Digital processing apparatus and method for use in enlarging the size of an image displayed on a 2D fixed-pixel screen

• US 6,384,828 B1
• Filed: 10/22/1999
• Issued: 05/07/2002
• Est. Priority Date: 10/22/1999
• Status: Expired due to Term

• Current Assignee: Cheytec Technologies, LLC
• Original Assignee: Northshore Laboratories, Inc.
• Inventors: Bessler, Roger Frank, Arbeiter, James Henry
• Primary Examiner(s): Brier, Jeffery
• Assistant Examiner(s): BLACKMAN, ANTHONY J
• Application Number:
  US09/422,156
• Time in Patent Office: 928 Days
• Field of Search: 345/472, 345/472.2, 345/648, 345/467, 345/468, 345/469, 345/470, 345/469.1, 345/698, 345/646-647, 382/266, 382/298, 382/299, 382/300, 382/301, 382/260
• US Class Current: 345/472.2
• CPC Class Codes: G06T 3/403 Edge-driven scaling; Edge-based scaling
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 5/005 Adapting incoming signals to the display format of the display terminal
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04

Abstract

Apparatus comprising a logic member and a shear member incorporating an upsampler are used to enlarge the number of pixels in at least one image dimension by a factor F=N/M, where N is a first given-valued integer, M is a second given-valued integer and 1<N/M≦2. The shear member shears the original image at certain positions of the one dimension that are determined solely by the value of factor F, thereby introducing zero-valued shear-gap pixels at each of the certain positions. The logic member, in response to solely the 6 pixel values of those pixels within a 2×3 sub-area that borders a zero-valued shear-gap pixel at each particular certain position, fills the zero-valued shear-gap at that particular certain position with an interpolated pixel value of the original image when the logic means determines that that zero-valued shear-gap occurred at a soft edge of the original image or, alternatively, with a logically-chosen non-interpolated hard-edge object pixel value or non-interpolated background pixel value when the logic means determines that that zero-valued shear-gap occurred at a hard edge of the original image. Such apparatus is effective in substantially reducing blur in the display of hard-edge objects of an enlarged-size image on a flat-panel screen composed of a predetermined fixed number of individual light-controlling elements without adversely affecting the display of soft-edge objects of the enlarged-size image on the flat-panel screen.

Claims

1. In digital image-processing apparatus responsive to pixel values of pixels defining a digitized original two-dimensional (2D) image for increasing the number of said pixels in at least one of horizontal and vertical dimensions of said original image by a factor F=N/M, where (1) each of said pixel values falls within a range of V pixel values which extend from a quantized pixel value of 0 to a quantized pixel value of V−

1, (2) N is a first given-valued integer, (3) M is a second given-valued integer and (4) 1<

N/M≦

2;

said apparatus comprising;

shear means incorporating upsampling means responsive to said pixels defining said original image for shearing said original image at certain positions of said one dimension that are determined solely by the value of factor F, thereby introducing zero-valued shear-gap pixels at each of said certain positions; and

logic means responsive to solely the 6 pixel values of those pixels within a 2×

3 sub-area that borders a zero-valued shear-gap pixel at each particular certain position for filling the zero-valued shear-gap at that particular certain position with an interpolated pixel value of said original image in response to said logic means determining that that zero-valued shear-gap occurred at a soft edge of said original image or, alternatively, filling the zero-valued shear-gap at that particular certain position with a logically-chosen non-interpolated hard-edge object pixel value or non-interpolated background pixel value in response to said logic means determining that that zero-valued shear-gap occurred at a hard edge of said original image;

whereby the use of said digital image-processing apparatus is effective in substantially reducing blur in the display of hard-edge objects of a digitized enlarged-size 2D image on a flat-panel screen composed of at least one 2D array of a predetermined fixed number of individual light-controlling elements without adversely affecting the display of soft-edge objects of said digitized enlarged-size 2D image on said flat-panel screen.

2. The digital image-processing apparatus defined in claim 1, wherein said logic means comprises:

soft-edge processing means effective when enabled for filling said zero-valued shear-gap pixel with said interpolated pixel value;

hard-edge processing means effective when enabled for filling said zero-valued shear-gap pixel with said logically-chosen non-interpolated hard-edge object pixel value or non-interpolated background pixel value; and

edge contour switch means for applying an enabling signal to said soft-edge processing means only if the absolute value |L−

C|<

T1 and applying an enabling signal to said hard-edge processing means only if the absolute value |L−

C|≧

T1, where L is the pixel value of that second ordinal one of the 3 pixels of said 2×

3 sub-area which borders one side of said zero-valued shear-gap pixel, C is the pixel value of that that second ordinal one of the 3 pixels of said 2×

3 sub-area which borders the other side of said zero-valued shear-gap pixel, and T1 is a relatively high threshold having a given value such that V>

T1>

V/2.

3. The digital image-processing apparatus defined in claim 2, wherein:

V equals 256; and

T1 equals 150.

