Removal of interpolation artifacts in a non-interlaced video stream

• US 6,297,847 B1
• Filed: 08/03/1998
• Issued: 10/02/2001
• Est. Priority Date: 08/03/1998
• Status: Expired due to Term

• Current Assignee: S3 Graphics Co., Ltd. (HTC Corporation)
• Original Assignee: S3 Graphics Co., Ltd. (HTC Corporation)
• Inventors: Fisch, Eberhard H.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Yenke, Brian P.
• Application Number:
  US09/128,397
• Time in Patent Office: 1,156 Days
• Field of Search: 348/447, 348/448, 348/449, 348/458, 348/910
• US Class Current: 348/447
• CPC Class Codes: G06T 2200/28 involving image processing hardware
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G09G 2310/0229 De-interlacing
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T
• CPC Class Codes: H04N 7/012 Conversion between an interlaced and a progressive signal for graphics images G09G2310/0229
• CPC Class Codes: Y10S 348/91 Flicker reduction

Abstract

Visible artifacts introduced into a digitally sampled video signal are removed from a non-interlaced version of the video signal. The non-interlaced version of the video signal is generated by a converter that converts a digitally sampled interlaced video stream to a non-interlaced video stream. An artifact removal module responds to at least a first component of the non-interlaced video stream by adaptively modifying the first component of the non-interlaced video stream to reduce artifacts introduced into the non-interlaced video stream by the converter to generate a modified non-interlaced video stream.

Claims

1. An apparatus comprising:

a converter for converting a digitally sampled interlaced video stream to a non-interlaced video stream; and

an artifact masker, responsive to at least a first component of said non-interlaced video stream, for adaptively modifying said first component of said non-interlaced video stream to reduce artifacts introduced into said non-interlaced video stream by said converter to generate a modified non-interlaced video stream, wherein said masker comprises;

a first processing module responsive to said non-interlaced video stream for performing a first processing function on said non-interlaced video stream;

a second processing module responsive to said non-interlaced video stream for performing a second processing function on said non-interlaced video stream; and

a third processing module responsive to said non-interlaced video stream for selecting output of said first processing module or said second processing module to generate said modified non-interlaced video stream.

2. Apparatus comprising:

a converter for converting a digitally sampled interlaced video stream to a non-interlaced video stream; and

an artifact masker, responsive to at least a first component of said non-interlaced video stream, for adaptively modifying said first component of said non-interlaced video stream to reduce artifacts introduced into said non-interlaced video stream by said converter to generate a modified non-interlaced video stream, wherein said masker comprises;

a first processing module responsive to said non-interlaced video stream for performing a first processing function on said non-interlaced video stream;

wherein said first processing module comprises;

a vertical low-pass filter, responsive to said non-interlaced video stream for generating a first filtered signal; and

a horizontal low-pass filter, responsive to said first filtered signal for said output of said first processing module;

a second processing module responsive to said non-interlaced video stream for performing a second processing function on said non-interlaced video stream; and

a third processing module responsive to said non-interlaced video stream for selecting output of said first processing module or said second processing module to generate said modified non-interlaced video stream.

3. Apparatus as set forth in claim 2 wherein said vertical low-pass filter reduces resolution of vertical transitions in images represented by said non-interlaced video stream.

4. Apparatus as set forth in claim 3 wherein said horizontal low-pass filter reduces resolution of horizontal transitions in images represented by said non-interlaced video stream.

5. Apparatus as set forth in claim 3 wherein said vertical low-pass filter is a three-tap type filter.

6. Apparatus as set forth in claim 4 wherein said horizontal low-pass filter is a seven-tap type filter.

7. Apparatus comprising:

a converter for converting a digitally sampled interlaced video stream to a non-interlaced video stream; and

an artifact masker, responsive to at least a first component of said non-interlaced video stream, for adaptively modifying said first component of said non-interlaced video stream to reduce artifacts introduced into said non-interlaced video stream by said converter to generate a modified non-interlaced video stream, wherein said masker comprises;

a first processing module responsive to said non-interlaced video stream for performing a first processing function on said non-interlaced video stream;

