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PredictionPool will not let me have an MLImage member of an input or output type #6936
Description
System Information (please complete the following information):
- Windows 10
- ML.NET 3.0.0
- .NET 7.0
Describe the bug
There are a number of examples that use a PredictionEngine with an input type or output type that has a member of MLImage type, for example #6886
However, my code is breaking when I call
var prePredictionEngine = mlContext.Model.CreatePredictionEngine<InputType, OutputType>(model);
public class InputType
{
public string Label;
[ColumnName("Image")]
[ImageType(224, 224)]
public MLImage Image { get; set; }
}
This is the error that comes up
Here's the console output
EXCEPTION
#########
System.NotImplementedException: Type 'Microsoft.ML.Data.MLImage' is not yet supported.
at Microsoft.ML.Data.TypedCursorable`1.TypedRowBase.GenerateSetter(DataViewRow input, Int32 index, Column column, Delegate poke, Delegate peek)
at Microsoft.ML.Data.TypedCursorable`1.TypedRowBase..ctor(TypedCursorable`1 parent, DataViewRow input, String channelMessage)
at Microsoft.ML.Data.TypedCursorable`1.TypedRow..ctor(TypedCursorable`1 parent, DataViewRow input)
at Microsoft.ML.Data.TypedCursorable`1.GetRow(DataViewRow input)
at Microsoft.ML.PredictionEngineBase`2.PredictionEngineCore(IHostEnvironment env, InputRow`1 inputRow, IRowToRowMapper mapper, Boolean ignoreMissingColumns, SchemaDefinition outputSchemaDefinition, Action& disposer, IRowReadableAs`1& outputRow)
at Microsoft.ML.PredictionEngineBase`2..ctor(IHostEnvironment env, ITransformer transformer, Boolean ignoreMissingColumns, SchemaDefinition inputSchemaDefinition, SchemaDefinition outputSchemaDefinition, Boolean ownsTransformer)
at Microsoft.ML.PredictionEngine`2..ctor(IHostEnvironment env, ITransformer transformer, Boolean ignoreMissingColumns, SchemaDefinition inputSchemaDefinition, SchemaDefinition outputSchemaDefinition, Boolean ownsTransformer)
at Microsoft.ML.PredictionEngineExtensions.CreatePredictionEngine[TSrc,TDst](ITransformer transformer, IHostEnvironment env, Boolean ignoreMissingColumns, SchemaDefinition inputSchemaDefinition, SchemaDefinition outputSchemaDefinition, Boolean ownsTransformer)
at Microsoft.ML.ModelOperationsCatalog.CreatePredictionEngine[TSrc,TDst](ITransformer transformer, Boolean ignoreMissingColumns, SchemaDefinition inputSchemaDefinition, SchemaDefinition outputSchemaDefinition)
at ImageClassification.ModelScorer.TFModelScorer.PredictDataUsingModelFromStructuredDirectory(IDataView testDataView) in C:\MLsamples\machinelearning-samples\samples\csharp\getting-started\DeepLearning_ImageClassification_TensorFlow\ImageClassification\ModelScorer\TFModelScorer.cs:line 181
at ImageClassification.ModelScorer.TFModelScorer.ScoreUsingStructuredDirectory() in C:\MLsamples\machinelearning-samples\samples\csharp\getting-started\DeepLearning_ImageClassification_TensorFlow\ImageClassification\ModelScorer\TFModelScorer.cs:line 67
at ImageClassification.Program.Main(String[] args) in C:\MLsamples\machinelearning-samples\samples\csharp\getting-started\DeepLearning_ImageClassification_TensorFlow\ImageClassification\Program.cs:line 32
I can make things work straight up by wrapping the data in a IDataView and calling .Transform(), but that defeats the point of having a PredictionEngine
Activity
tearlant commentedon Jan 3, 2024
Update: I was able to create a workaround, by breaking things into two back to back PredictionEngines, the first of which is a pipeline with some data manipulation, then the first engine is just a
ResizeImagesand anExtractImagestransform, whose type is a VectorType instead of an ImageType.But this feels like unnecessary gymnastics. I'm not sure what I'm doing wrong.
rosebyte commentedon Oct 23, 2026
Triage: it feels a bug, we will investigate by priority.