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You need to either use GetPixel ( which is slow ), or make your image a DIBSection or use GDI+ to access the bits as an array.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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Thank you for your reply, could you give me some idea on it?
I have no idea.. 
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In what format is the frame stored?
Assuming you used ISampleGrabber you will have a frame stored
in whatever format the video pin directly upstream of your
sample grabber is configured to. e.g 24-bit YUV ( FourCC, IYUV )
This is essentially an array of YUV values so first you will
want to access the YUV values (3 bytes) at the pixel location
Use a BYTE pointer that is set to a function of your frame
buffer start, buffer width, Pixel X and Y position and size (in bytes)
e.g. assuming 640 x 480 24-bit YUV (3 bytes), To find pixel(X,Y) :
BYTE *pPixel = pBufferStart + ( Y * 640 * 3 ) + ( X * 3 );
Now
BYTE Y = *pPixel;
BYTE U = *(pPixel+1);
BYTE V = *(pPixel+2);
This will be different if the stored frame is in another format.
Assuming you correctly get the pixel YUV values now convert
to RGB
Of the top of my head I think the formula is :
R = 1.164*Y + 1.596*V;
G = 1.164*Y - 0.813*V - 0.392*U;
B = 1.164*Y + 2.017*U
But I'm not sure. You can look it up.
In ant case if you're doing a lot of pixel testing you
should build look-up tables from those formulas at
initialization time.
Steve T
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Thanks for your reply!
another question, how can I store the frame to buffer from the USB camera, and how to compare two frames if they are different?
Thanks alot!
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Thanks for your reply!
another question, how can I store the frame to buffer from the USB camera, and how to compare two frames if they are different?
I use ISampleGrabber in a DirectShow filtergraph to get video frames
(there are other ways)
Here is the DS documentation: ISampleGrabber
There is some sample code if you click through "Using the Sample Grabber"
As to comparing two frames: what differences do you want to detect
and how sensitive to change do you want your detection to be?
In a live video stream even visually indistinguishable frames will have
at least some minor diffences due to tiny camera vibrations, subtle
changes in light-level, sensor "noise", etc.
One simple test you can do on a per-pixel basis is simply compare
the Y-values of corresponding pixels in two frames (in YUV format).
This essentially monitors for a change in brightness. (Like comparing
two gray-scale pixels)* If you are more interested in looking for
changes in a particular area of your frame you could accumulate
Y-values in that area of each frame (add the Y values for each pixel
in the area, average them or accumulate each pixel's difference--whatever
is appropriate for your application--then compare the accumulation
to see if passes a threshold, indicating the selected area of your
video frame has changed.
*If instead of converting a YUV image to RGB using the formula
I gave you simply use the Y value for R, G & B you will get a
gray-scale image.
Steve T
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I want to create and write a DICOM file (include one or more image) in C but i don't know how to begin. Can you show me, please
Sincerely
Thangnvhl
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You need to buy or find an SDK for reading DICOM files. There are some free ones about, but others cost in the vicinity of $5k, so I expect the free ones are not exactly complete.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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Thanks for your reply. Could you show me where i can buy or find these SDKs?
Sincerely
Thangnvhl
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If you can't use google, the SDK's will be of no use to you when you buy them.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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Hi, i am a newbie, and i am trying to implement a control array as its called in VB, in VC. I have put the following code in a dialog's OnInitDialog() method:
pButton[0] = new CButton;
pButton[0]->Create(_T("My button1"), WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON, CRect(10,10,100,30), this, 1);
pButton[0]->ShowWindow(SW_SHOW);
pButton[1] = new CButton;
pButton[1]->Create(_T("My button2"), WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON, CRect(110,10,200,30), this, 2);
pButton[1]->ShowWindow(SW_SHOW);
But i dont know how to catch their events. Actually, i want to create a dialog which on the basis of a number creates that many buttons. I can read the text of that button and know which button it is. but first i have to catch the event. Please if any of u have any alternatives to this do tell me.
and which library do u prefere for such tasks MFC, ATL or ... (i m not sure about).
To hit 3rd floors window you have to AIM for 5th or Higher.
