.NET (Core and Framework)

15-Jul-05 4:03

I'm not sure whether the TIFF files need to handled any differently. I believe you can directly instantiate an Image object using the FromFile() method and use it howsoever you desire.

Image Binarization

sarabjs13-Jul-05 7:07

13-Jul-05 7:07

I load an image, convert it to bitmapData using the 24bppRGB pixel format, binarize it using a simple routine (shown below) and save it using the Image.Save() method. The image saved however is still 24bppRGB - although all colours have the same value, either 0 or 255 - and shows up as an RGB image in Photoshop.

Any ideas on how I can change it to binary, ie a 1bpp format?

Code:
------

Bitmap bMap=new Bitmap (iMage);
BitmapData bData = bMap.LockBits(new Rectangle(0, 0, bMap.Width, bMap.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
System.IntPtr Scan0 = bData.Scan0;
int iStride=bData.Stride;
int iht=bMap.Height;
int iwd=bMap.Width;
int iPix=new int[iht][];
unsafe
{
byte *p = (byte*)(void*)Scan0;
int nOffset = iStride-iwd*3;
for(int y=0;y<iht;++y)
{
iPix[y]=new int[iwd];
for(int x=0;x<iwd;++x)
{
if (conditionA) p[0]=p[1]=p[2]=0;
else p[0]=p[1]=p[2]=255;
p += 3;
}
p += nOffset;
}
}
bMap.UnlockBits(bData);

bMap.Save(fileName);

Re: Image Binarization

Christian Graus13-Jul-05 12:41

13-Jul-05 12:41

You need to convert it to a different format. It won't magically detect how many colours you've used and therefore change itself. There is a Clone method that takes a bit depth, but I think it's buggy. You can create a new image of the required bit depth and copy your old image onto the new. Or you could create a new image to start with of the right bit depth, and set it's values instead of setting values on your existing image.

Christian Graus - Microsoft MVP - C++

sarabjs14-Jul-05 3:55

14-Jul-05 3:55

Thanks Christian,

I found a solution from: http://www.bobpowell.net/onebit.htm

Here's what I did:

// new bitmap
Bitmap bm=new Bitmap(iwd, iht,PixelFormat.Format1bppIndexed);
BitmapData bmdn=bm.LockBits(new Rectangle(0,0,bm.Width,bm.Height),ImageLockMode.ReadWrite,PixelFormat.Format1bppIndexed);

// variables
int iIndex;
byte bP, bMask;

for(int y=0;y<iht;++y)
{
for(int x="0;x<iwd;++x)
{
iIndex=y*bmdn.Stride+(x">>3);
bP=Marshal.ReadByte(bmdn.Scan0,iIndex);
bMask=(byte)(0x80>>(x&0x7));
if (ConditionA) bP|=bMask;
else bP &=(byte)(bMask^0xff);
Marshal.WriteByte(bmdn.Scan0,iIndex,bP);
}
}
bm.UnlockBits(bmdn);

Christian Graus14-Jul-05 11:11

14-Jul-05 11:11

What is ConditionA ? This looks to me like it could be a lot slower than your old code ?

Either way, it's what I said to do - create a 1 bpp image to write to.

Christian Graus - Microsoft MVP - C++

sarabjs15-Jul-05 3:58

15-Jul-05 3:58

I have a 2-dimensional integer array of the same width and height of the image, each of whose elements is either 1 or 0. Condition A just checks whether the corresponding element in the array is a 1 or a 0, and sets the pixel accordingly

There doesn't seem to be a major drop in the time taken by the overall routine though. Do you have any suggestions?

Sarabjit.

Christian Graus17-Jul-05 12:58

17-Jul-05 12:58

If it's just an array lookup, then it probably is fine, I thought it may be missing () and be a function call that did goodness knows what.

Christian Graus - Microsoft MVP - C++

sarabjs20-Jul-05 5:07

How to change the SourcePath in a Microsoft Installer project?

20-Jul-05 5:07

Yea, it is just an array lookup...

Copying Object Types

SamM13-Jul-05 6:14

SamM

13-Jul-05 6:14

Hi
I am working on a project where I have a class containing a field of type object. I need to get a deep copy of the class, but cannot see an obvious way to copy the value of the field whos type is declared as object. I have considered using reflection to try and achieve this, but was wondering if anyone knew of a simpler way.

Any suggestions would be greatly appreciated.

