Method for processing image data

1. A method for processing image data, comprising the steps of:

scanning at least one section of a form raster-like;

converting said scanned form into a digital image comprising picture elements, a color of each and every picture element being presented according to the HSB color presentation at hue H, saturation S and brightness B;

determining, from a membership function zUBB via said brightness or from a membership zUBS via said saturation, in conformity with a fuzzy technique, memberships ZUBB and ZUBS of said color of each and every picture element in a first color class UB;

determining, from a membership function zSBB via said brightness B, a membership function zSFS via said saturation S, or from a membership function zSFH via said hue H, memberships ZSFB, ZSFS and ZSFH of said color of each and every picture element in a second color class SF;

determining, from a membership function zBFB via the brightness B, a membership function zBFS via the saturation S, or from a membership function zBFH via the hue H, memberships ZBFB, ZBFS an ZBFH of said color of each and every picture element in at least one third color class BF;

determining minimum values

UB MIN=( ZUBB, ZUBS ),

SF MIN=( ZSFB, ZSFS, ZSFH ), and

BF MIN=( ZBFB, ZBFS, ZBFH )

of said memberships ZUBB, ZUBS, ZSFB, ZSFS, ZSFH, ZBFB, ZBFS, ZBFH in respective color classes UB, SF, BF;

determining a maximum value M among said minimum values UBMIN, SFMIN, BFMIN;

allocating a respective color as well as picture elements belonging to this color to a color class UB, SF, BF that belongs to said maximum value M; and

allocating, depending on identified said color class UB, SF, BF, a gray scale value GW to a respective picture element.

2. The method according to claim 1 , further comprising the steps of:

converting said value of the brightness B of a picture element into a scaled brightness Y with a value range 0 through 1; and

defining said gray scale value GW depending on said scaled brightness Y.

3. The method according to claim 2 , wherein said scaled brightness Y is allocated to said respective picture element as a gray scale value GW when said maximum value M belongs to said first color class UB.

4. The method according to claim 2 wherein said gray scale value GW is allocated to said picture element according to the relationship

GW =MIN ( Y , 1- SF MIN)

when said maximum value M belongs to said second color class SF.

5. The method according to claim 2 , characterized in that the gray scale value is allocated to the picture element according to the relationship

GW =MAX ( Y, BF MIN)

when the maximum value M belongs to the third color class BF.

6. The method according to claim 1 , further comprising the steps of:

determining a value L for each picture element according to the relationship

L =MAX( UB MIN, SF MIN, BF MIN); and

forming a value SOMIN according to the relationship

SO MIN=1 =L

where SOMIN is the membership of the picture element in a fourth color class SO.

7. The method according to claim 6 , further comprising the step of allocating a minimum value from said scaled brightness Y and a value 1-SOMIN is allocated to a respective picture element of said fourth color class SO as a gray scale value GW according to the relationship

GW =MIN( Y , 1- SO MIN).

8. The method according to claim 6 , wherein said fourth color class SO has colors F allocated to it that do not belong to any other color class UB, BF, SF.

9. The method according claim 1 , wherein said membership function ZUBB or ZUBS for brightness value B or, respectively, saturation values S between a minimum value UBB1 and a maximum value UBB2 has the value 0.

10. The method according to claim 9 , wherein said membership function zUBB or zUBS for low brightness values B and high brightness values B or, respectively, for low saturation values S and high saturation values S, has a rectangular, triangular, trapezoidal or an S-shaped curve in the fashion of a half-bell curve.

11. The method according to claim 1 , further comprising the step of:

presenting a frequency of occurrence with which picture elements with specific hues H occur in at least one section of said form in the form of a frequency distribution over the hue H, said membership functions ZSFH, zBFH in regions with hues H from this frequency distribution having a rectangular, triangular, trapezoidal or an S-shaped curve in the fashion of a half-bell or a whole bell curve.

12. The method according to claim 1 , wherein said membership functions zSFB, zSFS, zBFB, zBFS have a rectangular, triangular, trapezoidal or an S-shaped curve in the fashion of a half-bell or a whole-bell curve.

13. The method according to claim 1 , wherein colors with which payload information are applied on said form are mainly allocated to said second color class SF.

14. The method according to claim 1 , wherein colors F with which scatter information are applied on said form are mainly allocated to said third color class BF.