Add onnx support for VisionEncoderDecoder
# What does this PR do?

Fixes #14812 
This PR enables the export of VisionEncoderDecoder models to ONNX.

The VisionEncoderDecoder models contains two parts, a vision transformer encoder and language modelling decoder. Both the models are exported to onnx separately as `encoder_model.onnx` and `decoder_model.onnx`.

To enable the export of the model, the export call in the __main__ file is segregated based on the model_kind.

Usage
```python
model_ckpt = "nlpconnect/vit-gpt2-image-captioning"
!python -m transformers.onnx --model={model_ckpt} --feature=vision2seq-lm onnx/ --atol 1e-3
```
_The documentation is not available anymore as the PR was closed or merged._<|||||>Hi, I would like to help here, It would be good for using Donut easier with ONNX :) @mht-sharma I can help fixing the errors that @lewtun comments<|||||>> Hi, I would like to help here, It would be good for using Donut easier with ONNX :) @mht-sharma I can help fixing the errors that @lewtun comments

Hi @WaterKnight1998 thanks for the help.  I have updated with the PR with a new commit addressing the comments.<|||||>> Thanks for adding ONNX support for this highly request model type @mht-sharma 🔥 !!
> 
> Overall the PR looks great and there's a few small things we need to correct:
> 
> * since this model type is kind of special, I think we should document somewhere in the `serialization.mdx` docs that these models produce _two_ files
> * you need to update the table in `serialization.mdx` by running `make fix-copies`

* Added a Tip for the generation of 2 onnx files or VisionEncoderDecoder models.
*  Updated serialization.mdx with `make fix-copies`<|||||>> Thanks for iterating on this @mht-sharma - it's looking very good!
> 
> I've left a bunch of nits, but once they're addressed I think this should be good to merge. Would you mind confirming that all the slow tests pass with these changes?
> 
> ```
> RUN_SLOW=1 pytest tests/onnx/test_onnx_v2.py
> ```

All tests pass<|||||>@mht-sharma For the command

```
python -m transformers.onnx --model=naver-clova-ix/donut-base-finetuned-cord-v2 --feature=vision2seq-lm scratch/onnx
```

It's throwing output value error

```
Validating ONNX model...
	-[✓] ONNX model output names match reference model ({'last_hidden_state'})
	- Validating ONNX Model output "last_hidden_state":
		-[✓] (3, 1200, 1024) matches (3, 1200, 1024)
		-[x] values not close enough (atol: 1e-05)
Traceback (most recent call last):
  File "/usr/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/local/lib/python3.7/dist-packages/transformers/onnx/__main__.py", line 180, in <module>
    main()
  File "/usr/local/lib/python3.7/dist-packages/transformers/onnx/__main__.py", line 113, in main
    args.atol if args.atol else encoder_onnx_config.atol_for_validation,
  File "/usr/local/lib/python3.7/dist-packages/transformers/onnx/convert.py", line 456, in validate_model_outputs
    "Outputs values doesn't match between reference model and ONNX exported model: "
ValueError: Outputs values doesn't match between reference model and ONNX exported model: Got max absolute difference of: 0.0018157958984375 for [  1.5980988   0.5988426 -14.8206215 ...  -5.1114273   4.5024166
   2.8833218] vs [  1.5982218    0.59886694 -14.820812   ...  -5.1115417    4.502474
   2.883381  ]
```

Am I missing something? or any suggestions? Thank you.<|||||>> @mht-sharma For the command
> 
> ```
> python -m transformers.onnx --model=naver-clova-ix/donut-base-finetuned-cord-v2 --feature=vision2seq-lm scratch/onnx
> ```
> 
> It's throwing output value error
> 
> ```
> Validating ONNX model...
> 	-[✓] ONNX model output names match reference model ({'last_hidden_state'})
> 	- Validating ONNX Model output "last_hidden_state":
> 		-[✓] (3, 1200, 1024) matches (3, 1200, 1024)
> 		-[x] values not close enough (atol: 1e-05)
> Traceback (most recent call last):
>   File "/usr/lib/python3.7/runpy.py", line 193, in _run_module_as_main
>     "__main__", mod_spec)
>   File "/usr/lib/python3.7/runpy.py", line 85, in _run_code
>     exec(code, run_globals)
>   File "/usr/local/lib/python3.7/dist-packages/transformers/onnx/__main__.py", line 180, in <module>
>     main()
>   File "/usr/local/lib/python3.7/dist-packages/transformers/onnx/__main__.py", line 113, in main
>     args.atol if args.atol else encoder_onnx_config.atol_for_validation,
>   File "/usr/local/lib/python3.7/dist-packages/transformers/onnx/convert.py", line 456, in validate_model_outputs
>     "Outputs values doesn't match between reference model and ONNX exported model: "
> ValueError: Outputs values doesn't match between reference model and ONNX exported model: Got max absolute difference of: 0.0018157958984375 for [  1.5980988   0.5988426 -14.8206215 ...  -5.1114273   4.5024166
>    2.8833218] vs [  1.5982218    0.59886694 -14.820812   ...  -5.1115417    4.502474
>    2.883381  ]
> ```
> 
> Am I missing something? or any suggestions? Thank you.

