Graphics Discussion Boards

vdtwo30-Sep-08 0:24

30-Sep-08 0:24

Has anyone have any resources (articles, algorithms, code etc) about how to flatten a hand-drawn line. I'll really appreciate it.

Re: Flattening a drawn line

Alan Balkany30-Sep-08 4:26

Alan Balkany

30-Sep-08 4:26

The Hough Transform is good for that. It can identify the position and slope of a line, even with errors in the data.

It considers each dark pixel as evidence the line passes through that point. As it process each dark pixel in the hand-drawn line, it accumulates evidence for all possible lines. The line with the most evidence is selected as the result.

(The Hough Transform can also recognize a lot more than just lines.)

A different (and simpler) approach is to use linear regression to get an equation of the line that best fits the points.

Re: Flattening a drawn line

Alan Balkany30-Sep-08 4:28

Alan Balkany

30-Sep-08 4:28

Another quick-n-dirty approach: Take the first and last point of the hand-drawn line, and find the equation of the line connecting them. Probably the simplest approach, which may be good enough for your purposes.

Re: Flattening a drawn line

vdtwo30-Sep-08 6:39

vdtwo

30-Sep-08 6:39

Thanks for the answer, I heard about the hough transform but never thought it could be the solution. Btw do you know any sample applications (or articles etc) that uses the hough transfrom for similar purposes, so I can examine it...

Re: Flattening a drawn line

Alan Balkany30-Sep-08 6:41

Alan Balkany

30-Sep-08 6:41

http://en.wikipedia.org/wiki/Hough_transform[^]

GDI+ and DPX file format

Sonhospa29-Sep-08 5:14

Sonhospa

29-Sep-08 5:14

Hello gurus Smile | :)

trying to work on a bitmap I trapped into possible GDI+ limitations. In the help I find only a few formats that GDI+ supports (standards like BMP, JPG etc.) but not the format I need: DPX.

Is there any way to expand the possibilities and capture a DPX bitmap? I know there are some programs that can handle the format under windows, so I can't imagine there wouldn't be an elegant way... D'Oh! | :doh:

Thanks in advance
Michael

Re: GDI+ and DPX file format

Alan Balkany29-Sep-08 7:11

Alan Balkany

29-Sep-08 7:11

If you only need a fixed number of DPX bitmaps, you can display them in whatever DPX viewer you have, select the image (left click), press Alt-PrtScn to copy the image to the clipboard, paste the image into MS Paint, then save the image as a bitmap file.

Re: GDI+ and DPX file format

Sonhospa29-Sep-08 7:48

Sonhospa

29-Sep-08 7:48

Unfortunately it's more often Smile | :)

and I'll have to make an application which collects the relevant files and repairs them automatically.

If it's really not possible in VB Express direct, I guess I'm going to call GraphicsMagick (which btw does a great job in graphics transformations with almost every imaginable format) to repair image after image. Still I'd have loved to do it directly within the app... Cry | :((

Thank you anyway!

AVI Duration

dwg198629-Sep-08 0:50

dwg1986

29-Sep-08 0:50

Hi,

I'm trying to retrieve the duration of an AVI file using Microsoft.DirectX.AudioVideoPlayback.Video class. This used to work on my previous XP machine, but on my new Vista machine its throwing a DirectXException

"Error in the application";
ErrorCode: -2147467262
ErrorString: "E_NOINTERFACE"

This exception is being thrown if I call the Video.FromFile method. Please help..

Thanks in advance,

Daniel

Re: AVI Duration

Tim Craig29-Sep-08 9:55

Tim Craig

29-Sep-08 9:55

Do you know which technology that class uses under the covers? If it's VFW, that's not supported on Vista. Broke a bunch of OpenCV apps, too.

If you don't have the data, you're just another a**hole with an opinion.

