Hi All,
I am pretty new to bitmap manipulations. I have a byte array and i need a bitmap out of that. I am using the below code to get the bitmap.
if (imgByte != null)
{
BitmapData bmpData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.WriteOnly, bmp.PixelFormat);
Marshal.Copy(imgByte, 0, bmpData.Scan0, ImageHeight * (int)lngPitch);
bmp.UnlockBits(bmpData);
}
But it is taking too much CPU usage. I know the performance can be enhanced by using the unsafe code. Can anyone please help me or give me the code to enhance the byte array manipulation to construct a bitmap.
Any help is highly appreciated.
Thanks
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Marshal.Copy(imgByte, 0, bmpData.Scan0, ImageHeight * (int)lngPitch);
calls only a inplicit method.
[MethodImpl(MethodI
I think no performance gain with any method. Those methods already optimized.
You can find a lot of samples for pointers unsafe graphics C#.
http://www.codeproject.
All Samples, using it to implement complex graphic function (increase brightness, normalize color, ....)
You are using simple copymemory. This is already optimized for bandwith processor memory.
I think the problem arises by the size of raw bitmaps.
You can try to use original bitmaps implementation and avoid raw bitmaps.
Raw bitmaps are cached by GDI when use compressed bitmaps (jpeg, tif,...).
Resampling a bitmap to printer resolution, involves a heavy cost penalization on resources. Rs232 interface imposes a fort penalization in these situations.
I draw original bitmaps to Graphis printer, then Draw aditional information over printer area. This is fasted method.
It'is easy evaluate the memory cost of a raw bitmap. When you use Managed memory buffers, then the array is duplicated on each interop operation.
using pointers for the copy operation will not give you the improvement you are asking for.
you should think about using ParallelExtensions by Microsoft and copy the data parallel.
the download is available here:
http://blogs.msdn.com/soma
onl
there is an example called BlendImages which uses pointers in a parallel operation.
there is a similar implementation for earlier frameworks for the parallel processing:
http://www.code
Unsafe code is not inherently faster. I have done a lot of hand-tuning of C# code, and unsafe code is rarely more than 10% faster than really efficiently implemented safe code.
Memory is garbage collected in C#. That means that the memory manager can move blocks around. In unsafe code, you "pin" the memory, preventing the GC from moving the block. This adds significant pressure to the garbage collector, and only saves time if there is a lot of pinning and unpinning happening. Marshal.Copy will pin the block once, do the copy, and unpin it, so I really doubt that you will save a lot of time by using unsafe code.
The parallel suggestions are great. Keep in mind that parallel techniques are best if you want more speed (obviously), but also keep in mind that the average amount of CPU needed to do the work is significantly higher than doing it sequentially. Put simply, you might do it 3.5x faster on a quad core machine, but you will use more than 3.5x more CPU time. Also, parallel memory copies may be hampered by poor locality, causing a lot of cache misses and memory contention. You could be bottlenecked on memory bandwidth from a single thread anyway. You'd have to try it and see, and any gains may vary greatly depending on the CPU executing the code.
For interactive client apps, parallel is great. For server apps, there is higher level parallelism (multiple concurrent requests for example), so parallelizing things could cause scalability issues.
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by: Priest04Posted on 2009-10-31 at 19:37:17ID: 25712417
Have you tried using MemoryStream?
MemoryStream ms = new MemoryStream(byteArray);
Image img = Image.FromStream(ms);