An approach for Window/Level in a browser

Posted by Martin P in Development, PACS General      1 comment

Jan
30

As I noted last week, a basic feature of access to Radiography – Window/Level – is unsupported by browsers without resorting to pseudo-thick client options like ActiveX or Java. Here is a possible approach:

We start off not with W/L, but by implementing zoom. Inspired by this excellent Apache web server add-on (unfortunately the demos are broken at present but take a look anyway for the methodology). The basis of this is that when viewing an image of, say 3000×2000 pixels in a browser at 100% zoom – only a portion of the image is visible – say 700×400. In fact, whatever zoom level, only 700×400 pixels are visible. If the server resizes the image to be the appropriate size for the browser window, then an image of only 700×400 is transferred instead of 3000×2000, reducing network traffic. IIPImage reduces the load on the server by starting off with hierarchical TIFF files, which maintain the image at several resolutions. Panning a zoomed image is then a matter of incrementally downloading tile slices depending on which direction the pan is moving.

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What are the benefits of Open Source ?

Posted by Martin P in Open Source      1 comment

Jan
27

Many people labour under the illusion that Open Source projects reap benefits from having the source code written by unpaid (at least by the project) volunteers. True, for the most successful projects this is indeed a benefit, but not the most significant. The bottom line is, writing code is easy. Writing solid, secure code is a little less easy, but writing useful code is tough, especially when the user community and the developer community do not overlap by 100%.

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And another problem with web access to PACS…

Posted by Martin P in Development, PACS General      No comments

Jan
15

….. at the moment, it is limited to Java or (more often, unfortunately,) ActiveX. Why? In this age where AJAX can make a web browser look to all intents and purposes like a ‘traditional’ thick client, why can reasonable access to a PACS server not happen via a browser without resorting to browser extensions (some of which, browser-exclusive)?

The answer is both simple and important. Window/Level. While the popularity of ActiveX as a mode of delivery is largely to do with cache management – a subject that I’ll come back to at a later point – it is also down to good, old-fashioned, Window/Level. A feature that realistically, no display implementation can do without.

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Results from the straw poll

Posted by Martin P in PACS General, Project matters      No comments

Jan
1

So, for the last month or so I had open a brief poll on why sites who do not have PACS are in that position. The results are below in MS Office Excel format, as well as Open Document Format (Open Office). The number of responses is modest (19), largely as the promotion of the poll was largely through discussion boards and mailing lists. However, since there was no suggestion of reward at the end, I think it can be assumed that those completing the survey did so in good faith, although I did weed out a couple of responses that were clearly at odds with that assumption. On the whole, for a web survey, despite the modest sample size, I think the data quality is fair.

Here’s the results:

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