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How to keep EXIF of an edited image?

So my program is fixing some image artefacts, it goes like this:
void FixFile(string path)
{
var bmp = new WriteableBitmap(new BitmapImage(new Uri(path)));
bmp.Lock();
// magick
bmp.Unlock();
using (var stream = new FileStream(path.Replace("DSC", "fix_DSC"), FileMode.Create))
{
var encoder = new JpegBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bmp));
encoder.Save(stream);
}
}
The problem is that fixed image contains no EXIF data. How do I transfer EXIF data from the original image?

Load the source bitmap as BitmapFrame, not BitmapImage. Then pass the Metadata property of the source to the new BitmapFrame that is added to the Frames collection of the encoder.
public void FixFile(string path)
{
var source = BitmapFrame.Create(new Uri(path));
var metadata = (BitmapMetadata)source.Metadata;
var bmp = new WriteableBitmap(source);
bmp.Lock();
// magick
bmp.Unlock();
var target = BitmapFrame.Create(bmp, null, metadata, null); // here
var encoder = new JpegBitmapEncoder();
encoder.Frames.Add(target);
using (var stream = File.OpenWrite(path.Replace("DSC", "fix_DSC")))
{
encoder.Save(stream);
}
}

PDFiumSharp PDF to Image size

I am using PDFiumSharp to generate JPGs from PDF file. Here is my code:
using (WebClient client = new WebClient())
{
byte[] pdfData = await client.DownloadDataTaskAsync(pdfUrl);
using (var doc = new PdfDocument(pdfData))
{
int i = 0;
foreach (var page in doc.Pages)
{
using (var bitmap = new PDFiumBitmap((int)page.Width, (int)page.Height, true))
using (var stream = new MemoryStream())
{
page.Render(bitmap);
bitmap.Save(stream);
...
i++;
}
}
}
}
The codes work very well, images are generated accurately. However, each JPG is about 2mb. With multi-page PDF, the overall image size adds up quickly. Is there any way to reduce the JPG file size? I only need the JPG for preview purposes, not for printing. So lower resolution or quality is fine.

When you call bitmap.Save(...), the resulting byte[] that gets put into the MemoryStream stream represents a BMP. You should convert it into JPG yourself.
public static byte[] Render(PdfDocument pdfDocument, int pageNumber, (int width, int height) outputSize)
{
var page = pdfDocument.Pages[pageNumber];
using var thumb = new PDFiumBitmap((int)page.Width, (int)page.Height, false);
page.Render(thumb);
using MemoryStream memoryStreamBMP = new();
thumb.Save(memoryStreamBMP);
using Image imageBmp = Image.FromStream(memoryStreamBMP);
using MemoryStream memoryStreamJPG = new();
imageBmp.Save(memoryStreamJPG, ImageFormat.Jpeg);
return memoryStreamJPG.ToArray();
}

Cannot convert bitmap to byte[]

So I'm making a Xamarin.Forms app. I have a StackLayout, of which I'm taking a snapshot(only the element, not the whole screen.)
This is the interface:
public interface IViewSnapShot
{
Task<byte[]> CaptureAsync(Xamarin.Forms.View view);
}
this is the event:
private async Task SavePic_ClickedAsync(object sender, EventArgs e)
{
var imageByte = await DependencyService.Get<IViewSnapShot>().CaptureAsync(BlueprintSnapshot);
}
and this is Android platform specific:
public class MakeViewSnapshot : IViewSnapShot
{
Task<byte[]> IViewSnapShot.CaptureAsync(Xamarin.Forms.View view)
{
var nativeView = view.GetRenderer().View;
var wasDrawingCacheEnabled = nativeView.DrawingCacheEnabled;
nativeView.DrawingCacheEnabled = true;
nativeView.BuildDrawingCache(false);
Bitmap bitmap = nativeView.GetDrawingCache(false);
// TODO: Save bitmap and return filepath
nativeView.DrawingCacheEnabled = wasDrawingCacheEnabled;
byte[] bitmapData;
using (var stream = new MemoryStream())
{
bitmap.Compress(Bitmap.CompressFormat.Png, 0, stream);
bitmapData = stream.ToArray();
}
return bitmapData;
}
}
The problem is bitmapData gives error
Cannot implicitly convert type 'byte[]' to 'System.Threading.Tasks.Task'
I have search internet, and every post says that this is the way to convert bitmap to byte[] array. Any idea how to fix this error?
Later I'll want to upload the byte[] array to web api.