Hi @BakingBrains , you need to increase the atol for the model.  Please pass `--atol <value>` in the above command to export the model.<|||||>Also @mht-sharma is there any reference for the usage of ```ORTModelForConditionalGeneration``` (for encoder-decoder models) for inferencing.

Thanks and Regards<|||||>> Also @mht-sharma is there any reference for the usage of `ORTModelForConditionalGeneration` (for encoder-decoder models) for inferencing.
> 
> Thanks and Regards

Hi @BakingBrains, currently only text seq2seq encoder-decoder models are supported in optimum. Please find the reference here: [ORTModelForSeq2SeqLM](https://huggingface.co/docs/optimum/onnxruntime/package_reference/modeling_ort#optimum.onnxruntime.ORTModelForSeq2SeqLM)

I will be adding support for other modalities in optimum soon. Stay tuned!

<|||||>@NielsRogge  @mht-sharma  I referred to some of issues in Model Conversion , I have transformed my Tr-OCR base printed model into Two File encoder.onnx and decoder.onnx. Now as per this (https://github.com/huggingface/transformers/issues/19811) which i have followed thoroughly,I was trying with ORTEncoder and ORTDecoder but there seems to be issues in model.generate and also gives backhooks issue.Can you help here?<|||||>Hi @umanniyaz , could you share what is the error message you are getting? Probably would be best to open a new issue or comment on existing issue with sample snippet and error message. 

