Develop Reference

Bitmap.Clone(Rectangle, PixelFormat) - OutOfMemoryException [duplicate]

Why am I getting an out of memory exception?
So this dies in C# on the first time through:
splitBitmaps.Add(neededImage.Clone(rectDimensions, neededImage.PixelFormat));
Where splitBitmaps is a List<BitMap> BUT this works in VB for at least 4 iterations:
arlSplitBitmaps.Add(Image.Clone(rectDimensions, Image.PixelFormat))
Where arlSplitBitmaps is a simple array list. (And yes I've tried arraylist in c#)
This is the fullsection:
for (Int32 splitIndex = 0; splitIndex <= numberOfResultingImages - 1; splitIndex++)
{
Rectangle rectDimensions;
if (splitIndex < numberOfResultingImages - 1)
{
rectDimensions = new Rectangle(splitImageWidth * splitIndex, 0,
splitImageWidth, splitImageHeight);
}
else
{
rectDimensions = new Rectangle(splitImageWidth * splitIndex, 0,
sourceImageWidth - (splitImageWidth * splitIndex), splitImageHeight);
}
splitBitmaps.Add(neededImage.Clone(rectDimensions, neededImage.PixelFormat));
}
neededImage is a Bitmap by the way.
I can't find any useful answers on the intarweb, especially not why it works just fine in VB.
Update:
I actually found a reason (sort of) for this working but forgot to post it. It has to do with converting the image to a bitmap instead of just trying to clone the raw image if I remember.

Clone() may also throw an Out of memory exception when the coordinates specified in the Rectangle are outside the bounds of the bitmap. It will not clip them automatically for you.

I found that I was using Image.Clone to crop a bitmap and the width took the crop outside the bounds of the original image. This causes an Out of Memory error. Seems a bit strange but can beworth knowing.

I got this too when I tried to use the Clone() method to change the pixel format of a bitmap. If memory serves, I was trying to convert a 24 bpp bitmap to an 8 bit indexed format, naively hoping that the Bitmap class would magically handle the palette creation and so on. Obviously not :-/

This is a reach, but I've often found that if pulling images directly from disk that it's better to copy them to a new bitmap and dispose of the disk-bound image. I've seen great improvement in memory consumption when doing so.
Dave M. is on the money too... make sure to dispose when finished.

I struggled to figure this out recently - the answers above are correct. Key to solving this issue is to ensure the rectangle is actually within the boundaries of the image. See example of how I solved this.
In a nutshell, checked to if the area that was being cloned was outside the area of the image.
int totalWidth = rect.Left + rect.Width; //think -the same as Right property
int allowableWidth = localImage.Width - rect.Left;
int finalWidth = 0;
if (totalWidth > allowableWidth){
finalWidth = allowableWidth;
} else {
finalWidth = totalWidth;
}
rect.Width = finalWidth;
int totalHeight = rect.Top + rect.Height; //think same as Bottom property
int allowableHeight = localImage.Height - rect.Top;
int finalHeight = 0;
if (totalHeight > allowableHeight){
finalHeight = allowableHeight;
} else {
finalHeight = totalHeight;
}
rect.Height = finalHeight;
cropped = ((Bitmap)localImage).Clone(rect, System.Drawing.Imaging.PixelFormat.DontCare);

Make sure that you're calling .Dispose() properly on your images, otherwise unmanaged resources won't be freed up. I wonder how many images are you actually creating here -- hundreds? Thousands?

c# screen transfer over socket efficient improve ways

thats how i wrote your beautiful code(some simple changes for me for easier understanding)
private void Form1_Load(object sender, EventArgs e)
{
prev = GetDesktopImage();//get a screenshot of the desktop;
cur = GetDesktopImage();//get a screenshot of the desktop;
var locked1 = cur.LockBits(new Rectangle(0, 0, cur.Width, cur.Height),
ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
var locked2 = prev.LockBits(new Rectangle(0, 0, prev.Width, prev.Height),
ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
ApplyXor(locked1, locked2);
compressionBuffer = new byte[1920* 1080 * 4];
// Compressed buffer -- where the data goes that we'll send.
int backbufSize = LZ4.LZ4Codec.MaximumOutputLength(this.compressionBuffer.Length) + 4;
backbuf = new CompressedCaptureScreen(backbufSize);
MessageBox.Show(compressionBuffer.Length.ToString());
int length = Compress();
MessageBox.Show(backbuf.Data.Length.ToString());//prints the new buffer size
}
the compression buffer length is for example 8294400
and the backbuff.Data.length is 8326947

