Bit-rate calculation in Jpeg2000 image compression

Question

I'm working on pre-processing image compression session. I'm researching on image compression methods and read lot of articles about jpeg2000 image compression. But I can't find clear resource about choosing bitrate for different layer of color image and bitrate calculation methods in jpeg2000. Please give me some clues with official references on that.

Answer 1

There is not a single correct answer. The number of layers and the bit rates associated with those layers should be set according to the needs of the users and systems which will consume the imagery.

The good news is that there is plenty of guidance! Here are two options.

Copy Kakadu

Take a look at this gist. It shows the input parameters for Kakadu's kdu_compress utility. For the -rate flag it states:

When two rates are specified, the number of layers must be 2 or more and intervening layers will be assigned roughly logarithmically spaced bit-rates. When only one rate is specified, an internal heuristic determines a lower bound and logarithmically spaces the layer rates over the range.

Kakadu is heavily used in industry and their J2K compression software is highly trusted. So if they software uses logarithmic spacing for their quality layers that might be a reasonable place to start.

Pick a profile in the BIIF Profile for JPEG 2000

On the other hand, you can take a look at the BIIF Profile for JPEG 2000 which provides several compression profiles for different situations. The profiles provides examples giving the number of layers and bit rates. That said, there is a general message across all the profiles such as:

D.4.7 (NPJE profile) of BIIF:

Some systems may change the exact bitrates and number of layers to meet application requirements or quality requirements.

F.7 (TPJE profile) of BIIF:

Note that the actual target bit rates and numbers of Quality Layers used for a specific sensor would need to be optimized to accommodate any unique properties of that particular imagery collection system.

G.2.1.2 (LPJE profile) of BIIF:

Applications need a sufficient number of codestream layers for optimal bandwidth and memory management across such a wide range of resolutions. Layers provide an elegant means to control visual quality and manage channel capacity for streaming compressed imagery over low bandwidth links... LPJE does not require a specific layer structure since the goal of this preferred encoding is to accommodate hardware and software implementations.