Instead of returning a byte[], you can use the Task.FromResult() to wrap a result into a Task:
return Task.FromResult(bitmapData);
Your code might looks like this:
public class MakeViewSnapshot : IViewSnapShot
{
Task<byte[]> IViewSnapShot.CaptureAsync(Xamarin.Forms.View view)
{
var nativeView = view.GetRenderer().View;
var wasDrawingCacheEnabled = nativeView.DrawingCacheEnabled;
nativeView.DrawingCacheEnabled = true;
nativeView.BuildDrawingCache(false);
Bitmap bitmap = nativeView.GetDrawingCache(false);
// TODO: Save bitmap and return filepath
nativeView.DrawingCacheEnabled = wasDrawingCacheEnabled;
byte[] bitmapData;
using (var stream = new MemoryStream())
{
bitmap.Compress(Bitmap.CompressFormat.Png, 0, stream);
bitmapData = stream.ToArray();
}
return Task.FromResult(bitmapData);
}
}
And then later when you want to get the byte[] returned by CaptureAsync() you just need to call:
byte[] result = CaptureAsync(<Your_parameters>).Result;

Sevenzipsharp CompressStream throws Exception: Value cannot be null

I am trying out following code in order to compress and save a bitmap of a screenshot but get this error. I haven't tried using CompressFiles as I have to do it using memory stream.
public void CompressAndSaveBitmap(Bitmap bitmap)
{
using (MemoryStream memStream = new MemoryStream())
{
using (FileStream file = new FileStream("XYZ", FileMode.Create, System.IO.FileAccess.Write))
{
bitmap.Save(memStream, System.Drawing.Imaging.ImageFormat.Bmp);
// tried these but they don't work.
//memStream.Seek(0, 0);
//memStream.Position = 0;
this.compressor.CompressStream(memStream, file); // throws error here
// also tried the following to see if Bitmap contains the problem
//UnicodeEncoding uniEncoding = new UnicodeEncoding();
//byte[] firstString = uniEncoding.GetBytes("Invalid file path characters are: ");
//int count = 0;
//while (count < firstString.Length)
//memStream.WriteByte(firstString[count++]);
//memStream.Flush();
////memStream.Seek(0, 0);
//memStream.Position = 0;
//this.compressor.CompressStream(memStream, file);
}
}
}
Compressor initialization code:
public Compressor()
{
SevenZipCompressor.SetLibraryPath(#"D:\7z.dll");
this.compressor = new SevenZip.SevenZipCompressor();
compressor.CompressionLevel = CompressionLevel.Ultra;
compressor.CompressionMethod = CompressionMethod.Ppmd;
}
It's crashes on this line in the library:
var lockObject = (object) _files ?? _streams;
lock (lockObject) // here in ArchiveUpdateCallback.cs
I see that the file is created but it's corrupt.

I was able to successfully compress file using following code:
public void CompressAndSaveBitmap(Bitmap bitmap)
{
using (MemoryStream memStream = new MemoryStream())
{
using (FileStream file = new FileStream("XYZ", FileMode.Create, System.IO.FileAccess.Write))
{
bitmap.Save(memStream, System.Drawing.Imaging.ImageFormat.Bmp);
// tried these but they don't work.
//memStream.Seek(0, 0);
//memStream.Position = 0;
SevenZipCompressor compressor =
new SevenZipCompressor
{
CompressionLevel = CompressionLevel.Ultra,
CompressionMethod = CompressionMethod.Lzma
};
compressor.CompressStream(memStream, file); // throws error here
}
}
}
Following was the bitmap file:
Executed code:
Bitmap bmp = new Bitmap("Test.bmp");
res.CompressAndSaveBitmap(bmp);
After execution got following output:
Opened the file with WinRar and extracted file:
In folder found the extracted image:
UPDATE:
I think the only problem with OP's code is this.compressor is not initialized.