Re: AVI Duration

Mark Salsbery29-Sep-08 10:24

Mark Salsbery

29-Sep-08 10:24

You may need to install the latest DirectX runtime[^].

I'm not sure the managed DirectX stuff comes with Vista.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AVI Duration

dwg198630-Sep-08 0:50

dwg1986

30-Sep-08 0:50

Without installing anything, references to the Managed DirectX libraries are available in VS2008 on Vista. I then installed the latest DIrectX SDK, but nothing changed.

No, I dont think its underlying technology is VFW. As far as I know, that evolved into DirectShow.

Is there any other way, which as easy as using the DirectX managed libraries to get the duration of an AVI file? Any harder solutions are also welcome ...

Thanks for your replies.

Daniel

Re: AVI Duration

Mark Salsbery30-Sep-08 4:54

Mark Salsbery

30-Sep-08 4:54

AFAIK, managed DirectX isn't supported anymore but it is still
included as "extras" with the redistributable end-user run time.

If you can post the code that fails (it's just one missing interface, right?)
I will test it on the latest DirectX extras on Vista.

dwg1986 wrote:
I dont think its underlying technology is VFW

No, it's not. DirectShow works with WDM drivers and can work with
legacy VFW devices.

dwg1986 wrote:
Is there any other way

You can always parse the AVI info yourself... AVI RIFF File Reference[^]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AVI Duration

dwg198630-Sep-08 7:13

dwg1986

30-Sep-08 7:13

Thanks for your reply. The code fails at runtime in the underlined line of code below:

using System;
using System;
using System.Windows.Forms;
using Microsoft.DirectX;
using Microsoft.DirectX.AudioVideoPlayback;

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Test()
        {
            double dDuration = 0;
            try
            {
                Video video = Video.FromFile("C:\\Test.avi");

                dDuration = (video.Duration / 60);
            }
            catch (DirectXException dxEx)
            {
                MessageBox.Show(dxEx.Message);
            }
        }
    }

The underlined line of code is where the DirectXException described in my original question is thrown.

Thanks again,

Daniel

Re: AVI Duration

Mark Salsbery30-Sep-08 9:26

Mark Salsbery

30-Sep-08 9:26

I can confirm the error.

I can't confirm that Managed DirectX is supported on Vista.

It's not included in the latest DirectX SDK or the latest Platform SDK.

Do you have any links to info stating it's still supported?

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AVI Duration

Mark Salsbery30-Sep-08 9:43

Mark Salsbery

30-Sep-08 9:43

Just for the heck of it, I tried the code on a WMV file...

It worked fine.

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AVI Duration

dwg198630-Sep-08 10:08

dwg1986

30-Sep-08 10:08

Wow, true.. it worked on a WMV. Confused | :confused:

I found a link which might hint some Managed DirectX issues on Vista: http://www.thezbuffer.com/articles/470.aspx[^], and other sites also hinted similar incompatbilities due to DirectX 10.

There is also mention of MDX.. but I have not yet a clue what it is exactly.

Still its strange it works on a WMV and not on an AVI.

Re: AVI Duration

Mark Salsbery30-Sep-08 16:12

Mark Salsbery

30-Sep-08 16:12

I saw that link too. Not much mentioned about it during the
last year or two.

dwg1986 wrote:
MDX.. but I have not yet a clue what it is exactly.

MDX == Managed DirectX I suppose Smile | :)

dwg1986 wrote:
Still its strange it works on a WMV and not on an AVI.

Yeah - I wish I had the source code to see what the Video
class is using and what's missing on Vista!

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AVI Duration

dwg19861-Oct-08 7:42

dwg1986

1-Oct-08 7:42

Oh yeah.. MDX, Managed DirectX. *slaps himself* Damn was I tired.

So my options till now are:

1. Convert AVI library to WMV. No sense there.
2. Resort to some other third party SDK. (which I still have not found after hours searching)
3. No idea.

I'll post back if I get any success.

Thanks for all your help.

