Scratch Detection and Removal From Old Videos

8/7/2019 Scratch Detection and Removal From Old Videos

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Scratch Detection And Restoration

Why Important?

Photographic archives are being

transferred to digital form

Involves scanning of transmissive and

reflective media, namely slides or

negatives, and prints.

Inevitably introduces new artifacts such

as dust particles and scratches which

causes degradation of quality


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Why Automate?

Because of the huge number of the involved frames

Detection and Removal

The problem of automatic defect removal

is divided into two stages: detection and

removal

Detection: Defective piels identified

!econstruction: Defective piels are

replaced with estimated original piels


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Hurdles?

Inaccurate detection :"eparating true defects and

intrinsic image features, such as

edges, line segments and various

tetures.

Inaccurate detection leads to

distortion of intrinsic image

features during the reconstruction

stage


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Artiacts in Old Films

The main defect in old films are dust spots, line

scratches, abrasion, blotch, film unsteadiness

and intensity flic#er

$ine scratches are one of the most annoying

artifacts in old films

%aused by particle caught in film transport

mechanism, and when film passes over the

particles material being abraded and line

scratches are formed.


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&ll about "cratch

The width of line scratches are between '()

piels

In the center of line scratches, the intensity of

the piel shows a very little fluctuation

The level of the intensity values for line

scratches is higher than that of image edges

Typically they are vertical *angle to the verticalupto + degrees

$oss of color information in the region is

complete

*usually have bright or dar# color!


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Scratch Detection

Two ma-or types: i"patial methods

ii Temporal methods

"patial( "patial detection methods usesstrong vertical scratch property

Temporal( Trac#ing of scratch in motion

compensated image frames


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OW"#$ased line scratch detection

/0 is an undecimated wavelet transform withtranslation invariant

It locates the position of line scratches in each

scale as same as the position in the spatial domain

without any information damaged during thewavelet transform

1rom this point of view, /0 is more appropriate

than decimated wavelet transforms in image post(

processing

&llows us to design a more efficacious and

precise position

for scratch than traditional methods


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%roposed ethod

'enerali(ed Wavelet ")pansion $asedAlgorithm

To locate the line artifact and represent them

precisely, the algorithm adopts ver ( complete

/avelet 0pansion

*/0 representation of original image

&t the edge of line scratches area, hori2ontal

intensity

variation is much larger than vertical intensity

variation


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Flo*chart o Algorithm

Grey ScaleImage

ColoredImage

Im2doubleDouble values

OWE(A,H,V,D)

Sum V(Vertcal)

!ocal V"a#ma ($)

$() % $(&)'Scratc

V must ave at least *+ + as above

average

rgb2gray

"as- (tose .s)


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Steps

%onvert the image to grey scale if it is !3B andchange the values in double to apply /avelet

transform in net step.

Ta#e ver ( complete wavelet epansion */0.

&ssume that the original image has m by n piels,

and denote / v*,y as first scale vertical wavelet

decomposition coefficient at the position of *, y,

then the sum is: nV M W v (x) = W v ( x , y ), ----- (1)

y=1


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/e find the local maima and minima and chec# if

there is local maima and minima in nearby piel

based on scratch width*+ piel both side.

Based on the fact that there are sharp hori2ontal

variations at both sides of line scratches and local

maimum and local minimum will be found at the left

side and right side of linescratches respectively

xW Max={x|V MWv(x)>V MWv(x-1)&V MWv(x)>V

MWv(x+1),xZ,1


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1or actual position of scratches

& 456+ bloc# is ta#en as local bloc# image andpiel values are compared with average.

If 75 piel in a column has more or less than

average value than this column has a scratch in

particular bloc#.


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Scratched Image Scratch Detected


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!estoration

!estoration improves the sub-ective visual

quality of archive

To restore the film without causing distortion to

areas of the frames that are not affected, the

location of scratch must be located precisely

8oreover a fully automatic restoration system is

very hard to develop, because the correction of

misalignment of brightness, detection and removal

of shot and scratch, noise reduction, etc.


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&ssumption: !egions affected by scratches do

not contain original information

"olution: Propagate neighboring clean

information into the degraded area

The neighboring information can be found in thesame frame or also in the preceding and

successive frame eploiting the temporal

coherency


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Functional $loc+

diagram

Dgtal

DegradedSe/ue0ce1mage

A0alogue

DegradedSe/ue0ce1mage

ScratcDetector OWE mas-

Scratces

(!esse0 alseDetecto0)

Com3ar0g

rames(O0ly or vdeos)I0ter3olato0

$estored

Se/1mage

Dgtal E0coder


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!esult: Images scratch

removed

Scratced Image Scratc$emoved


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,HA-. /O0

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Scratch Detection and Removal From Old Videos