I didn't like the compression suggestions, so here's what I would do.
You don't want to compress a video stream (so MPEG, AVI, etc are out of the question -- these don't have to be real-time) and you don't want to compress individual pictures (since that's just stupid).
Basically what you want to do is detect if things change and send the differences. You're on the right track with that; most video compressors do that. You also want a fast compression/decompression algorithm; especially if you go to more FPS that will become more relevant.
Differences. First off, eliminate all branches in your code, and make sure memory access is sequential (e.g. iterate x in the inner loop). The latter will give you cache locality. As for the differences, I'd probably use a 64-bit XOR; it's easy, branchless and fast.
If you want performance, it's probably better to do this in C++: The current C# implementation doesn't vectorize your code, and that will help you a great deal here.
Do something like this (I'm assuming 32bit pixel format):
for (int y=0; y<height; ++y) // change to PFor if you like
{
ulong* row1 = (ulong*)(image1BasePtr + image1Stride * y);
ulong* row2 = (ulong*)(image2BasePtr + image2Stride * y);
for (int x=0; x<width; x += 2)
row2[x] ^= row1[x];
}
Fast compression and decompression usually means simpler compression algorithms. https://code.google.com/p/lz4/ is such an algorithm, and there's a proper .NET port available for that as well. You might want to read on how it works too; there is a streaming feature in LZ4 and if you can make it handle 2 images instead of 1 that will probably give you a nice compression boost.
All in all, if you're trying to compress white noise, it simply won't work and your frame rate will drop. One way to solve this is to reduce the colors if you have too much 'randomness' in a frame. A measure for randomness is entropy, and there are several ways to get a measure of the entropy of a picture ( https://en.wikipedia.org/wiki/Entropy_(information_theory) ). I'd stick with a very simple one: check the size of the compressed picture -- if it's above a certain limit, reduce the number of bits; if below, increase the number of bits.
Note that increasing and decreasing bits is not done with shifting in this case; you don't need your bits to be removed, you simply need your compression to work better. It's probably just as good to use a simple 'AND' with a bitmask. For example, if you want to drop 2 bits, you can do it like this:
for (int y=0; y<height; ++y) // change to PFor if you like
{
ulong* row1 = (ulong*)(image1BasePtr + image1Stride * y);
ulong* row2 = (ulong*)(image2BasePtr + image2Stride * y);
ulong mask = 0xFFFCFCFCFFFCFCFC;
for (int x=0; x<width; x += 2)
row2[x] = (row2[x] ^ row1[x]) & mask;
}
PS: I'm not sure what I would do with the alpha component, I'll leave that up to your experimentation.
Good luck!
The long answer
I had some time to spare, so I just tested this approach. Here's some code to support it all.
This code normally run over 130 FPS with a nice constant memory pressure on my laptop, so the bottleneck shouldn't be here anymore. Note that you need LZ4 to get this working and that LZ4 is aimed at high speed, not high compression ratio's. A bit more on that later.
First we need something that we can use to hold all the data we're going to send. I'm not implementing the sockets stuff itself here (although that should be pretty simple using this as a start), I mainly focused on getting the data you need to send something over.
// The thing you send over a socket
public class CompressedCaptureScreen
{
public CompressedCaptureScreen(int size)
{
this.Data = new byte[size];
this.Size = 4;
}
public int Size;
public byte[] Data;
}
We also need a class that will hold all the magic:
public class CompressScreenCapture
{
Next, if I'm running high performance code, I make it a habit to preallocate all the buffers first. That'll save you time during the actual algorithmic stuff. 4 buffers of 1080p is about 33 MB, which is fine - so let's allocate that.
public CompressScreenCapture()
{
// Initialize with black screen; get bounds from screen.
this.screenBounds = Screen.PrimaryScreen.Bounds;
// Initialize 2 buffers - 1 for the current and 1 for the previous image
prev = new Bitmap(screenBounds.Width, screenBounds.Height, PixelFormat.Format32bppArgb);
cur = new Bitmap(screenBounds.Width, screenBounds.Height, PixelFormat.Format32bppArgb);
// Clear the 'prev' buffer - this is the initial state
using (Graphics g = Graphics.FromImage(prev))
{
g.Clear(Color.Black);
}
// Compression buffer -- we don't really need this but I'm lazy today.
compressionBuffer = new byte[screenBounds.Width * screenBounds.Height * 4];
// Compressed buffer -- where the data goes that we'll send.
int backbufSize = LZ4.LZ4Codec.MaximumOutputLength(this.compressionBuffer.Length) + 4;
backbuf = new CompressedCaptureScreen(backbufSize);
}
private Rectangle screenBounds;
private Bitmap prev;
private Bitmap cur;
private byte[] compressionBuffer;
private int backbufSize;
