JPEG Compression Calculation

[rob_simkins]

Hi all,

 

I am deploying a wireless CCTV system in a club, I want to know how

large the image filesize is so that I can calculate throughput

requirements.

 

I have figured that uncomressed 8bit and 16bit images of size 320x240

are 76.8kb and 153.6kb respectively. Now I need to know an

algorithm/calculation to find its JPEG compressed size.

 

We are looking for 30fps ideally.

 

Thanks in advance, a percentage-compression figure would be excellent!

 

- Rob

[bobatkins]

Can't be done. It depends on the image content. For a given final image quality the more detail in the image, the less compression you get. You can compress as much as you want as long as you can tollerate the loss of image quality and the size of the compression artifacts.

 

So your answer probably lies in the 50%-99% range, i.e. your compressed file could be anything from 1/2 to 1/100 of the uncompressed file size.

[hugh stevens]

Rob

 

why not investigate Motion Picture Experts Group (MPEG) compression which I'm sure is suited to a 30fps protocol.

[rffffffff]

if memory serves correct, the d100 book says that fine mode offers no compression, full size files, the normal mode compresses to about 50% of original and the basic mode compresses to 25%. Its never the same size, based on content (as stated above) but it all depends on the compression factor of the equipment you are using and then your image quality tolerance. Sounds like you only need basic quality though because you wont see the difference on a TV in a million years... 25% should do if the camera will go down that far.