Re: AVI Duration

Mark Salsbery1-Oct-08 8:13

Mark Salsbery

1-Oct-08 8:13

If all you need is duration, you could use the old
Video for Windows (VFW)[^] APIs via platform invoke:

Opening Streams in an AVI File and Closing the File[^]
A Simple C# Wrapper for the AviFile Library[^]

If you're doing more complicated things with th AVI files you
could use DirectShow[^] via COM or p/invoke.

I also saw references to a managed directx wrapper on Sourceforge that
supposedly is better than Microsofts old managed directx offering:

DirectShow.NET[^]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

GDI+ how can I add transparent to image that doesn''t had one? [modified]

xanagan66626-Sep-08 1:07

xanagan666

26-Sep-08 1:07

My Project required that I have to load the image from resource.
using Gdiplus::Bitmap::FromResource function , so I have to save the image in BMP format and it doesn't support alpha channel.

Are there anyway I can access the internal data of image after loading it so I can add alpha=0 to pixel that has particular color?

something like this psuedo code

for(int i=0;i<totalpixel;i++){>
if(pixel[i].r == pixel[i].g == pixel[i].b == 0){//if the pixel is black
pixel[i].a = 0;
}
}

thank in advance

modified on Friday, September 26, 2008 7:27 AM

Re: GDI+ how can I add transparent to image that doesn''t had one?

Mark Salsbery27-Sep-08 9:28

Mark Salsbery

27-Sep-08 9:28

Load the bitmap

Create a new Bitmap object with pixel format PixelFormat32bppARGB

Create a Graphics object from the new bitmap

Draw the original bitmap on the Graphics object

Use Bitmap::LockBits on the new bitmap to get direct access to the
pixel bits (the BitmapData struct has all the info you need to iterate
through the pixels)

Loop through the pixels setting alpha channel values as desired

Call Bitmap::UnlockBits on the new Bitmap

Dispose the Graphics object and the original bitmap

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: GDI+ how can I add transparent to image that doesn''t had one?

xanagan66628-Sep-08 15:03

xanagan666

28-Sep-08 15:03

Thank for your answer , I will try it

The same in VB?

Sonhospa29-Sep-08 6:12

Sonhospa

29-Sep-08 6:12

Is there also a way to loop through the pixels in VB?

Thank you
Michael

screencapture partly black

jVersteegen25-Sep-08 1:50

jVersteegen

25-Sep-08 1:50

hello
tried to make a screencapture of a panel with controls on it and "connections" at the background (created using paint() procedure). DrawToBitmap does only the visible part of the panel, so i came up with the following code after a while. problem is that the invisible part of the panel turns up black in the resulting jpeg picture. Does anyone have any suggestions for me?

public static void CreateScreenCaptureFile(Control ctrl, string path)
{
// get dimensions (part may be invisible)
int w = 0,h = 0;
foreach(Control c in ctrl.Controls )
{
if(c.Left + c.Width > w) w = c.Left + c.Width + 100;
if(c.Top + c.Height > h) h = c.Top + c.Height + 100;
}
if(w == 0) w = ctrl.DisplayRectangle.Width;
if(h == 0) h = ctrl.DisplayRectangle.Height;

// create bitmap
IntPtr hwnd = ctrl.Handle;
Bitmap b = new Bitmap (w, h);
Graphics bg = Graphics.FromImage (b);
IntPtr bgdc = bg.GetHdc ();

SendMessage(hwnd , WM_PAINT, (int)bgdc, 0);
SendMessage(hwnd, WM_PRINT, (int)bgdc, (int)(
DrawingOptions.PRF_OWNED |
DrawingOptions.PRF_CHILDREN |
DrawingOptions.PRF_CLIENT)
);

bg.ReleaseHdc();
bg.Dispose ();

// save the result jpeg file
b.Save(path, ImageFormat.Jpeg);
b.Dispose ();

}

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