private CompressedCaptureScreen backbuf;
private int n = 0;
First thing to do is capture the screen. This is the easy part: simply fill the bitmap of the current screen:
private void Capture()
{
// Fill 'cur' with a screenshot
using (var gfxScreenshot = Graphics.FromImage(cur))
{
gfxScreenshot.CopyFromScreen(screenBounds.X, screenBounds.Y, 0, 0, screenBounds.Size, CopyPixelOperation.SourceCopy);
}
}
As I said, I don't want to compress 'raw' pixels. Instead, I'd much rather compress XOR masks of previous and the current image. Most of the times this will give you a whole lot of 0's, which is easy to compress:
private unsafe void ApplyXor(BitmapData previous, BitmapData current)
{
byte* prev0 = (byte*)previous.Scan0.ToPointer();
byte* cur0 = (byte*)current.Scan0.ToPointer();
int height = previous.Height;
int width = previous.Width;
int halfwidth = width / 2;
fixed (byte* target = this.compressionBuffer)
{
ulong* dst = (ulong*)target;
for (int y = 0; y < height; ++y)
{
ulong* prevRow = (ulong*)(prev0 + previous.Stride * y);
ulong* curRow = (ulong*)(cur0 + current.Stride * y);
for (int x = 0; x < halfwidth; ++x)
{
*(dst++) = curRow[x] ^ prevRow[x];
}
}
}
}
For the compression algorithm I simply pass the buffer to LZ4 and let it do its magic.
private int Compress()
{
// Grab the backbuf in an attempt to update it with new data
var backbuf = this.backbuf;
backbuf.Size = LZ4.LZ4Codec.Encode(
this.compressionBuffer, 0, this.compressionBuffer.Length,
backbuf.Data, 4, backbuf.Data.Length-4);
Buffer.BlockCopy(BitConverter.GetBytes(backbuf.Size), 0, backbuf.Data, 0, 4);
return backbuf.Size;
}
One thing to note here is that I make it a habit to put everything in my buffer that I need to send over the TCP/IP socket. I don't want to move data around if I can easily avoid it, so I'm simply putting everything that I need on the other side there.
As for the sockets itself, you can use a-sync TCP sockets here (I would), but if you do, you will need to add an extra buffer.
The only thing that remains is to glue everything together and put some statistics on the screen:
public void Iterate()
{
Stopwatch sw = Stopwatch.StartNew();
// Capture a screen:
Capture();
TimeSpan timeToCapture = sw.Elapsed;
// Lock both images:
var locked1 = cur.LockBits(new Rectangle(0, 0, cur.Width, cur.Height),
ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
var locked2 = prev.LockBits(new Rectangle(0, 0, prev.Width, prev.Height),
ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
try
{
// Xor screen:
ApplyXor(locked2, locked1);
TimeSpan timeToXor = sw.Elapsed;
// Compress screen:
int length = Compress();
TimeSpan timeToCompress = sw.Elapsed;
if ((++n) % 50 == 0)
{
Console.Write("Iteration: {0:0.00}s, {1:0.00}s, {2:0.00}s " +
"{3} Kb => {4:0.0} FPS \r",
timeToCapture.TotalSeconds, timeToXor.TotalSeconds,
timeToCompress.TotalSeconds, length / 1024,
1.0 / sw.Elapsed.TotalSeconds);
}
// Swap buffers:
var tmp = cur;
cur = prev;
prev = tmp;
}
finally
{
cur.UnlockBits(locked1);
prev.UnlockBits(locked2);
}
}
Note that I reduce Console output to ensure that's not the bottleneck. :-)
Simple improvements
It's a bit wasteful to compress all those 0's, right? It's pretty easy to track the min and max y position that has data using a simple boolean.
ulong tmp = curRow[x] ^ prevRow[x];
*(dst++) = tmp;
hasdata |= tmp != 0;
You also probably don't want to call Compress if you don't have to.
After adding this feature you'll get something like this on your screen:
Iteration: 0.00s, 0.01s, 0.01s 1 Kb => 152.0 FPS
Using another compression algorithm might also help. I stuck to LZ4 because it's simple to use, it's blazing fast and compresses pretty well -- still, there are other options that might work better. See http://fastcompression.blogspot.nl/ for a comparison.
If you have a bad connection or if you're streaming video over a remote connection, all this won't work. Best to reduce the pixel values here. That's quite simple: apply a simple 64-bit mask during the xor to both the previous and current picture... You can also try using indexed colors - anyhow, there's a ton of different things you can try here; I just kept it simple because that's probably good enough.
You can also use Parallel.For for the xor loop; personally I didn't really care about that.
A bit more challenging
If you have 1 server that is serving multiple clients, things will get a bit more challenging, as they will refresh at different rates. We want the fastest refreshing client to determine the server speed - not slowest. :-)
To implement this, the relation between the prev and cur has to change. If we simply 'xor' away like here, we'll end up with a completely garbled picture at the slower clients.
To solve that, we don't want to swap prev anymore, as it should hold key frames (that you'll refresh when the compressed data becomes too big) and cur will hold incremental data from the 'xor' results. This means you can basically grab an arbitrary 'xor'red frame and send it over the line - as long as the prev bitmap is recent.

