How to send images through a network

KansaiRobot · 01-09-2014, 02:59 AM

Hello everybody. I would appreciate some help on the following.

I have read this tutorial on Network Programming

Beej's Guide to Network Programming

It is quite useful. With this I have been able to send text over a virtual LAN connection and also over a LAN cable from one microcontroller running (a variant of ) uCLinux to a PC running a virtual Debian Linux.

So far so good.

My question is how do I send images, ergo graphic data? Can I use the same technique or have to pack the data in some way?

Is there a resource or book or tutorial which deals with this?

Any help will be greatly appreciated

Thanks

Kansai

TobiSGD · 01-09-2014, 09:00 PM

From the point of network sockets it is irrelevant which type of data you send, so you can use the same technique.

KansaiRobot · 01-09-2014, 11:41 PM

Quote:

Originally Posted by TobiSGD

From the point of network sockets it is irrelevant which type of data you send, so you can use the same technique.

Thank you very much for your response.

I understand that theoretically what you said is true. However I imagine image data is quite large, so sending it just as I did with text data has a high probability of failing (to send the whole data)

I have heard that perhaps I have to pack the data first.

Any idea of how this can be done?

Thanks!

-----------------------
P.S. So far I have ideas floating in my head, such as sending an image byte by byte... (oh mine!) or cutting it into chunks...

TobiSGD · 01-09-2014, 11:46 PM

If you use TCP error checking should be done automatically.

astrogeek · 01-09-2014, 11:48 PM

Quote:

Originally Posted by KansaiRobot

Thank you very much for your response.

I understand that theoretically what you said is true. However I imagine image data is quite large, so sending it just as I did with text data has a high probability of failing (to send the whole data)

I have heard that perhaps I have to pack the data first.

Any idea of how this can be done?

Thanks!

-----------------------
P.S. So far I have ideas floating in my head, such as sending an image byte by byte... (oh mine!) or cutting it into chunks...

Well, you don't "have" to, but you may want to gzip it (see man gzip)

If your original file was someimage.png, then you might try this...

Code:

gzip someimage.png

Then send the file someimage.png.gz...

Then on the receiving end...

gunzip someimage.png.gz

For multiple files archive them with tar (see man tar).

gdejonge · 01-10-2014, 03:09 AM

I think he is more concerned with connection loss. That is why most protocols on top of TCP/IP (like bittorent, rsync) have build-in restart options, so they can continue when a connection got lost.

@kansai if you need that restart/continue functionality, you have to add that yourself. Beej's guide will only give you the basics. Of course you could always take a peek at the way some other software does it. Afterall that's what FOSS is all about :0

Cheers

TobiSGD · 01-10-2014, 08:36 AM

Quote:

Originally Posted by astrogeek

Well, you don't "have" to, but you may want to gzip it (see man gzip)

If your original file was someimage.png, then you might try this...

Code:

gzip someimage.png

Then send the file someimage.png.gz...

Then on the receiving end...

gunzip someimage.png.gz

For multiple files archive them with tar (see man tar).

Image formats like PNG and JPG are already compressed. Using compression algorithms like gzip on them is likely to make them slightly larger, but in almost any case they will not be smaller afterwards.