ImageEstimatorsCatalog.ResizeImages 方法

定义

命名空间:

Microsoft.ML

程序集:

Microsoft.ML.ImageAnalytics.dll

包:

Microsoft.ML.ImageAnalytics v2.0.0

创建一个 ImageResizingEstimator，它将图像的大小从 中指定的 inputColumnName 列调整为新列： outputColumnName。

public static Microsoft.ML.Transforms.Image.ImageResizingEstimator ResizeImages (this Microsoft.ML.TransformsCatalog catalog, string outputColumnName, int imageWidth, int imageHeight, string inputColumnName = default, Microsoft.ML.Transforms.Image.ImageResizingEstimator.ResizingKind resizing = Microsoft.ML.Transforms.Image.ImageResizingEstimator+ResizingKind.IsoCrop, Microsoft.ML.Transforms.Image.ImageResizingEstimator.Anchor cropAnchor = Microsoft.ML.Transforms.Image.ImageResizingEstimator+Anchor.Center);

static member ResizeImages : Microsoft.ML.TransformsCatalog * string * int * int * string * Microsoft.ML.Transforms.Image.ImageResizingEstimator.ResizingKind * Microsoft.ML.Transforms.Image.ImageResizingEstimator.Anchor -> Microsoft.ML.Transforms.Image.ImageResizingEstimator

<Extension()>
Public Function ResizeImages (catalog As TransformsCatalog, outputColumnName As String, imageWidth As Integer, imageHeight As Integer, Optional inputColumnName As String = Nothing, Optional resizing As ImageResizingEstimator.ResizingKind = Microsoft.ML.Transforms.Image.ImageResizingEstimator+ResizingKind.IsoCrop, Optional cropAnchor As ImageResizingEstimator.Anchor = Microsoft.ML.Transforms.Image.ImageResizingEstimator+Anchor.Center) As ImageResizingEstimator

参数

catalog

TransformsCatalog

转换的目录。

outputColumnName

String

转换 inputColumnName生成的列的名称。 此列的数据类型将与输入列的数据类型相同。

imageWidth

Int32

转换后的图像宽度。

imageHeight

Int32

转换后的图像高度。

inputColumnName

String

包含图像的列的名称。 此估算器通过 MLImage运行。

resizing

ImageResizingEstimator.ResizingKind

图像大小调整的类型，如 中指定的 ImageResizingEstimator.ResizingKind。

cropAnchor

ImageResizingEstimator.Anchor

放置定位点的位置，开始裁剪。 中定义的选项 ImageResizingEstimator.Anchor

返回

ImageResizingEstimator

示例

using System;
using System.IO;
using Microsoft.ML;
using Microsoft.ML.Data;

namespace Samples.Dynamic
{
    public static class ResizeImages
    {
        // Example on how to load the images from the file system, and resize them.
        public static void Example()
        {
            // Create a new ML context, for ML.NET operations. It can be used for
            // exception tracking and logging, as well as the source of randomness.
            var mlContext = new MLContext();

            // Downloading a few images, and an images.tsv file, which contains a
            // list of the files from the dotnet/machinelearning/test/data/images/.
            // If you inspect the fileSystem, after running this line, an "images"
            // folder will be created, containing 4 images, and a .tsv file
            // enumerating the images.
            var imagesDataFile = Microsoft.ML.SamplesUtils.DatasetUtils
                .GetSampleImages();

            // Preview of the content of the images.tsv file
            //
            // imagePath    imageType
            // tomato.bmp   tomato
            // banana.jpg   banana
            // hotdog.jpg   hotdog
            // tomato.jpg   tomato

            var data = mlContext.Data.CreateTextLoader(new TextLoader.Options()
            {
                Columns = new[]
                {
                        new TextLoader.Column("ImagePath", DataKind.String, 0),
                        new TextLoader.Column("Name", DataKind.String, 1),
                }
            }).Load(imagesDataFile);

            var imagesFolder = Path.GetDirectoryName(imagesDataFile);
            // Image loading pipeline.
            var pipeline = mlContext.Transforms.LoadImages("ImageObject",
                imagesFolder, "ImagePath")
                .Append(mlContext.Transforms.ResizeImages("ImageObjectResized",
                inputColumnName: "ImageObject", imageWidth: 100, imageHeight: 100));

            var transformedData = pipeline.Fit(data).Transform(data);
            // The transformedData IDataView contains the resized images now.

            // Preview the transformedData.
            PrintColumns(transformedData);

            // ImagePath    Name         ImageObject               ImageObjectResized
            // tomato.bmp   tomato       {Width=800, Height=534}   {Width=100, Height=100}
            // banana.jpg   banana       {Width=800, Height=288}   {Width=100, Height=100}
            // hotdog.jpg   hotdog       {Width=800, Height=391}   {Width=100, Height=100}
            // tomato.jpg   tomato       {Width=800, Height=534}   {Width=100, Height=100}
        }

        private static void PrintColumns(IDataView transformedData)
        {
            Console.WriteLine("{0, -25} {1, -25} {2, -25} {3, -25}", "ImagePath",
                "Name", "ImageObject", "ImageObjectResized");

            using (var cursor = transformedData.GetRowCursor(transformedData
                .Schema))
            {
                // Note that it is best to get the getters and values *before*
                // iteration, so as to facilitate buffer sharing (if applicable), and
                // column -type validation once, rather than many times.
                ReadOnlyMemory<char> imagePath = default;
                ReadOnlyMemory<char> name = default;
                MLImage imageObject = null;
                MLImage resizedImageObject = null;

                var imagePathGetter = cursor.GetGetter<ReadOnlyMemory<char>>(cursor
                    .Schema["ImagePath"]);

                var nameGetter = cursor.GetGetter<ReadOnlyMemory<char>>(cursor
                    .Schema["Name"]);

                var imageObjectGetter = cursor.GetGetter<MLImage>(cursor.Schema[
                    "ImageObject"]);

                var resizedImageGetter = cursor.GetGetter<MLImage>(cursor.Schema[
                    "ImageObjectResized"]);

                while (cursor.MoveNext())
                {
                    imagePathGetter(ref imagePath);
                    nameGetter(ref name);
                    imageObjectGetter(ref imageObject);
                    resizedImageGetter(ref resizedImageObject);

                    Console.WriteLine("{0, -25} {1, -25} {2, -25} {3, -25}",
                        imagePath, name,
                        $"Width={imageObject.Width}, Height={imageObject.Height}",
                        $"Width={resizedImageObject.Width}, Height={resizedImageObject.Height}");
                }

                // Dispose the image.
                imageObject.Dispose();
                resizedImageObject.Dispose();
            }
        }
    }
}