Graphics

John R. Shaw3-Mar-07 0:36

John R. Shaw

3-Mar-07 0:36

It sounds like you read a small paper of mine that was based on a piece of code (ellipses/circles/convex shapes) I wrote for doing exactly what you are talking about, but I only gave the paper to one person. Determining the number of rectangles for a circle or ellipse is not difficult [given the algorithm], provided that they consist of overlapping rectangles. Doing it for any shape gets a bit crazy and I have still not figured out that problem. The first thing you have to do (for any shape) is determine the boundaries, which means determining where each point on the edge will be drawn. Given the boundaries you must look for the all the horizontal lines that are adjacent to each other and of the same length, with the same starting and ending X values. It sounds fairly simple but it is way more complicated than that (for what I was trying to do). A good place to look is at algorithms for filling polygons like “Michael Abrash’s Graphics Programming”, He does not cover the subject you are asking about, but he does cover polygon edge scanning (polygon filling).

I am very curious as to what purpose you are applying this too and have kept my answer as general as possible, because I do not know the why.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

zbaum004-Mar-07 10:38

zbaum00

4-Mar-07 10:38

Yeah I agree for any shape (closed not open btw, but allow for holes) is a little crazy, but I think it can be done. Really the application will be filling this shape with text, but the text portion is not important to me, what is important is the rectangels that can fit in the shape. Then obvioulsy it is very easy to fill these rectangles with text.

If you have some sample code of your algorithm for convex shapes, I would love to see it.
Was it for all convex shapes or just circles and ellipses?

John R. Shaw9-Mar-07 8:35

John R. Shaw

9-Mar-07 8:35

I am afraid that I misplaced the original source code; I may have lost it, as I can only find an older version of my library. The code was originally an experiment in clipping lines to an elliptical/circle and I never generalized it for any convex shape, although I had planed too at a latter date. What I did was break the ‘Cohen-Sutherland Line-Clipping Algorithm’ (Computer Graphics Principles and Practice, Foley et al., pp. 113-117) into a series of small inline functions, so I could pick and choose the pieces required; in this case I was only interested in the corners. Given that and a list of the horizontal lines, I was able to clip all drawing done by my old graphics library to the elliptical shape as if it was a clipping rectangle. I suspect that there are faster ways to do it, but I have not thought of, nor seen, another way to do it.

If you overlay a copy of the ‘Cohen-Sutherland region outcodes’ diagram over the shape with the clipping rectangles corners touching the edges, you will see the idea behind what I was doing. Example: draw the diagram and then draw a circle around it so that the edge passes through the four corners of the clipping rectangle and you will see why I only considered the corners.

Good Luck!

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

How to Connect DV Video Encoder to FileWriter

Shog⁹9-Mar-07 11:21

Shog⁹

9-Mar-07 11:21

You might want to check out this article[^]. (Window regions are simply lists of rectangles that cover the desired area)

----

It appears that everybody is under the impression that I approve of the documentation. You probably also blame Ken Burns for supporting slavery.

--Raymond Chen on MSDN

Brooks Harris2-Mar-07 11:18

Brooks Harris

2-Mar-07 11:18

I'm attempting to write a *RAW* DV stream to a file (for other processing on it later).

In GraphEdit -
* RenderFile some (any) media file
* Delete the video renderer
* Insert DV Video Encoder and connect input pin to (some decoder's) remaining video output pin
* Insert an AVI Mux and connect to DV Video Encoder output pin
* Insert a FileWriter and connect input pin to AVI Mux video output pin

Running this results in a valid AVI file with DV media. OK, But...

This file includes the AVI wrapper header information, and this is my problem. I need ONLY the DV stream data itself, with no AVI header.

The the DV Video Encoder output pin (an XForm Out pin) will not connect directly to FileWriter input pin.

So I must understand how to convert the DV Video Encoder XForm Out stream to a form the FileWriter input pin will accept. I'm guessing I need to make a filter using CTransInPlaceFilter, but I'm not yet sure, or how to do it. Does anyone know of sample code to accomplish this?

Alternately, AVI Mux makes the correct connection, but adds the AVI header. Does anyone know of example source code for the AVI Mux Filter?

