Week 3 - BPCS Algorithm

Question 1

What is the BPCS Algorithm?

Answer 1

used to hide data within pixels but in a complex way, ensuring minimal difference to payload

Question 2

How does the BPCS algorithm differ from the Least Significant Bit (LSB) algorithm?

Answer 2

LSB changes the lsb bits

BPCS analyses the complexity of bitplanes to determine where data can be hidden

Question 3

What is a bitplane?

Answer 3

A matrix created with the i bit of each pixel

e.g
make a 3x3 matrix with the LSB of each pixel in a 3x3 image

Question 4

Why are the most significant bitplanes more visually important?

Answer 4

Changes to the most significant bitplanes cause noticeable alterations in the image,

Question 5

How does BPCS determine where to hide data in an image?

Answer 5

identifies bitplanes with high complexity, as these areas can be modified without creating noticeable distortions.

Question 6

What is segmentation in the BPCS algorithm?

Answer 6

bitplanes are split into smallerblocks of 8 x 8 bits

Question 7

What is a checkerboard pattern in the context of BPCS?

Answer 7

bits in segmentation are alternating in 1s + 0s

Question 8

How is complexity calculated?

Answer 8

1. border = NO. changes in rows + NO. changes in columns
2. Max border = total NO. chekerboard pattern changes
3. Complexity = border/ Max border
4. complex if > 0.3

Question 9

BPCS Algorithm

Answer 9

1. Get the next bitplane.
2. Get next complex segment.
3. Get next payload 8x8 block.
4. IF payload is complex hide in Segment (bit flipping)
5. ELSE Conjuage ( XOR with checkerboard segment)
6. Repeat until all payload is hidden or the image capacity is reached.