Re: Saving image as JPEG - best possible quality - C# Discussion Boards

Re: watching process and the data they access

9-Jun-04 15:42

It's possible to do, but hardly practical. You will need to write a file system driver that attaches filter objects to the O/S device objects. This driver can then expose an interface that your main application can use to get the information it wants.

You'll need to know about writing Windows NT kernel drivers, internal workings of Windows NT kernels, and, of course, the internals of NTFS.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

tjawed9-Jun-04 18:31

tjawed

9-Jun-04 18:31

wowww - and i thought it would be pretty straightforward. thanks for giving me an idea of how complicated it would be.

thanks

Saving image as JPEG - best possible quality

michalJ9-Jun-04 11:44

michalJ

9-Jun-04 11:44

Is there any possibility to save Bitmap as JPG, however
with better quality than allows the following code :

...
encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality,100);

foreach( ImageCodecInfo encoder in encoders ) //PERF OPT
{
if( encoder.MimeType == "image/jpeg" )
{
img.Save(stream,encoder,encoderParameters);
}
}

When saving images with maximum possible quality I get files that
are about 80% of size of image produced by Adobe Phooshop,
even with 10 (scale 1-12 ) quality (!)
It was somewhat about 160 kB, versus 200 kB, and of course,
the difference had been evident. The difference was visible
due to the fact that on the original image some lines and polygons
along with text were drawn. And these require quite a good
compression quality.

Sombody might say that I should save images as GIF or PNG, however
these do not provide as good compression ratio as JPEG does, even
when saving JPEG with the best quality (size increases)
(best JPEG by PhotoShop == 320 KB, best by framework == 160 KB,
PNG = 770 KB)

When saving image as JPEG with photoshop, user is able to choose
compression level (that seems to be "wider" than what framewotk
provides) and is able to choose from "Format options" that are
following: BaseLine, Baseline-Optimized and Progressive.
Is there any way to make the same work in GDI+ ?

But the main question remains : How to save image with quality
better than that from the above code example.

Thanks
Michał Januszczyk

Dave Kreskowiak9-Jun-04 12:07

9-Jun-04 12:07

The problem is the JPEG "compression". You don't get good compression with high quality. The JPEG format is well-known to not handle lines polygons with good quality. JPEG is for photographic type images where the "lossyness" can be hidden in the image. Your just not going to get high quality images without sacrificing compression with JPEG.

For the type of image that your talking about (lines and polygons) .GIF is a much better choice. But, it also has it's limitations, like limited color depth support.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

michalJ9-Jun-04 12:13

michalJ

9-Jun-04 12:13

Dave Kreskowiak wrote:
The problem is the JPEG "compression". You don't get good compression with high quality. The JPEG format is well-known to not handle lines polygons with good quality

Thank You.

Yes, i'm aware that JPEG will not do as good image as GIF would do here , but I would like simply to get as much as Photoshop gives, and this would sattisfy me really.

Let me say that again: I draw lines on background that is a photo. Savig whole image as GIF of PNG would produce enormously big image size, and savig as JPEG does not (currently) give appropriate quality. However Photoshop _is_ able to save as JPEG, with quality even beter than ramework does, and this quality is in my opinion good enough to save lines drawn on photo-background.

Michal

Heath Stewart10-Jun-04 3:18

Heath Stewart

10-Jun-04 3:18

But as Dave said, so long as you compress a JPEG using most compression algorithms (which are lossy), you will loose quality. My recommendation is - much like you did for the quality encoder parameter - adjust the compression algorithm as well until you find a happy medium. Perhaps find out which compressional algorithm Photoshop is using (LZH, IIRC) and use the same.

Also keep in mind other properties Photoshop may be saving. Just looking at the file sizes may not be enough. By default, Photoshop will save ICC profiles with images and may embed other properties when possible (using EXIF with JPEG, it is possible). Unless the image sizes are large, an 80% margin isn't completely unbelievable (though it sure pushes it).

Microsoft MVP, Visual C#
My Articles

michalJ11-Jun-04 2:45

michalJ

11-Jun-04 2:45

Heath Stewart wrote:
My recommendation is - much like you did for the quality encoder parameter - adjust the compression algorithm as well until you find a happy medium. Perhaps find out which compressional algorithm Photoshop is using (LZH, IIRC) and use the same

I've investigated the matter, and it seems that whan saving image as JPEG, the only encoder paarameters that can be used are: Transformation and Quality. (As I noted before Quality when set even to maximum does not suit my needs). Compression encoder parameter is available only whan savig image as TIFF (available options are: none, LZW, Rle, CCIIT3, CCIIT4)

Thanks
Michał
Cry | :((

sockets

surgeproof9-Jun-04 10:30

9-Jun-04 10:30

does anybody have a link to a tutorial that is tried and tested and simple and accurate and etc. :P on how to use sockets in c#?

what i need to do is to connect to a specific ip on a certain port, send info and recieve and process it, then send more depending on what's been sent etc.

what type of connect is also best to use?

thanks.