I will be adding the support for the above model in `optimum` onnxruntime soon, which would enable you to run inference with the model directly. I could update the PR here in some days to keep you in loop. <|||||>Hi @mht-sharma,  I'm getting this error message
```
!python -m transformers.onnx --model="microsoft/trocr-large-printed" --feature=vision2seq-lm onnx/ --atol 1e-3

Framework not requested. Using torch to export to ONNX.
Some weights of VisionEncoderDecoderModel were not initialized from the model checkpoint at microsoft/trocr-large-printed and are newly initialized: ['encoder.pooler.dense.bias', 'encoder.pooler.dense.weight']
You should probably TRAIN this model on a down-stream task to be able to use it for predictions and inference.
Using framework PyTorch: 1.13.0+cu116
/usr/local/lib/python3.8/dist-packages/transformers/models/vit/modeling_vit.py:176: TracerWarning: Converting a tensor to a Python boolean might cause the trace to be incorrect. We can't record the data flow of Python values, so this value will be treated as a constant in the future. This means that the trace might not generalize to other inputs!
  if num_channels != self.num_channels:
/usr/local/lib/python3.8/dist-packages/transformers/models/vit/modeling_vit.py:181: TracerWarning: Converting a tensor to a Python boolean might cause the trace to be incorrect. We can't record the data flow of Python values, so this value will be treated as a constant in the future. This means that the trace might not generalize to other inputs!
  if height != self.image_size[0] or width != self.image_size[1]:
tcmalloc: large alloc 1219141632 bytes == 0x12f19c000 @  0x7fb5e825d887 0x7fb5e6b53c29 0x7fb5e6b54afb 0x7fb5e6b54bb4 0x7fb5e6b54f9c 0x7fb520720a74 0x7fb520720fa5 0x7fb50ff9bced 0x7fb5355c16b4 0x7fb53507e6af 0x5d80be 0x5d8d8c 0x4fedd4 0x4997c7 0x55cd91 0x5d8941 0x49abe4 0x55cd91 0x5d8941 0x49abe4 0x55d078 0x5d8941 0x49abe4 0x55cd91 0x5d8941 0x4990ca 0x5d8868 0x4990ca 0x55cd91 0x55d743 0x627376
tcmalloc: large alloc 1219141632 bytes == 0x177c46000 @  0x7fb5e825b1e7 0x4d30a0 0x5dede2 0x7fb5355c16eb 0x7fb53507e6af 0x5d80be 0x5d8d8c 0x4fedd4 0x4997c7 0x55cd91 0x5d8941 0x49abe4 0x55cd91 0x5d8941 0x49abe4 0x55d078 0x5d8941 0x49abe4 0x55cd91 0x5d8941 0x4990ca 0x5d8868 0x4990ca 0x55cd91 0x55d743 0x627376 0x5aaeb9 0x4990ca 0x55cd91 0x5d8941 0x4990ca
Validating ONNX model...
	-[✓] ONNX model output names match reference model ({'last_hidden_state'})
	- Validating ONNX Model output "last_hidden_state":
		-[✓] (3, 577, 1024) matches (3, 577, 1024)
		-[x] values not close enough (atol: 0.001)
Traceback (most recent call last):
  File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/usr/local/lib/python3.8/dist-packages/transformers/onnx/__main__.py", line 180, in <module>
    main()
  File "/usr/local/lib/python3.8/dist-packages/transformers/onnx/__main__.py", line 107, in main
    validate_model_outputs(
  File "/usr/local/lib/python3.8/dist-packages/transformers/onnx/convert.py", line 472, in validate_model_outputs
    raise ValueError(
ValueError: Outputs values doesn't match between reference model and ONNX exported model: Got max absolute difference of: 0.002560138702392578 for [ -6.9223547   -1.2663026   -6.01969     -4.5837965    6.1642013
   2.0628624   -3.5507686    1.9246662   -0.676687    -1.4317726
  -2.3281486   -1.0843381   -8.45131     -5.4161043    6.8614235
   4.190215    -5.2153773    3.0814483    0.63340956  -2.0609605
  -8.46502      0.8696586   -6.97839      2.6996267    2.5350282
  -8.500374    -4.0548806    1.1920781   -3.4029136   -5.475586
   0.7265783    1.5491551  -11.724315   -10.578344     0.1786897