H264 or Equaivalent Codec Streaming
There are various compressed streaming available which does almost everything that you can do to optimize screen sharing over network. There are many open source and commercial libraries to stream.
Screen transfer in Blocks
H264 already does this, but if you want to do it yourself, you have to divide your screens into smaller blocks of 100x100 pixels, and compare these blocks with previous version and send these blocks over network.
Window Render Information
Microsoft RDP does lot better, it does not send screen as a raster image, instead it analyzes screen and creates screen blocks based on the windows on the screen. It then analyzes contents of screen and sends image only if needed, if it is a text box with some text in it, RDP sends information to render text box with a text with font information and other information. So instead of sending image, it sends information on what to render.
You can combine all techniques and make a mixed protocol to send screen blocks with image and other rendering information.

Instead of handling data as an array of bytes, you can handle it as an array of integers.
int* p = (int*)((byte*)scan0.ToPointer() + y * stride);
int* p2 = (int*)((byte*)scan02.ToPointer() + y * stride2);
for (int x = 0; x < nWidth; x++)
{
//always get the complete pixel when differences are found
if (*p2 != 0)
*p = *p2
++p;
++p2;
}

Access preview frame from MediaCapture

I would like to grab the preview frames that are displayed inside my CaptureElement xaml element. The source of my CaptureElement is set to a MediaCapture object and I use the StartPreview() method to start displaying the camera. I would like to access the frames that are being shown without saving them to an img or video file. The goal is to capture 10 fps from the preview and send each frame to another class that accepts byte[].
I tried using the CapturePhotoToStorageFileAsync method however this is not a feasible option as I do not want to take 10 actual images / second. I also do not want to use ScreenCapture as it stores what is captured into a video file. Ideally I do not want to store any media files temporarily on the phone. After looking at the msdn for MediaCapture, I noticed there's a method called GetPreviewFrameAsync() however this method does not exist inside Windows Phone 8.1. I also stumbled on this example however I do not completely understand how it works.
Any suggestions on how to approach this is greatly appreciated.

