pipeline image compression

I have a custom made web server running that I use for scanning documents. To activate the scanner and load the image on screen, I have a scan button that links to a page with the following image tag:

<img src="http://my开发者_JAVA技巧server/archive/location/name.jpg?scan" />

When the server receives the request for a ?scan file it streams the output of the following command, and writes it to disk on the requested location.

scanimage --resolution 150 --mode Color | convert - jpg:-

This works well and I am happy with this simple setup. The problem is that convert (ImageMagick) buffers the output of scanimage, and spits out the jpeg image only when the scan is complete. The result of this is that the webpage is loading for a long time with the risk of timeouts. It also keeps me from seeing the image as it is scanned, which should otherwise be possible because it is exactly how baseline encoded jpeg images show up on slow connections.

My question is: is it possible to do jpeg encoding without buffering the image, or is the operation inherently global? If it is possible, what tools could I use? One thought I had is separately encoding strips of eight lines, but I do not know how to put these chunks together. If it is not possible, is there another compression format that does allow this sort of pipeline encoding? My only restriction is that the format should be supported by the mainstream browsers.

Thanks!

You want to subdivide the image with a space-filling-curve. A sfc recursivley subivide the surface in smaller tiles and because of it's fractal dimension reduce the 2d complexity to a 1d complexity. When you have subdivide the image you can you use this curve to continously scan the image. Or you can use a BFS and some sort of an image-low-frequency-detail filter to continuously scan higher resolution of your image. You want to look for Nick's spatial index hilbert curve quadtree blog but I don't think you can put the tiles together with a jpg format (cat?). Or you can continously reduce the resolution?

scanimage --resolution [1-150] --mode Color | convert - jpg:-