Methods and systems for image intra-prediction mode management

1. A method for communicating a spatial pixel prediction mode for a target block in an image, said method comprising

a. storing an ordered set of pixel prediction modes, wherein said prediction modes are ordered in order of decreasing probability of producing a lesser prediction error and wherein said order is not based on characteristics of said image;

b. determining a first adjacent mode actually used for predicting a first adjacent block, which is adjacent to a target block, wherein said first adjacent mode is selected based on an actual prediction error and said first adjacent mode is in said ordered set;

c. determining a second adjacent mode actually used for predicting a second adjacent block, which is adjacent to said target block, wherein said second adjacent mode is selected based on an actual prediction error and said second adjacent mode is in said ordered set;

d. selecting one of said first adjacent mode and said second adjacent mode as an estimated mode for said target block, wherein said selecting is based on the order of said ordered set;

e. determining an actual prediction mode for said target block by determining which mode in said ordered set results in the least prediction error;

f. sending a first signal indicating to use said estimated mode to predict said target block when said actual prediction mode is substantially similar to said estimated mode;

g. eliminating said estimated mode from said ordered set thereby creating a reduced ordered set when said actual prediction mode is not substantially similar to said estimated mode; and

h. sending a second signal indicating which prediction mode to use when said first signal indicates not to use said estimated mode.

2. A method as described in claim 1 wherein at least a portion of the modes in said ordered set are in an order as follows:

i. one mode taken from an axis subset consisting of a horizontal prediction mode and a vertical prediction mode;

j. the other mode of said axis subset; and

k. a DC prediction mode.

3. A method for communicating a pixel prediction mode for a target block in an image, said method comprising:

l. storing an ordered set of pixel prediction modes, wherein said order is not based on characteristics of said image;

m. determining a first adjacent mode actually used for predicting a first adjacent block, which is adjacent to a target block, wherein said first adjacent mode is selected based on an actual prediction error and said first adjacent mode is in said ordered set;

n. determining a second adjacent mode actually used for predicting a second adjacent block, which is adjacent to said target block, wherein said second adjacent mode is selected based on an actual prediction error and said second adjacent mode is in said ordered set;

o. selecting one of said first adjacent mode and said second adjacent mode as an estimated mode for said target block, wherein said selecting is based on the relative positions of said adjacent modes in said ordered set;

p. modifying said ordered set by moving said estimated mode from its original position in said ordered set to a new position in said ordered set thereby creating a modified ordered set.

4. A method as described in claim 3 further comprising:

q. determining an actual prediction mode for said target block by determining which mode in said ordered set results in the least prediction error; and

r. sending a prediction mode signal indicating which mode in said modified ordered set corresponds to said actual prediction mode.

5. A method for determining a pixel prediction mode for a target block in an image, said determining occurring at a decoder, said method comprising:

s. storing an ordered set of pixel prediction modes, wherein said order is not based on characteristics of said image;

t. determining a first adjacent mode actually used for predicting a first adjacent block, which is adjacent to a target block, wherein said first adjacent mode is in said ordered set;

u. determining a second adjacent mode actually used for predicting a second adjacent block, which is adjacent to said target block, wherein said second adjacent mode is in said ordered set;

v. selecting one of said first adjacent mode and said second adjacent mode as an estimated mode for said target block, wherein said selecting is based on said ordered set;

w. using said estimated mode as a prediction mode in decoding said target block when a first signal indicates to use said estimated mode;

x. eliminating said estimated mode from said ordered set thereby creating a reduced ordered set when said first signal indicates not to use said estimated mode; and

y. using a prediction mode in said reduced ordered set, said prediction mode being indicated by a second signal, when said first signal indicates not to use said estimated mode.