There is a sample on the Microsoft github page that is relevant, although they target Windows 10. You may be interested in migrating your project to get this functionality.
GetPreviewFrame: This sample will capture preview frames as opposed to full-blown photos. Once it has a preview frame, it can edit the pixels on it.
Here is the relevant part:
private async Task GetPreviewFrameAsSoftwareBitmapAsync()
{
// Get information about the preview
var previewProperties = _mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview) as VideoEncodingProperties;
// Create the video frame to request a SoftwareBitmap preview frame
var videoFrame = new VideoFrame(BitmapPixelFormat.Bgra8, (int)previewProperties.Width, (int)previewProperties.Height);
// Capture the preview frame
using (var currentFrame = await _mediaCapture.GetPreviewFrameAsync(videoFrame))
{
// Collect the resulting frame
SoftwareBitmap previewFrame = currentFrame.SoftwareBitmap;
// Add a simple green filter effect to the SoftwareBitmap
EditPixels(previewFrame);
}
}
private unsafe void EditPixels(SoftwareBitmap bitmap)
{
// Effect is hard-coded to operate on BGRA8 format only
if (bitmap.BitmapPixelFormat == BitmapPixelFormat.Bgra8)
{
// In BGRA8 format, each pixel is defined by 4 bytes
const int BYTES_PER_PIXEL = 4;
using (var buffer = bitmap.LockBuffer(BitmapBufferAccessMode.ReadWrite))
using (var reference = buffer.CreateReference())
{
// Get a pointer to the pixel buffer
byte* data;
uint capacity;
((IMemoryBufferByteAccess)reference).GetBuffer(out data, out capacity);
// Get information about the BitmapBuffer
var desc = buffer.GetPlaneDescription(0);
// Iterate over all pixels
for (uint row = 0; row < desc.Height; row++)
{
for (uint col = 0; col < desc.Width; col++)
{
// Index of the current pixel in the buffer (defined by the next 4 bytes, BGRA8)
var currPixel = desc.StartIndex + desc.Stride * row + BYTES_PER_PIXEL * col;
// Read the current pixel information into b,g,r channels (leave out alpha channel)
var b = data[currPixel + 0]; // Blue
var g = data[currPixel + 1]; // Green
var r = data[currPixel + 2]; // Red
// Boost the green channel, leave the other two untouched
data[currPixel + 0] = b;
data[currPixel + 1] = (byte)Math.Min(g + 80, 255);
data[currPixel + 2] = r;
}
}
}
}
}
And declare this outside your class:
[ComImport]
[Guid("5b0d3235-4dba-4d44-865e-8f1d0e4fd04d")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
unsafe interface IMemoryBufferByteAccess
{
void GetBuffer(out byte* buffer, out uint capacity);
}
And of course, your project will have to allow unsafe code for all of this to work.
Have a closer look at the sample to see how to get all the details. Or, to have a walkthrough, you can watch the camera session from the recent //build/ conference, which includes a little bit of a walkthrough through some camera samples.

Kinect V2 Color Stream Byte Order

I'm working on an application which will stream the color, depth, and IR video data from the Kinect V2 sensor. Right now I'm just putting together the color video part of the app. I've read through some tutorials and actually got some video data coming into my app - the problem seems to be that the byte order seems to be in the wrong order which gives me an oddly discolored image (see below).
So, let me explain how I got here. In my code, I first open the sensor and also instantiate a new multi source frame reader. After I've created the reader, I create an event handler called Reader_MultiSourceFrameArrived:
void Reader_MultiSourceFrameArrived(object sender, MultiSourceFrameArrivedEventArgs e)
{
if (proccessing || gotframe) return;
// Get a reference to the multi-frame
var reference = e.FrameReference.AcquireFrame();
// Open color frame
using (ColorFrame frame = reference.ColorFrameReference.AcquireFrame())
{
if (frame != null)
{
proccessing = true;
var description = frame.ColorFrameSource.FrameDescription;
bw2 = description.Width / 2;
bh2 = description.Height / 2;
bpp = (int)description.BytesPerPixel;
if (imgBuffer == null)
{
imgBuffer = new byte[description.BytesPerPixel * description.Width * description.Height];
}
frame.CopyRawFrameDataToArray(imgBuffer);
gotframe = true;
proccessing = false;
}
}
}
Now, every time a frame is received (and not processing) it should copy the frame data into an array called imgBuffer. When my application is ready I then call this routine to convert the array into a Windows Bitmap that I can display on my screen.
if (gotframe)
{
if (theBitmap.Rx != bw2 || theBitmap.Ry != bh2) theBitmap.SetSize(bw2, bh2);
int kk = 0;
for (int j = 0; j < bh2; ++j)
{
for (int i = 0; i < bw2; ++i)
{
kk = (j * bw2 * 2 + i) * 2 * bpp;
theBitmap.pixels[i, bh2 - j - 1].B = imgBuffer[kk];
theBitmap.pixels[i, bh2 - j - 1].G = imgBuffer[kk + 1];
theBitmap.pixels[i, bh2 - j - 1].R = imgBuffer[kk + 2];
theBitmap.pixels[i, bh2 - j - 1].A = 255;
}
}
theBitmap.needupdate = true;
gotframe = false;
}
}
So, after this runs theBitmap now contains the image information needed to draw the image on the screen... however, as seen in the image above - it looks quite strange. The most obvious change is to simply change the order of the pixel B,G,R values when they get assigned to the bitmap in the double for loop (which I tried)... however, this simply results in other strange color images and none provide an accurate color image. Any thoughts where I might be going wrong?