BitMapImage to byte and reverse

Since two days I try to manage my images in a WPF application but I have errors and errors errors, ...
The image is show in a System.Windows.Control.Image.
For this reason I try to work with variable BitMapImage.
Now I have the error : "Impossible to access close stream" and I can not find a solution.
I have created two function for convert :
public static BitmapImage ConvertToBitMapImage(byte[] bytes)
{
if (bytes == null || bytes.Length == 0) return null;
var image = new BitmapImage();
using (var mem = new MemoryStream(bytes))
{
mem.Position = 0;
image.BeginInit();
image.CreateOptions = BitmapCreateOptions.PreservePixelFormat;
image.CacheOption = BitmapCacheOption.OnLoad;
image.UriSource = null;
image.StreamSource = mem;
image.EndInit();
}
//image.Freeze();
return image;
}
public static byte[] ImageToByte(BitmapImage imageSource)
{
Stream stream = imageSource.StreamSource;
Byte[] buffer = null;
if (stream != null && stream.Length > 0)
{
using (BinaryReader br = new BinaryReader(stream))
{
buffer = br.ReadBytes((Int32)stream.Length);
}
}
return buffer;
}
In my object I have a property :
public BitmapImage MiniatureApp
{
get
{
if (IMAGES != null)
_MiniatureApp = Tools.BinaryImageConverter.ConvertToBitMapImage(IMAGES.IMAGE);
return _MiniatureApp;
}
set
{
if (this.IMAGES != null)
this.IMAGES.IMAGE = Tools.BinaryImageConverter.ImageToByte((BitmapImage)value);
else
{
IMAGES img = new IMAGES();
img.NOM = "";
img.IMAGE = Tools.BinaryImageConverter.ImageToByte((BitmapImage)value);
this.IMAGES = img;
}
NotifyPropertyChanged();
}
}
And in my main I do this :
FileStream fs = new FileStream(pathImage, FileMode.Open, FileAccess.Read);
byte[] data = new byte[fs.Length];
fs.Read(data, 0, System.Convert.ToInt32(fs.Length));
fs.Close();
VMAppareil.VMApp.CurrentAppareil.MiniatureApp = Tools.BinaryImageConverter.ConvertToBitMapImage(data);
Exist a solution for my problem or exist a best way to do this ?
Gobelet.

You can fix your solution replacing the ImageToByte method with the following (borrowed from https://stackoverflow.com/a/6597746/5574010)
public static byte[] ImageToByte(BitmapImage imageSource)
{
var encoder = new JpegBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(imageSource));
using (var ms = new MemoryStream())
{
encoder.Save(ms);
return ms.ToArray();
}
}
Your previous solution did not work because the ConvertToBitMapImage method close the stream that you assign to image.StreamSource as soon as your code exit the unit statement. When you call the ImageToByte method as part of the MiniatureApp setter the StreamSource will be close and you get an error.

I'm not really sure what you're doing with the getter-setter.
For getting a byte array from a file, I would have this:
public static byte[] FileToByteArray(string fileName)
{
byte[] fileData = null;
using (FileStream fs = new File.OpenRead(fileName))
{
var binaryReader = new BinaryReader(fs);
fileData = binaryReader.ReadBytes((int)fs.Length);
}
return fileData;
}
And once you have the bytes from that function, you can use ConvertToBitMapImage() and assign that to the Image.Source, like this:
byte[] bytes = FileToByteArray(fileName);
YourImage.Source = ConvertToBitMapImage(bytes);
I'm not sure why you would need to convert a BitmapImage into bytes, but you should be able to call your function directly for that:
BitmapImage bImg = new BitmapImage();
bImg.Source = ConvertToBitMapImage(bytes);
byte[] bytes = ImageToByte(bImg); // these should be the same bytes as went in
Set it up like this and step through the code to see where it snags. It's possible the bytes might need encoding when you grab it in ImageToByte().
But also, you don't just then set the byte[] directly to the IMAGES or this.IMAGES.IMAGE, because that isn't an Image object, it's a byte[]. Without knowing what your IMAGES model construct looks like with its property types, it's a little vague to know what is being set to what and why, but this seems like a bad idea to over-complicate what you should just do with function calls as it is needed, without a getter-setter and an IMAGES model in the way.