Any other suggestions welcome.

Thanks very much

Brooks

Brooks

Re: How to Connect DV Video Encoder to FileWriter

Mark Salsbery2-Mar-07 12:52

Re: How to Connect DV Video Encoder to FileWriter

2-Mar-07 12:52

The DV Encoder Filter's output pin has the following format:

Major type: MEDIATYPE_Video
Subtype: MEDIASUBTYPE_dvsd
Format type: FORMAT_VideoInfo

The File Writer Filter's input pin supports this format:

Major type: MEDIATYPE_Stream
Subtype: MEDIASUBTYPE_NULL

A transinplace filter won't work since the input and output pins must be the same.

A custom transform filter (CTransformFilter) could work though.

It may be less work to do a custom renderer filter that accepts the DV Encoder Filter's output
format and simply writes the raw DV data to a file. The "Dump" sample filter in the SDK may be a
good starting point.

"Great job, team. Head back to base for debriefing and cocktails."
(Spottswoode "Team America")

Brooks Harris3-Mar-07 3:58

Brooks Harris

3-Mar-07 3:58

Good call. That'll do it. Almost obvious, but hadn't occured to me. Thanks.

Brooks

GDI+ Region::IsVisible()

Mark Salsbery2-Mar-07 8:23

2-Mar-07 8:23

This is a repost from the MS GDI newsgroup.

Does anyone know why, in the following code, does the IsVisible() call return true?

Mark

   Rect gdiText(507, 636, 6, 7);
   Rect rctOne(512, 684, 20, 17);
   Rect rctTwo(652, 220, 47, 9);
 
   Region gdiRegion;
   gdiRegion.MakeEmpty();
 
   gdiRegion.Union(rctOne);
   gdiRegion.Union(rctTwo);
 
   gdiRegion.IsVisible(gdiText);
 
// Uncomment this code to draw the region in a window 
//   Graphics DstGraphics(*this);
//   SolidBrush blueBrush(Color(255, 0, 0, 255));
//   SolidBrush greenBrush(Color(255, 0, 255, 0));
//
//   // Draw the region 
//   DstGraphics.FillRegion(&blueBrush, &gdiRegion);
// 
//   // Draw the hit test rect 
//   gdiRegion.MakeEmpty();
//   gdiRegion.Union(gdiText);
//   DstGraphics.FillRegion(&greenBrush, &gdiRegion);

"Great job, team. Head back to base for debriefing and cocktails."
(Spottswoode "Team America")

cmk2-Mar-07 10:44

cmk

2-Mar-07 10:44

It doesn't, it returns false.
I cut/paste the above into a new project and it was fine.

...cmk

Save the whales - collect the whole set

Mark Salsbery2-Mar-07 10:49

2-Mar-07 10:49

I was afraid of that. If you get a chance can you please check your gdiplus.dll version?

It doesn't work properly for me or the OP.

Thanks much!
Mark

"Great job, team. Head back to base for debriefing and cocktails."
(Spottswoode "Team America")

cmk2-Mar-07 10:56

cmk

2-Mar-07 10:56

I'm running Win2003 R2 x64.
From VS 2005 i created a new Win32 x86 project and pasted the code in the WM_PAINT case.

My gdiplus.dll's are:
C:\WIN\WinSxS\amd64_Microsoft.Windows.GdiPlus_6595b64144ccf1df_1.0.3790.1830_x-ww_56CDF238\GdiPlus.dll File Version: 5.2.3790.1830 (srv03_sp1_rtm.050324-1447)
and,
C:\WIN\WinSxS\x86_Microsoft.Windows.GdiPlus_6595b64144ccf1df_1.0.3790.1830_x-ww_24C40C58\GdiPlus.dll File Version: 5.2.3790.1830 (srv03_sp1_rtm.050324-1447)

...cmk

Save the whales - collect the whole set

Mark Salsbery2-Mar-07 11:08

How can I find the exact colors of a grayscaled picture?

2-Mar-07 11:08

I was afraid of that too LOL

Mine is XPSP2 gdiplus.dll is 5.1.3102.2180

Where is the mythical GDI+ 1.1 ...

