Get RAW Image from C++ Memory Pointer

[xion]

Ive got great problems solving the following problem:

Ive got some high speed camera that comes with an c++ api and SDK.
There is an OnFrameCapture callback Function that returns a
C++ pointer to the starting point of some RAW Image data stored in unmanaged Memory

Now I want to
1) Get the Image
2) convert it to jpeg
3) save it to hard disk

- I know some header data of the image like size, bits/p, pitch...
- The Pointer is returned as UInt32
- I also know the byte structure in memory (RGB24 / RGB32 / ...)

My Program is in vb.net, but I could also include some c# code...

All my tries ended up between the marshal class, API memory functions, unsafe code...

Please help me! Its urgent! (code should work on sunday )
thx in advance

 

[IngisKahn]

System.Drawing.Image does all you need. It can be created from a handle and saved in your choice of formats.

 

[xion]

System.Drawing.Image does all you need. It can be created from a handle and saved in your choice of formats.

Yes, but Drawing.Image cannot load from unmanaged memory! (would be the .fromHBitmap Function which doesnt work...

 

[HJB417]

Im assuming the pointer points to an array of bytes aka unsigned char*, determine the length of this byte array and

1) copy it using Marshal.Copy.

2) load the byte array in to a MemoryStream.

3) and using the new instance of the memory stream, invoke the method Image.FromStream.

 

[xion]

Im assuming the pointer points to an array of bytes aka unsigned char*, determine the length of this byte array and

1) copy it using Marshal.Copy.

2) load the byte array in to a MemoryStream.

3) and using the new instance of the memory stream, invoke the method Image.FromStream.

Good Idea, Ill try that!
This would work, but the data returned in the byte array is no image data... Goin to contact the manufacturer for information on that. Maybe theres some header included or the Image Size does not match

ok, Ive got to correct: This is indeed Image-Data (I can open the dumped stream with photoshop RAW import) but there is some miss-handling with the colormanagement. Maybe this is caused by the camera, that supports multiple formats like RGB32, RGB24, RGB16, RGB15, RGB8, Y8 Monochrome and so on...

So: does anybody know how to pass these color formats to image.fromstream? (it rases an error if i call the function with the memorystream only)

 

[xion]

converting RAW image byte array to image / bitmap and convert it

Now, the new Problem is to
- convert the byte array to an image (using color management information)
- convert the image to jpeg and
- save it to disk

(need a quite fast method, this should happen ~ 55 times/sec.

thx in advance

 

[HJB417]

unmanaged code = faster runtime speed
managed code = faster developtime speed
when mixing the two, you will have to use marshalling and usually this involves copying data from one runtime to another (e.x.: CRT -> CLR or vice versa).
with the exception of converting the image to a jpeg, everything should be easy to do in c/c++. There are several free image processing/converting libraries for c/c++ as Ive used a couple in the past. So my recommendation to you is to bust out some c/c++ code for faster code execution. The image class is also available in unamanged code via gdiplus.lib.

 

[xion]

unmanaged code = faster runtime speed
managed code = faster developtime speed
when mixing the two, you will have to use marshalling and usually this involves copying data from one runtime to another (e.x.: CRT -> CLR or vice versa).
with the exception of converting the image to a jpeg, everything should be easy to do in c/c++. There are several free image processing/converting libraries for c/c++ as Ive used a couple in the past. So my recommendation to you is to bust out some c/c++ code for faster code execution. The image class is also available in unamanged code via gdiplus.lib.

I would need some ready source code to implement this - cause c++ is not my favourite - so to say - and as i said, the program has to be running on sunday.
thx

 

[HJB417]

post the c# code, and what are the specs of the machine youre using?

 

[xion]

post the c# code, and what are the specs of the machine youre using?

This is the vb .net code:

vid is the activex control of the camera
vid.InquireImageMem returns current image settings
vid.GetImageMem returns the memory pointer as UInt32

Dim ptr As IntPtr
        Dim memsize, nwidth, nheight, nbits, npitch As Integer
        vid.InquireImageMem(nwidth, nheight, nbits, npitch)
        ptr = New IntPtr(Convert.ToInt32(vid.GetImageMem))
        memsize = nwidth * nheight * nbits / 8
        Dim b(memsize) As Byte
        Marshal.Copy(ptr, b, 0, memsize)
        Dim oFileStream As System.IO.FileStream
        oFileStream = New System.IO.FileStream("b" & nextfid & ".RAW", System.IO.FileMode.Create)
        oFileStream.Write(b, 0, b.Length - 1)
        oFileStream.Close()
        Dim stmBLOBData As New MemoryStream(b)
        preview.Image = Image.FromStream(stmBLOBData, False, False)
        This line rases the Error - wrong parameter
        nextfid += 1

what specs do you need?

 

[HJB417]

1) why are you using a filestream and not a memory stream? Using a memory stream will be faster.

2) I see you loading the image, but I dont see code converting it to a jpeg and saving it.

 

[xion]

1) why are you using a filestream and not a memory stream? Using a memory stream will be faster.

2) I see you loading the image, but I dont see code converting it to a jpeg and saving it.

Thank you for your help - but I found the most easy and through gdi+ also fast method:

            Dim ptr As IntPtr
            Dim memsize, nwidth, nheight, nbits, npitch, stride As Integer
            vid.InquireImageMem(nwidth, nheight, nbits, npitch)
            stride = nwidth * nbits / 8
            ptr = New IntPtr(Convert.ToInt32(vid.GetImageMem))
            Dim im As New Bitmap(nwidth, nheight, stride, get_PixelFormat, ptr)
            im.save...

Dont know why it took me so long to find this out - but searching through the web this solution is hardly mentioned...

 

[xion]

1) why are you using a filestream and not a memory stream? Using a memory stream will be faster.

2) I see you loading the image, but I dont see code converting it to a jpeg and saving it.

1) it is a memory stream, i just save the raw data into a file to debug it... like a memory dump.

2) well, i wasnt able to convert it up to now... but take the source code of my last post. this is everything I ever wanted works great at 40FPS and more... Still have to make some improvements, but alltogether it shouldnt make any problems...

Thx, guys - Wishing to help once too,
xion