From a239e60885030c15d3fffa505415657c159f5b4d Mon Sep 17 00:00:00 2001 From: Simanto Rahman Date: Tue, 30 Oct 2018 13:52:02 -0230 Subject: [PATCH] Algorithm behaves abnormally when applied with ParallelHelpers --- .../AdaptiveThresholdProcessor.cs | 118 +++++++++--------- 1 file changed, 57 insertions(+), 61 deletions(-) diff --git a/src/ImageSharp/Processing/Processors/Binarization/AdaptiveThresholdProcessor.cs b/src/ImageSharp/Processing/Processors/Binarization/AdaptiveThresholdProcessor.cs index 21c7f4f57c..030768e69b 100644 --- a/src/ImageSharp/Processing/Processors/Binarization/AdaptiveThresholdProcessor.cs +++ b/src/ImageSharp/Processing/Processors/Binarization/AdaptiveThresholdProcessor.cs @@ -76,7 +76,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Binarization /// protected override void OnFrameApply(ImageFrame source, Rectangle sourceRectangle, Configuration configuration) { - var intersect = Rectangle.Intersect(sourceRectangle, source.Bounds()); + Rectangle intersect = Rectangle.Intersect(sourceRectangle, source.Bounds()); + + // Used ushort because the values should never exceed max ushort value ushort startY = (ushort)intersect.Y; ushort endY = (ushort)intersect.Bottom; ushort startX = (ushort)intersect.X; @@ -85,79 +87,73 @@ namespace SixLabors.ImageSharp.Processing.Processors.Binarization ushort width = (ushort)intersect.Width; ushort height = (ushort)intersect.Height; - // Tweaked to support upto 4k wide pixels and not more. 4096 / 16 is 256 thus the '-1' - byte clusterSize = (byte)((width / 16) - 1); + // ClusterSize defines the size of cluster to used to check for average. Tweaked to support upto 4k wide pixels and not more. 4096 / 16 is 256 thus the '-1' + byte clusterSize = (byte)Math.Truncate((width / 16f) - 1); - // Using pooled 2d buffer for integer image table + // Using pooled 2d buffer for integer image table and temp memory to hold Rgb24 converted pixel data using (Buffer2D intImage = configuration.MemoryAllocator.Allocate2D(width, height)) - using (IMemoryOwner tmpBuffer = configuration.MemoryAllocator.Allocate(width * height)) + using (IMemoryOwner bulkRgbBuf = configuration.MemoryAllocator.Allocate(width * height)) { + // Defines the rectangle section of the image to work on Rectangle workingRectangle = Rectangle.FromLTRB(startX, startY, endX, endY); - this.pixelOpInstance.ToRgb24(source.GetPixelSpan(), tmpBuffer.GetSpan()); + // TPixel span of the original image + Span pixelSpan = source.GetPixelSpan(); + + // RGB24 span of the converted pixel buffer + Span rgbSpan = bulkRgbBuf.GetSpan(); - ParallelHelper.IterateRows( - workingRectangle, - configuration, - rows => + // Bulk conversion to RGB24 + this.pixelOpInstance.ToRgb24(pixelSpan, rgbSpan); + + for (int x = startX; x < endX; x++) + { + ulong sum = 0; + for (int y = startY; y < endY; y++) { - Span rgbSpan = tmpBuffer.GetSpan(); - uint sum; - for (int x = startX; x < endX; x++) + ref Rgb24 rgb = ref rgbSpan[(width * y) + x]; + + sum += (ulong)(rgb.R + rgb.G + rgb.B); + + if (x != 0) + { + intImage[x - startX, y - startY] = intImage[x - startX - 1, y - startY] + sum; + } + else { - sum = 0; - for (int y = rows.Min; y < rows.Max; y++) - { - ref Rgb24 rgb = ref rgbSpan[(width * y) + x]; - sum += (uint)(rgb.R + rgb.G + rgb.B); - - if (x > 0) - { - intImage[x - startX, y - startY] = intImage[x - 1 - startX, y - startY] + sum; - } - else - { - intImage[x - startX, y - startY] = sum; - } - } + intImage[x - startX, y - startY] = sum; } - }); + } + } - ParallelHelper.IterateRows( - workingRectangle, - configuration, - rows => + ushort x1, x2, y1, y2; + uint count = 0; + + for (int x = startX; x < endX; x++) + { + long sum = 0; + for (int y = startY; y < endY; y++) { - ushort x1, x2, y1, y2; - Span rgbSpan = tmpBuffer.GetSpan(); - long sum = 0; - uint count = 0; + ref Rgb24 rgb = ref rgbSpan[(width * y) + x]; + + x1 = (ushort)Math.Max(x - startX - clusterSize + 1, 0); + x2 = (ushort)Math.Min(x - startX + clusterSize + 1, width - 1); + y1 = (ushort)Math.Max(y - startY - clusterSize + 1, 0); + y2 = (ushort)Math.Min(y - startY + clusterSize + 1, height - 1); + + count = (uint)((x2 - x1) * (y2 - y1)); + sum = (long)(intImage[x2, y2] - intImage[x1, y2] - intImage[x2, y1] + intImage[x1, y1]); - for (int x = startX; x < endX; x++) + if ((rgb.R + rgb.G + rgb.B) * count <= sum * this.ThresholdLimit) { - for (int y = rows.Min; y < rows.Max; y++) - { - ref Rgb24 rgb = ref rgbSpan[(width * y) + x]; - x1 = (ushort)Math.Max(x - clusterSize + 1 - startX, 0); - x2 = (ushort)Math.Min(x + clusterSize + 1 - startX, endX - startX - 1); - y1 = (ushort)Math.Max(y - clusterSize + 1 - startY, 0); - y2 = (ushort)Math.Min(y + clusterSize + 1 - startY, endY - startY - 1); - - count = (uint)((x2 - x1) * (y2 - y1)); - - sum = (long)(intImage[x2, y2] - intImage[x2, y1] - intImage[x1, y2] + intImage[x1, y1]); - - if ((rgb.R + rgb.G + rgb.B) * count <= sum * this.ThresholdLimit) - { - source[x, y] = this.Lower; - } - else - { - source[x, y] = this.Upper; - } - } - } - }); + pixelSpan[(width * y) + x] = this.Lower; + } + else + { + pixelSpan[(width * y) + x] = this.Upper; + } + } + } } } }