From e6239727a0f41ac988e5ada1ca3a88f33f21791e Mon Sep 17 00:00:00 2001
From: Dirk Lemstra <dirk@git.imagemagick.org>
Date: Mon, 28 Aug 2017 23:13:41 +0200
Subject: [PATCH] Added missing clear for the previousScanline when going to
 the next pass

---
 src/ImageSharp/Formats/Png/PngDecoderCore.cs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/ImageSharp/Formats/Png/PngDecoderCore.cs b/src/ImageSharp/Formats/Png/PngDecoderCore.cs
index 633d151b6..f58322ee5 100644
--- a/src/ImageSharp/Formats/Png/PngDecoderCore.cs
+++ b/src/ImageSharp/Formats/Png/PngDecoderCore.cs
@@ -515,7 +515,7 @@ namespace ImageSharp.Formats
                     this.currentRowBytesRead = 0;
 
                     Span<byte> scanSpan = this.scanline.Slice(0, bytesPerInterlaceScanline);
-                    Span<byte> prevSpan = this.previousScanline.Span.Slice(0, bytesPerInterlaceScanline);
+                    Span<byte> prevSpan = this.previousScanline.Slice(0, bytesPerInterlaceScanline);
                     var filterType = (FilterType)scanSpan[0];
 
                     switch (filterType)
@@ -556,6 +556,8 @@ namespace ImageSharp.Formats
                 }
 
                 this.pass++;
+                this.previousScanline.Clear();
+
                 if (this.pass < 7)
                 {
                     this.currentRow = Adam7FirstRow[this.pass];