  -0.5544502   -0.03817908  -1.506731    -6.7059665    2.4884484
 -10.02477      3.6103365    4.648042  ] vs [ -6.921267    -1.2674816   -6.02225     -4.585174     6.1653543
   2.0647495   -3.551866     1.9266967   -0.67827606  -1.4307456
  -2.3269713   -1.0858293   -8.453766    -5.4173226    6.862612
   4.1921353   -5.216509     3.0834184    0.6319726   -2.0598402
  -8.4638815    0.8707002   -6.9765515    2.6985872    2.533873
  -8.501539    -4.0534215    1.1903901   -3.401852    -5.477874
   0.72761816   1.5506129  -11.725906   -10.577168     0.1799282
  -0.55576885  -0.0398552   -1.5055205   -6.7073493    2.489525
 -10.022912     3.6091       4.646897  ]
```

https://colab.research.google.com/drive/1CxngHndMjLmpRkDreOS2GJSHbtcH1Olr#scrollTo=fc5SIz6uzs6p

in colab when switching to gpu the result it similar.

<|||||>@matthewchung74 it works with ```--atol 1e-2```
```!python -m transformers.onnx --model="microsoft/trocr-large-printed" --feature=vision2seq-lm onnx/ --atol 1e-2```

![image](https://user-images.githubusercontent.com/51019420/210029360-355ced8a-23ec-42ba-a266-687b3cc91bb6.png)
<|||||>@BakingBrains thank you very much. do you see any improvement in performance with the onnx? I don't for both gpu and cpu. I'm not sure I really understand. if you have any general thoughts, it'd be appreciated. I have sample code below.
 https://colab.research.google.com/drive/1CxngHndMjLmpRkDreOS2GJSHbtcH1Olr#scrollTo=I0xqkudSoxZw<|||||>@matthewchung74 There won't be that much difference you can see in terms of OCR performance. But there will be difference in inference speed as well as the consumption of resources.<|||||>odd, I must be doing something wrong, since my inference using onnx is 75% slower. thanks for the response. I'll have to work on it some more.<|||||>Inference of ONNX on GPU or CPU? because in one of my case the ONNX pipeline on GPU was taking 4.7 sec and same on CPU it was 6.2 sec

Regarding the original model the inference speed on CPU for the pipeline was 7.4 sec whereas for the ONNX was 4.1 sec<|||||>After getting ONNX -encoder.onnx and decoder.onnx , on running in Seq2seq ONNX, model inference improves but Accuracy of OCR gets worse<|||||>use this for inference @matthewchung74  @BakingBrains  https://github.com/huggingface/transformers/issues/20644<|||||>@umanniyaz I tried a script which is pretty much the same as @mht-sharma has here. https://gist.github.com/mht-sharma/f38c670930ac7df413c07327e692ee39. the inference script in #20644 also looks pretty much the same as ant-sharmas. I'm not really sure what I am missing. do you have your experiment with the better performance in a colab or something sharable?<|||||>Hi @matthewchung74 , I am working on the inference of such models on [optimum@588](https://github.com/huggingface/optimum/pull/588). This implementation would use the iobinding to make the inference faster on GPU.

As per the thread above, the model was exported using an `--atol` of 1e-2, which is quite high and may result in accuracy drop on inference. Would separately check this once the above implementation is completed.<|||||>Updated!
Hi @matthewchung74 , probably try this :
https://github.com/umanniyaz/TR-OCR-ONNX-Optimization

From this original script  https://gist.github.com/mht-sharma/f38c670930ac7df413c07327e692ee39 as shared by @mht-sharma 

It gives good inference and models accuracy remains preserved.

Try to keep model initialisations at compile time <|||||>@umanniyaz thank you for sharing .  I'm still seeing some performance issues. I'm running your code almost as is and getting the following as output.

