Re: JPEG loseless and lossy compression - C# Discussion Boards

Christian Graus31-Jul-07 20:17

31-Jul-07 20:17

You really can't. You can build your header file as a managed C++ dll, and import it, that would work. However, you can't just use it in yuor project, how could you ?

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Yanshof31-Jul-07 20:29

Yanshof

31-Jul-07 20:29

In general -

What i need to do in this case ?
I can use manages C++ code - but there is some example of how i can do it ?

Christian Graus31-Jul-07 20:36

31-Jul-07 20:36

MAke your header build into a dll and set the /clr option. Then you can import this dll into your C# project.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

JPEG loseless and lossy compression

Yanshof31-Jul-07 20:40

Yanshof

31-Jul-07 20:40

ok , Thanks.

Darmi31-Jul-07 17:55

Darmi

31-Jul-07 17:55

Hi,

I want to implement JPEG loseless and lossy compression. Can anyone please help me.

Darmi

Christian Graus31-Jul-07 18:22

31-Jul-07 18:22

There are many 'JPEG' compressions. The most common one is the lossy one supported by GDI+. Creating files using this compression in C# is trivial. There are also a number of 'lossless' compressions, including JPEG 2000, JPEG lossless, etc. For JPEG 2000, I use the Atalasoft imaging library ( the J2000 stuff is an add on, and not cheap ). There are no free implimentations of J2000 that I know of, there is a JPEG lossless dll from HP, but I never actually got around to using it, I just found it in my search for a lossless compression supported by DICOM.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Darmi31-Jul-07 18:44

Darmi

31-Jul-07 18:44

Thanks Christian Graus,

But i need the implementation in C# or the algorithm to implement this compression techniques.

Thanks,
Darmi

Christian Graus31-Jul-07 18:52

31-Jul-07 18:52

I see. Well, I want a Ferrarri. Doesn't mean I can have one. Like I said, there are no C# implimentations for JPEG lossless that I know of. JPEG 2000, there are definately no free implimentations. The cheapest I found was Atalasoft, it's about $2000 plus the cost of their core library. It's very good, I use it.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Seishin#31-Jul-07 21:41

Seishin#

31-Jul-07 21:41

Image image;
...
Bitmap bmp = new Bitmap(image);

ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
ImageCodecInfo ici = null;
foreach(ImageCodecInfo codec in codecs) {
if(codec.MimeType == "image/jpeg")
ici = codec;
}
EncoderParameters ep = new EncoderParameters();
long quality = (long)100; // 0-lossy ... 100-loseless
ep.Param[0] = new EncoderParameter(Encoder.Quality, quality);

bmp.Save(fileName, ici, ep);

life is study!!!

Christian Graus31-Jul-07 22:01

31-Jul-07 22:01

No, you are totally wrong. Even at 100, a JPEG is lossy. It's just less so. And, as I said in my answer, there are many JPEG formats, including lossless ones. They are not supported by .NET, only the common lossy JPEG format is.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Seishin#31-Jul-07 23:10

Seishin#

31-Jul-07 23:10

Christian Graus wrote:
No, you are totally wrong

not totally I guess..

Christian Graus wrote:
Even at 100, a JPEG is lossy

maybe, but a lot less lossy than Image.Save()

life is study!!!

Quitting a Process Before Installing

Darmi1-Aug-07 0:03

Darmi

1-Aug-07 0:03

Hai Seishin,

I have tried this method. But i read some documents indicating two different algorithms for implementing lossy and losseless - huffman algorithm.. something like this. If we can implement lossy and loseless in the above method, then why its said that there are two different algorithms for each. Morover, i came to know that JPEG is lossy itself, but loseless have different format other than .jpg. Am i correct? Please help me.

Darmi

chaiguy133731-Jul-07 15:32

chaiguy1337

31-Jul-07 15:32

This has been bugging me for a long time. Does anyone know how to, in an MSI, quit a process before running the installation? All I want to do is quit my application so it can be properly installed over rather than give an error to the user.

Re: Quitting a Process Before Installing

Rama Krishna Vavilala31-Jul-07 17:06

Rama Krishna Vavilala

31-Jul-07 17:06

If any of the files that are in an MSI package are in use by any application, the Windows Installer automatically displays the Files In Use dialog box. This is automatically done in InstallValidate action:

http://msdn2.microsoft.com/en-us/library/aa369546.aspx[^]

Are you are not observing this behavior?

Re: Quitting a Process Before Installing

chaiguy133731-Jul-07 17:18

chaiguy1337

31-Jul-07 17:18

Oh I certainly am, however I want the installer to simply quit the running instance automatically, without prompting the user, or giving any kind of message.

There are a couple reasons I want this behavior: one being that in some cases, the installer will be launched by the application itself, as a self-update, and it seems rather dumb to have a self-updating application give an error to the user that the "file is in use". Secondly, the application is relaunched after install is complete anyway, and no information is lost by quitting.

I want the process to be seamless.

And quite frankly, I'm at a loss. What I originally thought was such a simple thing has turned out to be absurdly complicated, or at least I have yet to find a simple solution to it.

Perhaps I will investigate this InstallValidate action... is there any way to customize this behavior to run my own code at this step? Even if I could just launch another process to do the work...

change key state?

Klazen31-Jul-07 10:58

Klazen

31-Jul-07 10:58

Hey,
I am writing a program, and one of the functions of this program is to simulate holding down of two keys on the keyboard. I am not sure how to go about this. I don't think the sendkeys function is what I am looking for, because it only sends the keystroke, not holds it down. Is there any sort of way to do this?

Re: change key state?

snorkie31-Jul-07 11:38

snorkie

31-Jul-07 11:38

Have you tried searching Google? A quick search found the answer for me. Please do more research next time before posting.

Hogan

[Message Deleted]

domyansumit31-Jul-07 10:16

domyansumit

31-Jul-07 10:16

[Message Deleted]

Dan Neely31-Jul-07 10:25

Dan Neely

31-Jul-07 10:25

no because if you can't answer a question like this, you don't deserve to get a position writing really bad C# code.

--
You have to explain to them [VB coders] what you mean by "typed". their first response is likely to be something like, "Of course my code is typed. Do you think i magically project it onto the screen with the power of my mind?" --- John Simmons / outlaw programmer

Malcolm Smart1-Aug-07 8:24

Malcolm Smart

1-Aug-07 8:24

Come on dan - what was the original question? We're intrigued now...

"More functions should disregard input values and just return 12. It would make life easier." - comment posted on WTF

Pete O'Hanlon1-Aug-07 8:29

Pete O'Hanlon

1-Aug-07 8:29

He posted a sample code fragment that he'd been presented with in an interview and asked what the problems were with the class. The impression that came across was that he was in the interview at the time and had been given an internet connection. BTW - the mistakes were glaringly obvious; they weren't tricks and I would doubt the coding ability of anyone who didn't spot them. There were only a dozen lines of code after all, and he was told that there were 3 problems.

Deja View - the feeling that you've seen this post before.

Wjousts31-Jul-07 10:28

Wjousts

31-Jul-07 10:28

For starters:

It should not use a destructor to close a file stream because destruction of the object is non-deterministic. It will hold onto the open file stream until the GC decides to collect it which might not happen before the application closes. It should implement IDispose instead.