a second processing module responsive to said non-interlaced video stream for performing a second processing function on said non-interlaced video stream; and

a third processing module responsive to said non-interlaced video stream for selecting output of said first processing module or said second processing module to generate said modified non-interlaced video stream, wherein said third processing module comprises;

a binary edge detection module, responsive to said non-interlaced video stream for generating an edge detect signal indicative of a non-horizontal transition in images represented by said non-interlaced video stream;

a magnitude module, responsive to said edge detect signal, for generating a magnitude signal indicative of magnitude of said edge detect signal;

a comparator, responsive to said magnitude signal, for generating a comparison signal, indicative of a comparison between said magnitude signal and a stored threshold value; and

a delay module, responsive to said comparison signal, for time delaying said comparison signal by a predetermined time delay value, to generate said output of said second processing module.

8. Apparatus comprising:

a converter for converting a digitally sampled interlaced video stream to a non-interlaced video stream; and

an artifact masker, responsive to at least a first component of said non-interlaced video stream, for adaptively modifying said first component of said non-interlaced video stream to reduce artifacts introduced into said non-interlaced video stream by said converter to generate a modified non-interlaced video stream, wherein said masker comprises;

a first processing module responsive to said non-interlaced video stream for performing a first processing function on said non-interlaced video stream, wherein said first processing module comprises means for reducing resolution of images represented by said non-interlaced video stream;

a second processing module responsive to said non-interlaced video stream for performing a second processing function on said non-interlaced video stream; and

a third processing module responsive to said non-interlaced video stream for selecting output of said first processing module or said second processing module to generate said modified non-interlaced video stream.

9. Apparatus comprising:

a converter for converting a digitally sampled interlaced video stream to a non-interlaced video stream;

an artifact masker, responsive to at least a first component of said non-interlaced video stream, for adaptively modifying said first component of said non-interlaced video stream to reduce artifacts introduced into said non-interlaced video stream by said converter to generate a modified non-interlaced video stream, wherein said masker comprises;

a first processing module responsive to said non-interlaced video stream for performing a first processing function on said non-interlaced video stream;

a second processing module responsive to said non-interlaced video stream for performing a second processing function on said non-interlaced video stream, wherein said second processing module comprises;

a delay module, responsive to said non-interlaced video stream for time delaying said non-interlaced video stream by an amount equal to a time delay introduced by said first processing module, to generate said output of said second processing module; and

a third processing module responsive to said non-interlaced video stream for selecting output of said first processing module or said second processing module to generate said modified non-interlaced video stream.

10. Apparatus as set forth in claim 9 wherein said delay module comprises:

a line delay module for delaying said non-interlaced video stream by one scan line; and

at least a first pixel delay module coupled to receive output of said line delay module for delaying said non-interlaced video stream by one pixel.

11. Apparatus as set forth in claim 9 wherein said stored threshold value is a programmable value.

12. A method for removing artifacts introduced into an image by conversion of said image from an interlaced format to a non-interlaced format comprising:

generating a selection signal by performing non-horizontal edge detection upon a signal indicative of said non-interlaced format;

adaptively filtering said signal indicative of said non-interlaced format to generate a reduced resolution signal;

delaying said signal indicative of said non-interlaced format by an amount equal to a delay introduced into said filtered signal to generate a delayed signal; and

selecting said reduced resolution signal or said delayed signal as a function of said selection signal.

13. A graphics processor comprising:

a scan conversion module, responsive to an interlaced signal for generating a non-interlaced signal as a function of interpolation of scan lines of said interlaced signal;

an edge detector, responsive to said non-interlaced signal, for detecting non-horizontal transitions in images represented by said non-interlaced signal to generate a selection signal;

a filter, responsive to said non-interlaced signal, for generating a filtered non-interlaced signal having lower resolution than the resolution of said non-interlaced signal;

a delay module, responsive to said non-interlaced signal, for generating a time delayed non-interlaced signal; and

a selector for selecting between said time delayed non-interlaced signal and said filtered non-interlaced signal as a function of said selection signal.