Halftoning almost-final report

The influence of mask size
The variant method
The basic method dealing with one kind of leftout and without dealing the leftout from isolated pixelsThe basic method dealing with both kinds of leftout

PSNR
MSSIM

The variant method(6 out of 12 better than Pang method in tone matching and 12 out of 12 better in structure matching):

Dealing with the two kinds of residue: 1: some leftout from fully-filled pixels after several-time distributions in the mask and 2: leftout from isolated pixels

Using a map to store the residues, when a pixel is popped up from the heap, it will check the mask to find out if there are some residues in this mask; if there are it will carry these residues on the current error. Then the modified error will be distributed in the mask based the weight strategy.

Parameters: k1 = 1; k2 = 2; masksize 7 by 7; takes 4.625 seconds(*********This speed is not better than SAED method with the same size of mask, but better if considering the quality)

************************SAED speed analysis *******************

Kernel size CPU GPU

4 × 4 1.18 0.04

8 × 8 2.27 0.23

16 × 16 6.74 0.75----their best tradeoff

32 × 32 26.31 15.09

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The basic method(10 out of 12 better than Pang method in tone matching and 9 out of 12 better in structure matching) :

Without ordering and processing it by raster scanning order, deal with the first class residue only. The isolated situation is ignored. If dealing with the isolated situation, the artefacts are very clear.

Parameters: k1 = 20; k2 = 2.25; masksize 7 by 7; takes 0.864 seconds