Is this Bgra?
The normal "RGB" in Kinect v2 for C# is BGRA.
Using the Kinect SDK 2.0, you don't need all of those "for" cycles.
The function used to allocate the pixels in the bitmap is this one:
colorFrame.CopyConvertedFrameDataToIntPtr(
this.colorBitmap.BackBuffer,
(uint)(colorFrameDescription.Width * colorFrameDescription.Height * 4),
ColorImageFormat.Bgra);
1) Get the Frame From the kinect, using Reader_ColorFrameArrived (go see ColorSamples - WPF);
2) Create the colorFrameDescription from the ColorFrameSource using Bgra format;
3) Create the bitmap to display;
If you have any problems, please say. But if you follow the sample it's actually pretty clean there how to do it.

I was stuck on this problem forever. Problem is, that all almost all examples you find, are WPF examples. But for Windows Forms its a different story.
frame.CopyRawFrameDataToArray(imgBuffer);
gets you the rawdata whitch is
ColorImageFormat.Yuy2
By converting it to RGB you should be able to fix your color problem. The transformation from YUY2 to RGB is very expensive, you might want to use a Parallel foreach loop to maintain your framerate

How can you copy part of a writeablebitmap to another writeablebitmap?

How would you copy a part from one WriteableBitmap to another WriteableBitmap? I've written and used dozens of 'copypixel' and transparent copies in the past, but I can't seem to find the equivalent for WPF C#.
This is either the most difficult question in the world or the easiest because absolutely nobody is touching it with a ten foot pole.

Use WriteableBitmapEx from http://writeablebitmapex.codeplex.com/
Then use the Blit method as below.
private WriteableBitmap bSave;
private WriteableBitmap bBase;
private void test()
{
bSave = BitmapFactory.New(200, 200); //your destination
bBase = BitmapFactory.New(200, 200); //your source
//here paint something on either bitmap.
Rect rec = new Rect(0, 0, 199, 199);
using (bSave.GetBitmapContext())
{
using (bBase.GetBitmapContext())
{
bSave.Blit(rec, bBase, rec, WriteableBitmapExtensions.BlendMode.Additive);
}
}
}
you can use BlendMode.None for higher performance if you don't need to preserve any information in your destination. When using Additive you get alpha compositing between source and destination.

There does not appear to be a way to copy directly from one to another but you can do it in two steps using an array and CopyPixels to get them out of one and then WritePixels to get them into another.

I agree with Guy above that the easiest method is to simply use the WriteableBitmapEx library; however, the Blit function is for compositing a foreground and background image. The most efficient method to copy a part of one WriteableBitmap to another WriteableBitmap would be to use the Crop function:
var DstImg = SrcImg.Crop(new Rect(...));
Note that your SrcImg WriteableBitmap must be in the Pbgra32 format to be operated on by the WriteableBitmapEx library. If your bitmap isn't in this form, then you can easily convert it before cropping:
var tmp = BitmapFactory.ConvertToPbgra32Format(SrcImg);
var DstImg = tmp.Crop(new Rect(...));

public static void CopyPixelsTo(this BitmapSource sourceImage, Int32Rect sourceRoi, WriteableBitmap destinationImage, Int32Rect destinationRoi)
{
var croppedBitmap = new CroppedBitmap(sourceImage, sourceRoi);
int stride = croppedBitmap.PixelWidth * (croppedBitmap.Format.BitsPerPixel / 8);
var data = new byte[stride * croppedBitmap.PixelHeight];
// Is it possible to Copy directly from the sourceImage into the destinationImage?
croppedBitmap.CopyPixels(data, stride, 0);
destinationImage.WritePixels(destinationRoi,data,stride,0);
}