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you can doit inside OnCommand by filtering the controls by the id
in this case 1 or 2
...100,30), this, 1);
something like this
BOOL CYourClass::OnCommand(WPARAM wParam, LPARAM lParam) <br />
{<br />
switch(LOWORD(wParam)) <br />
{<br />
case 1:<br />
DoSomething1(); <br />
break;<br />
case 2:<br />
DoSomething2();<br />
}<br />
}
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Well, im using MFC and the situation is something like this:
class CExperimentButtonsDlg : public CDialog
{
...
protected:
HICON m_hIcon;
CButton* pButton[2];
}
BOOL CExperimentButtonsDlg::OnInitDialog()
{
. . .
CDialog::OnInitDialog();pButton[0] = new CButton;
pButton[0]->Create(_T("My button1"), WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON, CRect(10,10,100,30), this, 1);
pButton[0]->ShowWindow(SW_SHOW);
. . .
}
So u know the windowproc is not in my control, its in MFC's. Now, what would be the solution.
To hit 3rd floors window you have to AIM for 5th or Higher.
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you could overwrite the CButton and manage its callback manually ...
but you will still need some kind of ID with each button ...
for example in pseudo-pseudo-code
pButton[0]->Create( this, eButton1 ); // eButton1 is a enum
pButton[1]->Create( this, eButton2 ); // eButton2 is a enum
pButton[2]->Create( this, eButton3 ); // eButton3 is a enum
pButton[3]->Create( this, eButton4 ); // eButton4 is a enum
and in your button class, you could do something like
void MyInheritedButton::Create( CWnd* pParent, enum eButtonID )
{
m_pParent = pParent;
m_eButtonID = eButtonID;
}
void MyInheritedButton::OnButtonClick()
{
m_pParent->SendMessage( eButtonID );
}
and in the parent ( or whereever you can catch the message ) you just do whatever you do on each button depending on the enum.
Maximilien Lincourt
Your Head A Splode - Strong Bad
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you can use the soluction i gave you.
BOOL CExperimentButtonsDlg::OnCommand()
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one easy way whereby which u can do thiz is by deriving ur own class from the CButton Class and adding in the eventz(messages) u need by using the classwizard.....
eitheR way i think then itz best u make ur own buTton class from the scratch with CStatic.....
Happy programmin.....
cheerz.....
"faith, hope, love remain, these three.....; but the greatest of these is love" -1 Corinthians 13:13
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I think there is an easier solution instead of subclassing your own control.
If I understood well your question, you want to display X (which is only known at runtime) buttons on a dialog and create them dynamically on initialisation of your dialog. Then, when a specific button is pressed, you want to call a function.
The first thing you made is correct: this way you create dynamically the button and place it where you want. The only thing that is not really clean is that you give your own Id's. These Id's may already been used for other controls so it's not a good idea. What you need to do is reserve a range of id's in the resources.h file, something like:
#define IDC_BUTTON1 32000<br />
#define IDC_BUTTON100 32100
Then when creating your buttons:
for (int i=0;i<iNumButtons;i++)<br />
{<br />
pButton[i] = new CButton;<br />
pButton[i]->Create(_T("My button1"), WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON, CRect(10,10,100,30), this, IDC_BUTTON1+i);<br />
pButton[i]->ShowWindow(SW_SHOW);<br />
}<br />
Of course, in the loop you'll need to change the rectangle of the button and the title...
Now, to associate a function with each of these buttons, you can make use of the ON_COMMAND_RANGE macro (in the message map):
ON_COMMAND_RANGE(IDC_BUTTON1,IDC_BUTTON100,OnButtonRange)
Take a look at the documentation to have a complete help on this macro and how to use it.
Hope this helps
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You all guyz, thank you for u responses. But cedric moonen, got my point 120% right. and his solution is exactly what i needed. I was going through the Wrox "Professional MFC programming with Visual C++", and there the writer took me through the disection of the Different macros used by MFC to declare the Message Maps. they are defined in Afxwin.h.
As suggested by him, too,
ON_COMMAND_RANGE(IDC_BUTTON1, IDC_BUTTON100, OnButtonRange)
will work just fine.
