Add FLIR sample code

Author: drewnoakes

MetadataExtractor.Samples/FlirSamples.cs

@@ -0,0 +1,113 @@
+// Copyright (c) Drew Noakes and contributors. All Rights Reserved. Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+using System.Diagnostics.CodeAnalysis;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using MetadataExtractor.Formats.Flir;
+using MetadataExtractor.Formats.Jpeg;
+using MetadataExtractor.Util;
+
+namespace MetadataExtractor.Samples
+{
+    public static class FlirSamples
+    {
+        public static void Main()
+        {
+            var inputFile = "my-input.jpg";   // path to a FLIR JPEG file
+            var outputFile = "my-output.png"; // path to the output thermal image
+
+            if (TryGetThermalImageBytesFromJpeg(inputFile, out byte[]? bytes, out int width, out int height))
+            {
+                WritePng(bytes, width, height, outputFile);
+            }
+        }
+
+        public static bool TryGetThermalImageBytesFromJpeg(
+            string jpegFile,
+            [NotNullWhen(returnValue: true)] out byte[]? imageBytes,
+            out int width,
+            out int height)
+        {
+            var readers = JpegMetadataReader
+                .AllReaders
+                .Where(reader => reader is not FlirReader)
+                .Concat(new[] { new FlirReader { ExtractRawThermalImage = true } })
+                .ToList();
+
+            var directories = JpegMetadataReader.ReadMetadata(jpegFile, readers);
+
+            var flirRawDataDirectory = directories.OfType<FlirRawDataDirectory>().FirstOrDefault();
+
+            if (flirRawDataDirectory is null)
+            {
+                imageBytes = null;
+                width = 0;
+                height = 0;
+                return false;
+            }
+
+            width = flirRawDataDirectory.GetInt32(FlirRawDataDirectory.TagRawThermalImageWidth);
+            height = flirRawDataDirectory.GetInt32(FlirRawDataDirectory.TagRawThermalImageHeight);
+            imageBytes = flirRawDataDirectory.GetByteArray(FlirRawDataDirectory.TagRawThermalImage);
+
+            return imageBytes != null;
+        }
+
+        public static void WritePng(byte[] thermalImageBytes, int width, int height, string outputFile)
+        {
+            var fileType = FileTypeDetector.DetectFileType(new MemoryStream(thermalImageBytes));
+
+            if (fileType == FileType.Png)
+            {
+                // Data is already in PNG format.
+                // It is likely already coloured and ready for presentation to a human.
+
+                File.WriteAllBytes(outputFile, thermalImageBytes);
+                return;
+            }
+
+            // Assume data is in uint16 grayscale.
+            //
+            // It is "raw" meaning uncoloured but, more importantly, the levels are unadjusted.
+            // For example, if the scene did not have much temperature variation relative to the
+            // range of the sensor, most values may be within a very narrow band of the 16-bit spectrum,
+            // making the image appear a flat gray. Opening it in Photoshop/Gimp/etc and adjusting levels
+            // will reveal the image.
+            //
+            // There is other metadata in the image that may inform this process (untested -- please
+            // share if you find a good process here).
+
+            var pixelFormats = PixelFormats.Gray16;
+
+            var bitmap = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format16bppGrayScale);
+
+            var data = bitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, bitmap.PixelFormat);
+
+            Marshal.Copy(thermalImageBytes, 0, data.Scan0, thermalImageBytes.Length);
+
+            var source = BitmapSource.Create(
+                width,
+                height,
+                bitmap.HorizontalResolution,
+                bitmap.VerticalResolution,
+                pixelFormats,
+                null,
+                data.Scan0,
+                data.Stride * height,
+                data.Stride);
+
+            bitmap.UnlockBits(data);
+
+            using var stream = new FileStream(outputFile, FileMode.Create);
+
+            var encoder = new PngBitmapEncoder();
+            encoder.Frames.Add(BitmapFrame.Create(source));
+            encoder.Save(stream);
+        }
+    }
+}

MetadataExtractor.Samples/MetadataExtractor.Samples.csproj

@@ -1,21 +1,25 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net5.0;net35;net45</TargetFrameworks>
+    <TargetFramework>net48</TargetFramework>
     <OutputType>Exe</OutputType>
+    <StartupObject>MetadataExtractor.Samples.Program</StartupObject>
   </PropertyGroup>
 
   <ItemGroup>
     <ProjectReference Include="..\MetadataExtractor\MetadataExtractor.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition=" '$(TargetFramework)' == 'net35' ">
-    <Reference Include="System" />
+  <ItemGroup>
+    <PackageReference Include="Nullable" Version="1.3.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
+    </PackageReference>
   </ItemGroup>
 
-  <ItemGroup Condition=" '$(TargetFramework)' == 'net45' ">
-    <Reference Include="System" />
-    <Reference Include="Microsoft.CSharp" />
+  <ItemGroup>
+    <Reference Include="PresentationCore" />
+    <Reference Include="WindowsBase" />
   </ItemGroup>
 
 </Project>