Creating a Byte array from an Image

Question

What is the best way to create a byte array from an Image? I have seen many methods but in WinRT none of them worked.

was this [Charles Petzold article] (charlespetzold.com/blog/2012/08/…) one that you tried? — Jim O'Neil
– Jim O'Neil, Commented Feb 21, 2013 at 16:08

Manic · Accepted Answer · 2013-03-12 10:26:45Z

2

static class ByteArrayConverter
    {
        public static async Task<byte[]> ToByteArrayAsync(StorageFile file)
        {
            using (IRandomAccessStream stream = await file.OpenReadAsync())
            {
                using (DataReader reader = new DataReader(stream.GetInputStreamAt(0)))
                {
                    await reader.LoadAsync((uint)stream.Size);
                    byte[] Bytes = new byte[stream.Size];
                    reader.ReadBytes(Bytes);
                    return Bytes;
                }
            }
        }
    }

answered Mar 12, 2013 at 10:26

Manic

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Comments

Hermit Dave · Accepted Answer · 2013-02-21 15:38:36Z

2

here is one way http://msdn.microsoft.com/en-us/library/windows/apps/windows.ui.xaml.media.imaging.writeablebitmap.aspx

alternatively if you have the Image saved on FS, just create a StorageFile and use the stream to get byte[]

answered Feb 21, 2013 at 15:38

Hermit Dave

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Comments

JP Alioto · Accepted Answer · 2013-02-22 04:41:17Z

1

The magic is in the DataReader class. For example ...

var file = await Windows.Storage.StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/Logo.png"));
var buf = await FileIO.ReadBufferAsync(file);
var bytes = new byte[buf.Length];
var dr = DataReader.FromBuffer(buf);
dr.ReadBytes(bytes);

answered Feb 22, 2013 at 4:41

JP Alioto

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2 Comments

thumbmunkeys Over a year ago

i guess he meant reading the pixel data, not the file contents

Jim O'Neil Over a year ago

thought the same thing... BUT in order to get the pixel data you have to reload the Image (capital "I") into a WriteableBitmap, and if you're doing that why not just read the source directly as @JP mentioned!

Kristian Vukusic · Accepted Answer · 2013-02-22 16:09:25Z

I have used the method from Charles Petzold:

        byte[] srcPixels;
        Uri uri = new Uri("http://www.skrenta.com/images/stackoverflow.jpg");
        RandomAccessStreamReference streamRef = RandomAccessStreamReference.CreateFromUri(uri);

        using (IRandomAccessStreamWithContentType fileStream = await streamRef.OpenReadAsync())
        {
            BitmapDecoder decoder = await BitmapDecoder.CreateAsync(fileStream);
            BitmapFrame frame = await decoder.GetFrameAsync(0);

            PixelDataProvider pixelProvider = await frame.GetPixelDataAsync();
            srcPixels = pixelProvider.DetachPixelData();

        }

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