Java: make an low quality image

Question

In the software 'Teamviewer', the quality of the images can be changed. It looks like the image comes from 32bit to 16bit (Or other values, like in the screen device settings in Windows). The image is realy smaller because you notice that the speed of the desktop sharing gets higher. I don't want something like: "scale down, send and than scale up".

Now my question: Is it possible to make a low-quality image.

Thanks

Answer 1

Yes, you can change the compression settings for many different types of Images.

Google found this: Adjust JPEG image compression quality when saving images in Java

Answer 2

You have four alternatives for lossy compression:

• reduce spatial resolution (size)
• reduce bitdepth
• compress in another domain (JPEG)
• a combination of these

And you will probably get the best gain with JPEG for rich pictures like photos, and with bitdepth reduction (even down to using 8bit or less palette) on others with less variation in colors. Please note that bitdepth reduction is most effective if combined with lossless compression afterwards, like runlength encoding (did you know that even jpeg uses that?)

Answer 3

You can use image converters for this purpose. When user uploads a file its sent to the converter which does its thing (according to defined settings). You would however need access to run applications on the server I think.

Answer 4

ypnos already mentioned bit depth reduction. Reading your question I also immediately though of dithering, which will preserve the image better as you reduce the size of the color space. You can pretty easily find implementations of the Floyd-Steinberg algorithm around the net.