Póth Miklós Fürstner Igor Subotica Tech Data compression Lossless all original data can be recovered when the file is uncompressed The signal is perfectly reconstructed from the available samples ZIP GIF PNG ID: 659046
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Slide1
Digital Image Compression Using Bit Plane Slicing Method
Póth Miklós
Fürstner Igor
Subotica TechSlide2
Data compression
Lossless - all original data can be recovered when the file is uncompressed. The signal is perfectly reconstructed from the available samples. (ZIP, GIF, PNG)
Loss
y – reduces a file by eliminating certain information. Permits reconstruction only of an approximation of the original data. (JPEG, MPEG, MP3)
SiP
201
7Slide3
Test images
SiP
2017
Cameraman
Lena
Clock
Einstein
Mandril
MRISlide4
2D-1D transformation
Prior to compression, it is needed to transform the 2D image data to 1D data.
Horizontal, vertical, Hilbert, …Slide5
Image scanning
Horizontal
Perimeter
Hilbert
Z-curve
Zig-zagSlide6
Hilbert curve
Fractal curve, self similar
Hausdorff-Besicovich
dimension 2Capable of collecting all image pixels
Applicable only to
square images
Image side must be
a power of 2Slide7
Hilbert curve scanning
Hilbert curve always takes adjacent pixelSlide8
Hilbert curve scanning
Original image Cameraman
Cameraman after Hilbert scanningSlide9
Differential encoding
Run-length coding Slide10
Bit planesSlide11
Bit planesSlide12
Bit planes
Bit planes of Cameraman image
MSB carries the contours of the image, LSB reminds of noiseSlide13
Bit planes
Question: How many bit-planes can be ignored?
How will it effect the image?Slide14
Bit planes
Question: How many bit-planes can be ignored?
How will it effect the image?Slide15
Bit planes
Question: How many bit-planes can be ignored?
How will it effect the image?Slide16
Bit planesSlide17
Bit planesSlide18
Savings
By ignoring 3 bit planes we save
3/8 = 37.5% of total image space.Slide19
Peak signal to noise ratio - PSNR
ratio
between the maximum possible power of a
signal and the power of corrupting noiseThe signal in this case is the original data, and the noise
is the error introduced by compressionSlide20
Peak signal to noise ratio - PSNR
It has been experimentally discovered that no disturbing visual artifacts are seen if
PSNR>25 dB
Quality is also based on image content, for some images it is 30 dBSlide21
Thank you for your attention.
Questions?