```
Model Output Original is :  TICKET
Original time:  1.5399658679962158 TICKET
Model Ouput ORT is :  TICKET
ORT time:  3.5313572883605957 TICKET
```
here is the code. perhaps the difference is the test image. is your test image something you can share?
https://colab.research.google.com/drive/1ojsslQPxUO67_dGzI4ok4rRk6CSlcwf4?usp=sharing<|||||>hello, someone gives me an onnx model for TrOcr  please
<|||||>> hello, someone gives me an onnx model for TrOcr please

Hi @Kamilya2020 pls use the following guide to export the model to onnx. https://huggingface.co/docs/optimum/exporters/onnx/usage_guides/export_a_model <|||||>Hi @mht-sharma ,
can u help me please
I have this code

`using Microsoft.AspNetCore.Mvc;
using Microsoft.ML;
using Microsoft.ML.Data;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;
using SixLabors.ImageSharp.PixelFormats;

namespace OcrSolution.API.Controllers;

    public class ModelInput
    {
        [ColumnName("input1")]
        [VectorType(1,1, 64, 64)]
        public float[,,,] Input { get; set; }
    }

    public class ModelOutput
    {
        [ColumnName("output")]
        [VectorType(1,1, 97)]
        public float[,,] Output { get; set; }
    }

    public class OcrController : ControllerBase
    {
        private readonly MLContext _mlContext;
        private PredictionEngine<ModelInput, ModelOutput> _predictionEngine;

        public OcrController()
        {
            _mlContext = new MLContext();

            try
            {
                // Load the ONNX model
                var modelPath =
                    "C:\\Users\\k.mimouni\\Desktop\\ocr web app\\sw-kamilia-2023\\components\\Server\\OcrSolution.API\\assets\\Model\\1_recognition_model.onnx";
                var pipeline = _mlContext.Transforms.ApplyOnnxModel(modelPath);
                var dataView = _mlContext.Data.LoadFromEnumerable(new[] { new ModelInput() });
                var transformer = pipeline.Fit(dataView);

                // Verify transformer is not null after fitting
                if (transformer == null)
                {
                    throw new Exception("Transformer is null after fitting the pipeline.");
                }

                _predictionEngine = _mlContext.Model.CreatePredictionEngine<ModelInput, ModelOutput>(transformer);

                // Verify predictionEngine is not null after creation
                if (_predictionEngine == null)
                {
                    throw new Exception("Prediction engine is null after creation.");
                }

                Console.WriteLine("ONNX model loaded successfully.");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error loading ONNX model: {ex.Message}");
                _predictionEngine = null; // Set _predictionEngine to null in case of an error
            }
        }

       [HttpPost("ocr")]
public IActionResult PerformOCR(IFormFile imageFile)
{
    if (_predictionEngine != null)
    {
        try
        {
            // Check if a file is uploaded
            if (imageFile != null && imageFile.Length > 0)
            {
                // Resize and load the image data
                var image = ResizeImage(imageFile);
                if (image == null)
                {
                    Console.WriteLine("Failed to resize the image.");
                    return StatusCode(500, "Failed to resize the image.");
                }

                var imageData = LoadImageData(image);

                // Create the model input
                var input = new ModelInput { Input = imageData };

                if (input == null)
                {
                    Console.WriteLine("Failed to create the model input.");
                    return StatusCode(500, "Failed to create the model input.");
                }

                // Make a prediction
                var prediction = _predictionEngine.Predict(input);

                if (prediction == null || prediction.Output == null)
                {
                    Console.WriteLine("Failed to make a prediction or prediction output is null.");
                    return StatusCode(500, "Failed to make a prediction or prediction output is null.");
                }

                // Process the output and extract the text
                var extractedText = ExtractText(prediction.Output);

                // Return the extracted text
                return Ok(new { text = extractedText });
            }

            // No image file uploaded
            Console.WriteLine("No image file uploaded.");
            return BadRequest("No image file uploaded.");
        }
        catch (Exception ex)
        {
            // Error occurred while performing OCR
            Console.WriteLine($"An error occurred while performing OCR: {ex}");
            return StatusCode(500, $"An error occurred while performing OCR: {ex}");
        }
    }

    // Error loading ONNX model or prediction engine
    return StatusCode(500, "Error loading ONNX model or prediction engine.");
}


        private Image<Rgba32> ResizeImage(IFormFile imageFile)
        {
            using (var memoryStream = new MemoryStream())
            {
                // Copy the file content to a memory stream
                imageFile.CopyTo(memoryStream);

                // Load the image using SixLabors.ImageSharp
                memoryStream.Seek(0, SeekOrigin.Begin);
                var image = Image.Load<Rgba32>(memoryStream, out var format);

                if (image == null)
                {
                    throw new Exception("Failed to load the image.");
                }

                // Resize the image
                var resizedImage = image.Clone(x => x.Resize(new ResizeOptions
                {
                    Size = new Size(754, 64),
                    Mode = ResizeMode.Stretch
                }));

                if (resizedImage == null)
                {
                    throw new Exception("Failed to resize the image.");
                }

                return resizedImage;
            }
        }

        private float[,,,] LoadImageData(Image<Rgba32> image)
        {
            var imageData = new float[1, 1, image.Height, image.Width];

            // Iterate over the pixels and convert them to float values
            for (int y = 0; y < image.Height; y++)
            {
                for (int x = 0; x < image.Width; x++)
                {
                    var pixel = image[x, y];
                    var pixelValue = GetPixelValue(pixel);
                    imageData[0, 0, y, x] = pixelValue;
                }
            }

            return imageData;
        }


        private float GetPixelValue(Rgba32 pixel)
        {
            // Normalize the pixel value to the range [0, 1]
            return pixel.R / 255f;
        }

        private string ExtractText(float[,,] output)
        {
            string extractedText = "";
            for (int b = 0; b < output.GetLength(0); b++) // batch size
            {
                for (int h = 0; h < output.GetLength(1); h++) // output height
                {
                    for (int w = 0; w < output.GetLength(2); w++) // output width (number of characters)
                    {
                        int maxIndex = 0;
                        float maxValue = 0;
                        for (int c = 0; c < output.GetLength(2); c++)
                        {
                            if (output[b, h, c] > maxValue)
                            {
                                maxIndex = c;
                                maxValue = output[b, h, c];
                            }
                        }

                        char predictedChar = (char)maxIndex;
                        extractedText += predictedChar;
                    }
                }
            }

            return extractedText;
        }
    }` 












here's the error:
`An error occurred while performing OCR: System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.ML.Data.TypedCursorable`1.TypedRowBase.<>c__DisplayClass8_0`1.<CreateDirectVBufferSetter>b__0(TRow row)
   at Microsoft.ML.Data.TypedCursorable`1.TypedRowBase.FillValues(TRow row)
   at Microsoft.ML.Data.TypedCursorable`1.RowImplementation.FillValues(TRow row)
   at Microsoft.ML.PredictionEngineBase`2.FillValues(TDst prediction)
   at Microsoft.ML.PredictionEngine`2.Predict(TSrc example, TDst& prediction)
   at Microsoft.ML.PredictionEngineBase`2.Predict(TSrc example)
   at OcrSolution.API.Controllers.OcrController.PerformOCR(IFormFile imageFile) in C:\Users\k.mimouni\Desktop\ocr web app\sw-kamilia-2023\components\Server\OcrSolution.API\Controllers\OcrController.cs:line 95`<|||||>my onnx model from this link https://github.com/JaidedAI/EasyOCR/issues/786