Oviyam hangs when used over the internet

[Jon Ander Zuccaro]

Greetings, I have an Oviyam installation. It is working correctly.

When accessing through the local area network everything works fine. If I publish the server and access it via the internet, for large CR images, Oviyam hangs the browser when I try to use the Window/Level tool.

I am talking about the same study/images on the same server and the same PC/Browser for accessing Oviyam, it works like a charm over LAN but if I take the PC home and access the server via the internet everything works but the Window/Level tool that causes Chrome to hang.

The hardware running the server is ver low end mind you, and both internet connections are not the best.

I guess it has to do with the size of the images because for small MR images the window level tool continues to work over the internet.

This happens with both oviyam 2.0 and 2.1

Any thoughts?

[Suresh Viswanathan]

You’re right, it’s all about the size. Uncompressed CR images can be large and if you don’t have an adequately fast connection, it probably wouldn’t work.

Suresh.

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[Jon Ander Zuccaro]

Thank you for your answer Suresh.

It is my understanding that your limitations are related to the fact that you want to accomplish real-time window/level manipulation and this is very hard and bandwidth intensive for large images but does the Oviyam team has any plans for addressing this issue? Perhaps offering a limited window/level tool for slow connections where the user could only select window/level values from a limited set of presets or maybe applying the window/level in real time only to a small region of interest of the image in some “preview” form and only when the user finally settles for a value apply it to the whole image...

Just some thoughts.

[Suresh Viswanathan]

You’ve hit the crux of the problem. Oviyam 0.9 did have presets which would be rendered server side and be pushed as a jpeg image. With Oviyam 2 we wanted to take advantage of Moore’s Law and, hopefully, proportionately increasing bandwidth speeds to accomplish realtime WL/WW.

Compared to CT & MR images CR/DX tend to be huge. We’ve taken two approaches in our experimental internal builds. The first is to use JPEG 2000 compression to reduce the size. However, since browsers do not natively support JPEG 2000 we’ve had to create a decompressor in Javascript. This works but there’s a few seconds lag while the image is uncompressed.

The second approach is to scale down the DICOM Image by half in both dimensions. The resulting image is ¼ the original size and works quite well in the browser. However you loose resolution and you’ll have to be comfortable with that.

At present there’s no timeline or even certainty for the release of either feature.

Suresh.