4. The digital image-processing apparatus defined in claim 2, wherein said hard-edge processing means comprises:

diagonally connectivity measurement means for determining whether or not the absolute value |DT−

C|<

T2, |DB−

C|<

T2, |T−

L|<

T2 or |B−

L|<

T2, where DT is the pixel value of that first ordinal one of the 3 pixels of said 2×

3 sub-area which occurs on said one side of said zero-valued shear-gap pixel, DB is the pixel value of that third ordinal one of the 3 pixels of said 2×

3 sub-area which occurs on said one side of said zero-valued shear-gap pixel, T is the pixel value of that first ordinal one of the 3 pixels of said 2×

3 sub-area which occurs on the other side of said zero-valued shear-gap pixel, and B is the pixel value of that third ordinal one of the 3 pixels of said 2×

3 sub-area which occurs on the other side of said zero-valued shear-gap pixel, and T2 is a relatively low threshold having a given value such that V/2>

T2>

0;

means responsive to the distribution of pixel values within an X×

Y sub-area of pixel values of said original image bordering said shear-gap pixel, where X>

3 and Y>

3, for assigning that pixel value which occurs most often in said distribution as said background pixel value; and

diagonally connectivity decision means for filling said zero-valued shear-gap pixel with a predetermined one of said L and C pixel values only in response to at least one of said diagonally-connectivity measured absolute values |DT−

C|, |DB−

C|, |T−

L| and |DT−

C| being less than the threshold value T2 and otherwise filling said zero-valued shear-gap pixel with said background pixel value.

5. The digital image-processing apparatus defined in claim 4, wherein:

V equals 256;

T1 equals 150; and

T2 equals 30.

6. The digital image-processing apparatus defined in claim 4, wherein:

said means responsive to the distribution of pixel values comprises 5×

5 sub-area histogram means.

7. The digital image-processing apparatus defined in claim 4, wherein:

said predetermined one of said L and C pixel values is said pixel value C.

8. The digital image-processing apparatus defined in claim 4 wherein:

said soft-edge processing means is effective when enabled for substituting a second interpolated value for a predetermined one of said L and C pixel values.

9. The digital image-processing apparatus defined in claim 8, wherein:

said predetermined one of said L and C pixel values is said pixel value C.

10. The digital image-processing apparatus defined in claim 8, wherein said digital image-processing apparatus further comprises:

select means including map into sheared image means for deriving said enlarged-size image as an output from said map into sheared image means by (1) mapping said first-mentioned and second interpolated values into the sheared image derived by said shear means in response to said soft-edge processing means being enabled and (2) mapping said predetermined one of said L and C pixel values or said background pixel value from said diagonally connectivity decision means into the sheared image derived by said shear means in response to said hard-edge processing means being enabled.

11. The digital image-processing apparatus defined in claim 10 wherein:

in response to said soft-edge processing means being enabled, said map into sheared image means maps all pixel values of said enlarged-size image output derived therefrom, other than said first-mentioned and second interpolated values, in a one-to-one correspondence with pixel values of said original image; and

in response to said hard-edge processing means being enabled, said map into sheared image means maps all pixel values of said enlarged-size image output derived therefrom, other than all filled shear-gap pixels, in a one-to-one correspondence with pixel values of said original image.

12. In a digital image-processing method responsive to pixel values of pixels defining a digitized original two-dimensional (2D) image for increasing the number of said pixels in at least one of horizontal and vertical dimensions of said original image by a factor F=N/M, where (1) each of said pixel values falls within a range of V pixel values which extend from a quantized pixel value of 0 to a quantized pixel value of V−

1, (2) N is a first given-valued integer, (3) M is a second given-valued integer and (4) 1<

N/M≦

2;

said method comprising the steps of;

(a) upsampling said pixels defining said original image for shearing said original image at certain positions of said one dimension that are determined solely by the value of factor F, thereby introducing zero-valued shear-gap pixels at each of said certain positions; and

(b) in response to solely the 6 pixel values of those pixels within a 2×

3 sub-area that borders a zero-valued shear-gap pixel at a particular certain position, logically determining whether that zero-valued shear-gap occurred at a soft edge or, alternatively, at a hard edge;

(c) filling the zero-valued shear-gap at that particular certain position with an interpolated pixel value of said original image in response to said zero-valued shear-gap having been logically determined to be a soft edge; and

(d) filling the zero-valued shear-gap at that particular certain position with a logically-chosen non-interpolated hard-edge object pixel value or non-interpolated background pixel value in response to said zero-valued shear-gap having been logically determined to be a hard edge;

whereby the use of said digital image-processing method is effective in substantially reducing blur in the display of hard-edge objects of a digitized enlarged-size 2D image on a flat-panel screen composed of at least one 2D array of a predetermined fixed number of individual light-controlling elements without adversely affecting the display of soft-edge objects of said digitized enlarged-size 2D image on said flat-panel screen.