Regards
Sam

Re: Copying Object Types

S. Senthil Kumar13-Jul-05 6:43

S. Senthil Kumar

13-Jul-05 6:43

Just serialize and deserialize it out of a MemoryStream. The framework takes care of the rest. Something like

using (MemoryStream s = new MemoryStream())
{
	BinaryFormatter f = new BinaryFormatter();
	f.Serialize(s, obj);
	
	s.Seek(0, SeekOrigin.Begin);
	object o = new BinaryFormatter().Deserialize(s);
	Console.WriteLine(Object.ReferenceEquals(o, obj));
}

Regards
Senthil
_____________________________
My Blog | My Articles | WinMacro

Re: Copying Object Types

SamM13-Jul-05 22:30

SamM

13-Jul-05 22:30

Thanks Senthil, great help.

Regards
Sam

bondguru12-Jul-05 20:18

bondguru

12-Jul-05 20:18

Hi all,
I am working on Microsoft Installer project to create a setup for a software. The project is already existing and working. However now I have changed the folder hierarchy i.e. I have now changed the folders from where the files to be packaged are extracted. In the project, in Properties page there is an entry SourcePath which displays the path where the file is present. This entry is still showing the old path of the files. I can't change it's contents as it is read-only. So is there any other way to change the path? If so please inform me.
Thanking You.

Regards,
Harshad

Re: How to change the SourcePath in a Microsoft Installer project?

rwestgraham13-Jul-05 15:22

rwestgraham

13-Jul-05 15:22

No. The VS.NET Setup creation IDE is very limited and poorly designed. The only way to change the source files is to delete the existing ones from the setup project and add the new ones.

Robert

Mysterious application crash

RajeshGuptha12-Jul-05 5:33

RajeshGuptha

12-Jul-05 5:33

Dear all,

My .Net WinForms Application quietly closes off without a warning and I am unable to understand the root cause of the problem, as it happens sporadically.

I am working with .Net Framework 1.1 on Windows XP (tested on both SP 1 and 2).

I tried the following:
- Having a try/catch cover on all the important event handlers (OnPaint, OnMouse..., etc) and in the static Main() method (Application.Run(...))
- Set an UnhandledException handler for the present App domain.
- Earlier, I was creating and releasing a COM object in a method that was being called many times. Now, I moved the creation into the class constructor and the releasing into the Dispose().

Yet, none of these options have either stopped the crash or have given me a clue.

Is there a way in which I can get hold of any low level API's or tools that will be able to execute my application in a shell, which will give me a greater control on locating the cause of the crash.

Any ideas will be greatly appreciated.

Thanks for reading.

-Rajesh.

Christian Graus12-Jul-05 13:34

12-Jul-05 13:34

Put a try/catch inside your static void main so you can catch the error and get a stack trace.

Christian Graus - Microsoft MVP - C++

Ray Cassick12-Jul-05 18:33

Ray Cassick

12-Jul-05 18:33

Seems to me if he was getting an unhandled exception that was causing the application to 'crash' the he would be seeing some type of exception dialog box before the app 'closes off' though.

If this can be seen under some type of controlled circumstances perhaps running the app in the debugger a while might shed some light on things. At very least he might get to 'see' it happen and maybe get some debug info that way.

When chasing things like this I usually start by gathering some statistics as to what the application was doing at the time it 'goes away' so I can get a better idea where to instrument things a bit. I then add some debug print statements and run the app with something like debugview running to get an idea as to what code was being executed last when the error happened.

George Carlin wrote:
"Don't sweat the petty things, and don't pet the sweaty things."
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If the physicists find a universal theory describing the laws of universe, I'm sure the a**hole constant will be an integral part of that theory.

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RajeshGuptha12-Jul-05 22:31

RajeshGuptha

12-Jul-05 22:31

As i said in the beginning itself that i have a try catch block in main also, but that is of no use, when it crashes. It still crashs without informing anything...

And i have tried to monitor the crashing procedure, but there is no similarity among the different occurances. I could only suspect on the Out of Memory Exception, for which i have made sure from two memory profilers that all the objects which i create, am also disposing them when they go out of scope..

I think that the problem might be at some lower level(OS level) which iam not able to get it right!!

Thanks for your suggestions.

Regards,
Rajesh

Robert Rohde13-Jul-05 4:35

Robert Rohde

13-Jul-05 4:35

Try hooking into the System.Windows.Forms.Application.ThreadException event. Other than that I have no idea Cry | :((

. Normally at least an error dialog should be displayed.