-------------------------------------------------------
ithium is the best.

'Science without religion is lame, religion without science is blind.' --Albert Einstein
'The pioneers of a warless world are the youth who refuse military service.' --Albert Einstein

Heath Stewart9-Jun-04 10:48

Heath Stewart

9-Jun-04 10:48

There are several good ones here - use the ratings to see what people think is good.

As far as the protocol, that is defined entirely by you. Sockets are a simple connection between, well, sockets. That's it. More than likely, you'll want to use a TcpClient if you want to use TCP/IP for the connection protocol. What comes across the wire is defined by you, however.

Tons of protocols including HTTP, SMTP, FTP, etc. all use TCP/IP, but the protocol - the messages sent back and forth - is unique to each (though some common approaches exist, such as headers vs. body). In fact, someone earlier today simply asked about "telnet". Telnet is really just a simple TCP socket connection with know particular protocol.

A good way to handle this is to connect using a TcpClient and getting a NetworkStream by calling TcpClient.GetStream. Instantiate a StreamWriter and StreamReader on that stream with an agreed-upon encoding (like ASCII, UTF8, Unicode, etc.). Send and receive commands.

A good protocol will define errors codes that typically prefix a response message, making it quick and simple for you to determine if a command passed or failed.

For good examples of such protocols, I recommend you search http://www.ietf.org/rfc[^] for RFCs describing TCP protocols like SMTP, HTTP (pretty easy one), FTP, etc. I would recommend DICT (http://www.ietf.org/rfc/rfc2229.txt[^]), which I'm currently wrapping (slowly, with low priority). It's a simple protocol and gives you a pretty good idea of a good protocol design.

Microsoft MVP, Visual C#
My Articles

GISnet9-Jun-04 10:51

GISnet

9-Jun-04 10:51

This article http://www.codeproject.com/csharp/pop3client.asp[^] will help a lot because it is simple, uses sockets to send and receive data with a pop3 server (which is cleartext)... exactly what you want.

The best part is, if you're just doing this to learn, you dont need to write the server piece!

Microsoft .NET - Come on! I need the Traffic!

eggie59-Jun-04 19:05

eggie5

9-Jun-04 19:05

make a little pop3 class to talk to your email server and read your messages etc. You coul make a class for all the pop commands like AUTH, LIST etc. Read the pop3 rfc, its very simple. I did something like this, and it was a fun way to learn .net sockets...

/\ |_ E X E GG

surgeproof10-Jun-04 5:27

10-Jun-04 5:27

thanks all. Smile | :)

-------------------------------------------------------
ithium is the best.

'Science without religion is lame, religion without science is blind.' --Albert Einstein
'The pioneers of a warless world are the youth who refuse military service.' --Albert Einstein

serial port

surgeproof9-Jun-04 10:29

9-Jun-04 10:29

hi - is there a simple and good way to control the 9-pin serial port at the back of your computer? i would like to use it for some simple electronics commands and i need to be able to send a certain number of pules to it over a set time,- also how can you recieve?

i found this link on google, is it right? and what is i don't want to send a message to want to pulse it? any ideas? Smile | :)

cheers,
surgeproof

-------------------------------------------------------
ithium is the best.

'Science without religion is lame, religion without science is blind.' --Albert Einstein
'The pioneers of a warless world are the youth who refuse military service.' --Albert Einstein

Re: serial port

Dave Kreskowiak9-Jun-04 11:59

9-Jun-04 11:59

Simple? Not on your life...

You said your looking to send signal pulses? The article you found won't let you do that. That article deals with properly formatted serial communications. You're apparently looking at manipulating the serial port hardware directly and in very non-standard methods. Your going to have a DIFFICULT time with this one. Receiving data is going to be very difficult at best.

