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Browse Prior Art Database

ADAPTIVE EXPOSURE COLOR CORRECTION

IP.com Disclosure Number: IPCOM000026703D
Original Publication Date: 1993-Apr-30
Included in the Prior Art Database: 2004-Apr-06
Document File: 8 page(s) / 388K

Publishing Venue

Xerox Disclosure Journal

Abstract

An apparatus for correcting color images in an electrophotographic printing machine in which a first image is developed on a photoconductive surface, and onto which a second and subsequent images are superimposed over the first developed image, is disclosed. The apparatus includes an input device for inputting an image signal having a plurality of color components. An image processing unit processes the inputted signal. The image processing unit includes an adaptive exposure processor that modulates the exposure level of a raster output scanner (ROS) for a given pixel as a function of toner previously developed at the pixel site, thereby allowing toner layers to be made independent of each other.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 28% of the total text.

Page 1 of 8

XEROX DISCLOSURE JOURNAL

I I

I I

ADAPTIVE EXPOSURE COLOR Proposed Classification CORRECTION U.S. C1.355/326
Cyril G. Edmunds
William L. Lama

Int. C1. G03g 15/01

+'- SHADINGCORRECnON - 46

,

UNIT

                I MASKING UNIT --. 48

I

PROCESSING DITHER I 52 I
I .
UNIT I

I

A

I 50 I

FIG. I

P/R

+ -7 c w II

I

70 >

r II

I .

PIXEL INTERPRETER

II

II

EXPOSURE

20 ENCODER -72 60

-- I

I 76

\ AE ' '* MODULATOR -

COMPARATOR

I

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWAprill993 203

[This page contains 1 picture or other non-text object]

Page 2 of 8

ADAPTIVE EXPOSURE COLOR CORRECTION (Cont'd)

GET IMAGE e82

 SEPARATE SIGNAL INTO 4 BITMAPS Y,M,C AND BK

          I I r cl

PIXEL

&""

Q PIXEL

LOOK UP EXPOSURE AND PRINT

PIXEL

NO

t-"

FIG.2

204 XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWApril 1993

fl

PIXEL OF

 DEVELOP AND RECHARGE PHOTORECEPTOR

YES

96 98

-

[This page contains 1 picture or other non-text object]

Page 3 of 8

ADAPTIVE EXPOSURE COLOR CORRECTION (Cont'd)

1

.8

.6

ONE LAYER

YELLOW OR

MAGENTA

I I I I I I I I I

I I I I I I I

0 .2 .4 .6 .8

TWO LAYER

I I I I I
I

y

YELLOWOR

I MAGENTA I ANDCYAN I
I
I
I
I

YELLOWAND MAGENTA

   TOTAL TRANSMITTANCE

.4.

.2.

0-

Ye. /

I \*'

I'I I I

1.2 1.4 1.6 1.8

DMA (mg / cm2)

FIG. 3

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWAprill993 205

[This page contains 1 picture or other non-text object]

Page 4 of 8

ADAPTIVE EXPOSURE COLOR CORRECTION (Cont'd)

30-

1.5- 1ST LAYER

- BARE PHOTORECEPTOR 2ND LAYER

                  0.9 mg I cm2 TONER PRESENT lcm21kV mg 3.5 = Y Y = 0.82* 3.5 = 2.33mg I cm2/ kV

I

 I 1

/

0

DMA 1ST LAYER -

= 0.90 mg I cm2 -

DEVELOPMENT .5-

DMA 2ND LAYER -

= 0.32 mg I cm2 -

MASSAREA .

1000 800 NG. 4

-1 I'I I I

.5 .6 .7 .8 .9

FIG. 5 TMA (MG ICM2)

206 XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarchiApril 1993

0 200 400 600

DEVELOPMENT I VOLTS

THR0UG.I 2 ,YERS

:--- Y AND M

8

8

8

                 THROUGH 1 LAYERS 44 A--- Y AND M

/**

4CL4-f-

EXPOSURE ERGSICMZ 25 -

8 780 nm

20-

@ 15 -

14

10 -

8

5

n

 t 8

#

8

 4 4 0

4

,#*

40'

/-*

e-'

c \ THROUGH0 LAYERS

%--

..

Y AND M

[This page contains 1 picture or other non-text object]

Page 5 of 8

ADAPTIVE EXPOSURE COLOR CORRECTION (Cont'd)

n

IST READ CYCLE

FIG. 6A

I 4

-4

2ND READ CYCLE

FIG. 6B

FIG. 6C 3RD READ CYCLE

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 March/Aprill993 207

[This page contains 1 picture or other non-text object]

Page 6 of 8

ADAPTIVE EXPOSURE COLOR CORRECTION (Cont'd)

An apparatus for correcting color images in an electrophotographic printing machine in which a first image is developed on a photoconductive surface, and onto which a second and subsequent images are superimposed over the first developed image, is disclosed. The apparatus includes an input device for inputting an image signal having a plurality of color components. An image processing unit processes the inputted signal. The image processing unit includes an adaptive exposure processor that modulates the exposure level of a raster output scanner (ROS) for a given pixel as a function of toner previously developed at the pixel site, thereby allowing toner...