SchemaDefinition.Create throws exception in Microsoft.ML.ImageAnalytics version 2.0

Question

The following line of code

SchemaDefinition def = SchemaDefinition.Create(typeof(ImageData), SchemaDefinition.Direction.Read);

throws

System.ArgumentOutOfRangeException: 'Could not determine an IDataView type and registered custom types for member Image (Parameter 'rawType')'

when using Microsoft.ML.ImageAnalytics version 2.0.

The same code works with no exceptions in Microsoft.ML.ImageAnalytics version 1.71

The ImageData class is defined as follows:

public class ImageData
{
    [ColumnName("image")]

    [ImageType(height:100, width:100)]
    public Bitmap Image { get; set; }
}

Is there anything that can be done in order to avoid this exception?

score 3 · Answer 1 · answered Jan 20 '23 at 13:05

As pointed in the question I did for the same issue, there is a breaking change in ML.NET 2.0 where, due to that System.Drawings is only supported by Windows, they have changed the class for image handling to MLImage (https://github.com/dotnet/machinelearning/blob/main/docs/release-notes/2.0/release-2.0.0.md#breaking-changes). So, they are suggesting to change the Bitmap class to their MLImage class.

1 Answers1