You might have better luck with using the parallel port for a project like this. Most of the same problems apply, but there is more documentation on this port than with serial. For example...[^]

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

Re: serial port

quilkin10-Jun-04 5:21

quilkin

10-Jun-04 5:21

I agree with Dave, what you're trying to do is pretty impossible.
Better to get hold of a development kit for a simple microcontroller (e.g. a Arizona Micro PIC device) that has an on-baord UART and talk to that via your PC serial port. The PIC can be programmed to generate your pulses, etc, depending on the instructions it gets via the serial port.

Re: serial port

surgeproof10-Jun-04 5:29

MDI Child focus problem when button is disabled

10-Jun-04 5:29

cheers both for your helpful responses. i will soon be getting more into PIC development, and i have a PIC programmer coming soon, so i may be able to figure out UART if i need it. Smile | :)

thanks for now,
surgeproof.

-------------------------------------------------------
ithium is the best.

'Science without religion is lame, religion without science is blind.' --Albert Einstein
'The pioneers of a warless world are the youth who refuse military service.' --Albert Einstein

Unhandled Exceptions

Flack9-Jun-04 9:54

Flack

9-Jun-04 9:54

Hello,

If I want to manage all unhandled exceptions myself, do I have to subscribe to both the AppDomain.CurrentDomain.UnhandledException and Application.ThreadException events or would it be enough to just subscribe to the Application.ThreadException event?

Does the Application.ThreadException event handle all unhandled exceptions or does the UnhandledException event of the CurrentDomain handle some?

Thanx for the clarification Big Grin | :-D

-Flack

Re: Unhandled Exceptions

Heath Stewart9-Jun-04 10:35

Heath Stewart

9-Jun-04 10:35

They both allow you to handle unhandled exceptions, but handling the Application.ThreadException gives you a good chance to make sure your application remains stable. Unhandled exceptions that affect the message pump are potentially dangerous. For example, unhandled exceptions in certain places (like when a form is loading) will cause the 'X' button in your window to stop responding, along with others errors you might not notice right away.

Of course, if you're not using Windows Forms (say, a Console application) then handle the AppDomain.UnhandledException event.

Microsoft MVP, Visual C#
My Articles

rlacatus9-Jun-04 9:13

rlacatus

9-Jun-04 9:13

Hello,

I cannot figure out where this problem comes from, so I'm looking for suggestions. In my windows app I have multiple MDIs open as well as a panel on the MDI Parent. This panel contains buttons that get disabled ( btn01.Enable = false; ) programmatically when another button is clicked.

I can reproduce this every time:

1. The buttons and labels on this "parent" panel are enabled and populated respectively from the OnMDIChildActivate() event.
2. When a button is clicked, another button is disabled. Due to that last event the active MDI child changes to the first one opened rather than to continue with the code in the function being processed (the onClick event handler).

Note: There is no event handler for the "disable button" event.
Note: The OnMDIChildActivate() event takes a DataSet from the MDI Child which it uses to populate the panel.

Any suggestions?

Thanks,

Remus

Re: MDI Child focus problem when button is disabled

link_799-Jun-04 9:26

link_79

9-Jun-04 9:26

Hi,

A couple fo questions -
+ Is the button that is being disabled on the active form or another form?
+ Also you say the code jumps out of the OnClick handler, did you mean focus only but code executes fine.

You might have to take the long way - write a diable event that returns focus to the 'current' mdi form window.

Re: MDI Child focus problem when button is disabled

rlacatus9-Jun-04 11:19

rlacatus

9-Jun-04 11:19

Hello,

"+ Is the button that is being disabled on the active form or another form?"
A: The button is found on the same panel in the MDIParent as the button that is being clicked when it is disabled.

"+ Also you say the code jumps out of the onclick handler, did you mean focus only but code executes fine."
A: The code after the ( Button.Enable = false; ) line is not executed - I found out through MessageBox.Show() that it is the last line executed, after which the focus shifts to another form and the OnMDIChildActivate() code is executed. And, I might add, there is plenty of code after that last line...

I'm thinking that to find the 'current' mdi form window may take lots of work for every button event and such. I'm thinking more along the lines of having to create a custom button out of images as it doesn't seem to have the "jumping focus" for anything but the buttons.

More suggestions are welcome - and no matter what I do for a solution, I would still like to find an explanation...

Remus

WM_NCLBUTTONUP

Guinness4Strength9-Jun-04 9:08

Guinness4Strength

9-Jun-04 9:08

I've not been able to trap this event in my WndProc override on my form. I did a search for this problem on this message board and saw two similar responses, anybody know anything about this ?

Re: WM_NCLBUTTONUP

Dave Kreskowiak9-Jun-04 9:49