Thank you!
Mark

"Great job, team. Head back to base for debriefing and cocktails."
(Spottswoode "Team America")

JUNEYT1-Mar-07 9:16

JUNEYT

1-Mar-07 9:16

Hello Gentlemen!

I am working on a project in vb.net. The application will color any grayscaled picture in its actual colors. The problem is big!

All I need is an accurate advise or direction how to setup an algorithm to find the exact colors of the picture.

It seems to me that I have to find the color of each pixel first and then what? Is there any matrix about the colors what reflects a paralelism between graysacaled color set to others.

Any advise would be helpful..

Thank You! WTF | :WTF:

What a curious mind needs to discover knowledge is noting else than a pin-hole.

Re: How can I find the exact colors of a grayscaled picture?

Mark Salsbery1-Mar-07 9:28

Re: How can I find the exact colors of a grayscaled picture?

1-Mar-07 9:28

I don't think you can get exact colors from a grayscale image.

Have you searched for "colorize algorithm"?

Mark

"Great job, team. Head back to base for debriefing and cocktails."
(Spottswoode "Team America")

El Corazon1-Mar-07 10:20

Re: How can I find the exact colors of a grayscaled picture?

1-Mar-07 10:20

JUNEYT wrote:
All I need is an accurate advise or direction how to setup an algorithm to find the exact colors of the picture.

there is no way to find the "exact color" of pixel from panchromatic (greyscale). The primary issue is that panchromatic is usually luminance which follows a ration of RGB light there will usually be more than 1 color value triplet to match each pancromatic pixel.

you are trying to reverse this formula: RGB Luminance value = 0.3 R + 0.59 G + 0.11 B

so if the luminance value is say 255 (bright white luminance) what is the values of R G and B? If you know the most prominant color, a color reference, then you can figure out from the ratios the others involved.

Colorizing Panchromatic from low-resolution color reference[^]

_________________________
Asu no koto o ieba, tenjo de nezumi ga warau.
Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

Mark Salsbery1-Mar-07 11:27

Re: How can I find the exact colors of a grayscaled picture?

1-Mar-07 11:27

Damn! I wanted to read that pdf but it froze while loading Frown | :(

I'll try later. Thanks for the link!
Mark

"Great job, team. Head back to base for debriefing and cocktails."
(Spottswoode "Team America")

El Corazon1-Mar-07 11:58

Re: How can I find the exact colors of a grayscaled picture?

1-Mar-07 11:58

Mark Salsbery wrote:
Damn! I wanted to read that pdf but it froze while loading

http://www.google.com/search?hl=en&q=panchromatic+colorizing[^] there's always fun reading there. If you have my same idea of fun.

_________________________
Asu no koto o ieba, tenjo de nezumi ga warau.
Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

Mark Salsbery1-Mar-07 12:02

Re: How can I find the exact colors of a grayscaled picture?

1-Mar-07 12:02

Gracias!

"Great job, team. Head back to base for debriefing and cocktails."
(Spottswoode "Team America")

El Corazon1-Mar-07 12:04

Re: How can I find the exact colors of a grayscaled picture?

1-Mar-07 12:04

You are very welcome. Always willing to encourage the image processing addiction... you'll hate me later. Laugh | :laugh:

_________________________
Asu no koto o ieba, tenjo de nezumi ga warau.
Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

Mark Salsbery1-Mar-07 12:14

Re: How can I find the exact colors of a grayscaled picture?

1-Mar-07 12:14

It's way too late. My first computer job that's what I did.
The challenge lately has been to not get sucked into it, for the time being Smile | :)

Hopefully soon I'll have someone to do my UI programming so I can get back to the fun stuff!

"Great job, team. Head back to base for debriefing and cocktails."
(Spottswoode "Team America")

JUNEYT1-Mar-07 11:48

JUNEYT

1-Mar-07 11:48

Thanks you very much Jeffry.

I was intending to pull my sleves and jump into coding but when I examined the sophisticated algorithm behind it, I decided to roll back my sleves... Smile | :)

Thanks a lot! Smile | :)

What a curious mind needs to discover knowledge is noting else than a pin-hole.

Re: How can I find the exact colors of a grayscaled picture?

El Corazon1-Mar-07 11:55