTITHREADING
     QFuture<void> future1 = QtConcurrent::run(this, &QIPGrayscaleImage::copyInternal2, r1, s, d);
-    QFuture<void> future2 = QtConcurrent::run(this, &QIPGrayscaleImage::copyInternal2, r2, s, d);
+//    QFuture<void> future2 = QtConcurrent::run(this, &QIPGrayscaleImage::copyInternal2, r2, s, d);
     future1.waitForFinished();
-    future2.waitForFinished();
+//    future2.waitForFinished();
 #endif
 
     return result;