Strange problem: Images damaged by internet connection

How is this happening?

[kapow]

I am experiencing a strange problem with images (new to me). Has anyone heard of internet connection that can damage/alter images when uploaded? If so whats going on? How can I avoid it?

When I collect JPEG images from the web server (they were uploaded by my Designer), then I move them to a new location and re-upload them, The images go fuzzy (like a jpeg with too much compression).
- The images look fine online before I collect them,
- They look fine if I view them locally on my PC after collecting them,
- They only look bad online after I re-upload them!
- Here is the most odd part: If I collect one that I have just uploaded to a different location, it looks fine when viewed locally!

I suspect it is something to do with the 'PUT' operation and my temporary internet connection. Note: My rooter has broken today so I am using a mobile broadband device for internet connection. The device is a modem that plugs into a USP socket on my PC, it is supplied by one of the major mobile phone companies.

ps: It might not be my mobile broadband device - I am just assuming it is the cause because nothing else has changed.

[willybfriendly]

Make sure that you are uploading a binary file. Sounds to me like you may be uploading as text/ASCII. You can usually set the transfer type to auto in your FTP program.

[JS_Harris]

What willybfriendly said - check your ftp settings.

[kapow]

I use Dreamweaver, can't find uploading format (text/ASCII). Anyone know where this is in DW?

[kaled]

I doubt this has anything to do with ftp transfers, etc. If the wrong transfer method was used, the image would be entirely corrupted.

It is most likely due to image stretching. Somewhere, the size of the image is being changed. Maybe its being changed twice so that is ends up the same size (but fuzzy).

Kaled.

[Ocean10000]

FYI Some mobile providers use a proxy server to cache files and sometimes this proxy server will recompress the images downloaded for the mobile phone to reduce the image size and bandwidth requirements.

Just a Thought.

You might want to try another connection to see if the fuzzyness happens on that connection as well.

[kapow]

Got my router working again and its fine again. I need to test that mobile-broadband-modem. I have a bad feeling it is messing with the images. Would really appreciate anyones experience with this.

[Philosopher]

So you were using the mobile broadband modem when you were uploading the images to your server?

If so, that may well be the cause. As Ocean10000 said, they were likely compressing the image to help with upload/download times.

[thecoalman]

Are you using any of those "web accelerator" programs? Most of the "web acceleration" done by ISP's like AOL is done by compressing images.