Get-Win10OcrTextFromImage.ps1

using namespace Windows.Storage
using namespace Windows.Graphics.Imaging

<#
.Synopsis
   Runs Windows 10 OCR on an image.
.DESCRIPTION
   Takes a path to an image file, with some text on it.
   Runs Windows 10 OCR against the image.
   Returns an [OcrResult], hopefully with a .Text property containing the text
.EXAMPLE
   $result = .\Get-Win10OcrTextFromImage.ps1 -Path 'c:\test.bmp'
   $result.Text
#>
[CmdletBinding()]
Param
(
    # Path to an image file
    [Parameter(Mandatory=$true, 
                ValueFromPipeline=$true,
                ValueFromPipelineByPropertyName=$true, 
                Position=0,
                HelpMessage='Path to an image file, to run OCR on')]
    [ValidateNotNullOrEmpty()]
    $Path
)

Begin {
    # Add the WinRT assembly, and load the appropriate WinRT types
    Add-Type -AssemblyName System.Runtime.WindowsRuntime

    $null = [Windows.Storage.StorageFile,                Windows.Storage,         ContentType = WindowsRuntime]
    $null = [Windows.Media.Ocr.OcrEngine,                Windows.Foundation,      ContentType = WindowsRuntime]
    $null = [Windows.Foundation.IAsyncOperation`1,       Windows.Foundation,      ContentType = WindowsRuntime]
    $null = [Windows.Graphics.Imaging.SoftwareBitmap,    Windows.Foundation,      ContentType = WindowsRuntime]
    $null = [Windows.Storage.Streams.RandomAccessStream, Windows.Storage.Streams, ContentType = WindowsRuntime]
    
    
    # [Windows.Media.Ocr.OcrEngine]::AvailableRecognizerLanguages
    $ocrEngine = [Windows.Media.Ocr.OcrEngine]::TryCreateFromUserProfileLanguages()
    

    # PowerShell doesn't have built-in support for Async operations, 
    # but all the WinRT methods are Async.
    # This function wraps a way to call those methods, and wait for their results.
    $getAwaiterBaseMethod = [WindowsRuntimeSystemExtensions].GetMember('GetAwaiter').
                                Where({
                                        $PSItem.GetParameters()[0].ParameterType.Name -eq 'IAsyncOperation`1'
                                    }, 'First')[0]

    Function Await {
        param($AsyncTask, $ResultType)

        $getAwaiterBaseMethod.
            MakeGenericMethod($ResultType).
            Invoke($null, @($AsyncTask)).
            GetResult()
    }
}

Process
{
    foreach ($p in $Path)
    {
      
        # From MSDN, the necessary steps to load an image are:
        # Call the OpenAsync method of the StorageFile object to get a random access stream containing the image data.
        # Call the static method BitmapDecoder.CreateAsync to get an instance of the BitmapDecoder class for the specified stream. 
        # Call GetSoftwareBitmapAsync to get a SoftwareBitmap object containing the image.
        #
        # https://docs.microsoft.com/en-us/windows/uwp/audio-video-camera/imaging#save-a-softwarebitmap-to-a-file-with-bitmapencoder

        # .Net method needs a full path, or at least might not have the same relative path root as PowerShell
        $p = $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath($p)
        
        $params = @{ 
            AsyncTask  = [StorageFile]::GetFileFromPathAsync($p)
            ResultType = [StorageFile]
        }
        $storageFile = Await @params


        $params = @{ 
            AsyncTask  = $storageFile.OpenAsync([FileAccessMode]::Read)
            ResultType = [Streams.IRandomAccessStream]
        }
        $fileStream = Await @params


        $params = @{
            AsyncTask  = [BitmapDecoder]::CreateAsync($fileStream)
            ResultType = [BitmapDecoder]
        }
        $bitmapDecoder = Await @params


        $params = @{ 
            AsyncTask = $bitmapDecoder.GetSoftwareBitmapAsync()
            ResultType = [SoftwareBitmap]
        }
        $softwareBitmap = Await @params

        # Run the OCR
        Await $ocrEngine.RecognizeAsync($softwareBitmap) ([Windows.Media.Ocr.OcrResult])

    }
}