Since i got some inside information from my research, i would like to share it with you guyz. Actually there is a structure for each message handler entry in the message map which is hidden from the programmers. MFC maintains an array of this structure in every class where you use
BEGIN_MESSAGE_MAP( class, baseClass)
That entry structure is something like this:
struct THESTRUCT
{
UINT nMessage;
UINT nID;
UINT nLastID;
UINT nSig;
pointerToFunctionHandler;
};
nMessage is, of course, the message to handle.
nID is, of course, of course, the of target control (for which the message is intended)
nLastID, this is the essence. If you want one function to handle multiple controls having their IDs with in a specific range. Then nID is the Lowest ID inclusive and nLastID is the highest ID.
nSig is a long value that specifies the function Signature of the handler function.
Hope this is helpful.
and Thanks, you've all been very useful. ![Rose | [Rose]](https://codeproject.freetls.fastly.net/script/Forums/Images/rose.gif)
To hit 3rd floors window you have to AIM for 5th or Higher.
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I'm working on an email app and would like to add an "auto-fill" style functionality as they address a message.
I have an edit box where they can enter the addresses. If they hit PageDown while addressing, then a small dialog appears with a listctrl that displays all the address book aliases that match the portion of the address they have typed.
(See http://www.specialtysound.com/autofill.jpg for a screen shot)
Here's the problem: I would like the dialog to disappear if they click anywhere outside of it.
I'm creating a standard dialog with the following styles:
WS_POPUP, WS_VISIBLE, WS_CLIPSIBLINGS, WS_BORDER, WS_OVERLAPPED, DS_3DLOOK, DS_SETFONT and WS_EX_LEFT, WS_EX_LTRREADING, WS_EX_RIGHTSCROLLBAR, WS_EX_TOOLWINDOW, WS_EX_CONTROLPARENT
I instantiate the class and call DoModal().
Any help would be great. Thanks!
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Hi,
How to add CString member variable to mfc application. FYI, I am building mfc application using visual studio .net.
Thanks
Vinay
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Oh, man.
I suggest buying a book like 'teach youself C++ in 24 hours', or 'C++ for dummies'. For every thing like this you get answered on a forum, there will be 5 things you never think to ask, and you need to know.
In your header file, put the member variable declaration. If you look up from where you put it, the last one of these: public:, private:, protected:, will define the scope of the variable. Now you can use it within the class.
It's best to make your members private first, then expand the scope if you need to. It's also best not to make member variables public, that exposes implimentation details. Provide get and ( if warranted ) set methods instead.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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I know enogh c++ but do not know the ever changing development environment under different conditions.
I think, just by looking at the subject of my posting, readers who are looking for great/advanced questions, can skip  .
comign to the actual problem.....
If I want to add a member variable in VC++ 6.0, I used to do following.
1.Select the class(in class view)
2.right click
3.choose add member variable
4.enter variable name and variable type. I can enter any type of variable because variable type is an edit box.
But in VC++ 7.0(visual studio .net), variable type is a list box which allows to choose inegral type of variables. So how to choose CString.
I entered CString manually in header file. But CString variable was taken from atl library but I want it to be taken from MFC libraries.
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Both ways that you describe are useful only if you want to be clueless forever. The more you rely on the IDE for such simple tasks, the longer it will take for you to ever have any idea how to program, or how things are working in your chosen language/framework. I've never used that stuff, in VC6 or VC7. I'll put variables where I want them, how I want them.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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Do you think, I always use wizard to add a variable?
Wizards add code to the project and sometimes user does not know where the code was written.
But when a variable is added to project using wizard, does the programmer does not know where it was added? hhhaa
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vchedalla wrote:
Do you think, I always use wizard to add a variable?
I dunno, you're telling the story.
vchedalla wrote:
But when a variable is added to project using wizard, does the programmer does not know where it was added? hhhaa
It's not as hard to find as when you use a wizard to add a COM method, but the principle is the same - someone who uses wizards all the time is unlikely to really understand what's going on. Besides, if you don't use them, why the question ?
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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