Real-time conversion of still-video to half-tone for hard copy output (such as on a facsimile machine)

• US 5,193,012 A
• Filed: 04/29/1991
• Issued: 03/09/1993
• Est. Priority Date: 04/29/1991
• Status: Expired due to Fees

• Current Assignee: Snap-Fax Corporation
• Original Assignee: Snap-Fax Corporation
• Inventors: Schmidt, Jonathan E.
• Primary Examiner(s): BRINICH, STEPHEN M
• Application Number:
  US07/693,444
• Time in Patent Office: 680 Days
• Field of Search: 358/298, 358/456, 358/444, 358/75-80, 358/909, 346/154, 346/155, 346/76 PH, 346/76 L, 346/76 R
• US Class Current: 358/3.16
• CPC Class Codes: H04N 1/00291 with receiver circuitry television receiver circuitry per se H04N5/44
• CPC Class Codes: H04N 1/00294 for printing images at a television receiver
• CPC Class Codes: H04N 2201/0067 Converting to still picture data

Abstract

A real-time still-video to facsimile conversion system (FIG. 3) converts a still-video image frame into a half-tone facsimile reproduction without having to store an entire intermediated grey-scale image frame. Conversion of a still-video image to a half-tone facsimile output is accomplished by repeatedly transmitting the still-video image frame from a still-video source to a still-video input circuit (10), with a virtual facsimile page synchronization module (20) providing synchronization to a virtual facsimile page. In successive image frames, a video pixel grabber (34) grabs successive columns of image pixels, and provides them to a half-tone pixel converter (32) for conversion to facsimile lines--for the exemplary embodiment a 3×3 half-tone pixel format is used, so that the 525 raster lines of an image pixel column are transformed into three facsimile lines using a total of 1575 dots per line (out of the standard 1728 dot facsimile line). After conversion of each column of image pixels, the corresponding facsimile lines are buffered in a facsimile multi-line buffer (36) for conventional facsimile transmission by a half-tone facsimile output module (40) to a facsimile machine for facsimile reproduction.

Claims

1. A method of real-time still-video conversion for converting a still-video image frame captured by a still-video source into a half-tone reproduction produced by a hard copy output device without requiring the creation or storage of an intermediate image frame, comprising the steps:

for each still-video image frame, receiving repeated transmissions of the still-video image frame from the 10 still-video source until conversion is complete;

for each transmission of the still-video image frame, synchronizing the frame to a virtual hard copy page the defines a matrix of virtual hard copy pixels, with each virtual hard copy pixel being associated with a corresponding image pixel of the still-video frame which is characterized by an amplitude value;

in successive still-video image frames, converting successive blocks of image pixels into corresponding blocks of half-tone pixels, with each half-tone pixel having an appropriate half-tone dot pattern; and

then

transmitting each converted half-tone pixel in a block to the hard copy output device for producing a half-tone hard copy output;

repeating this conversion process until the still-video image frame is completely converted into a half-tone hard copy.

2. The method of real-time still-video conversion of claim 1, further comprising, after the step of receiving still-video image transmissions, the step:

video processing the received still-video image frame to optimize the conversion process for the hard copy output device.

3. The method of real-time still-video conversion of claim 1, wherein the step of converting image pixels into half-tone pixels includes half-tone processing the image pixels to optimize the conversion process for the hard copy output device.

4. The method of real-time still-video conversion of claim 3, wherein half-tone processing includes adjusting the half-tone dot pattern for adjacent half-tone pixels to provide smoothing for the hard copy output.

5. The method of real-time still-video conversion of claim 1, wherein a virtual hard copy page is formed by a predetermined number of hard copy lines each with a predetermined number of half-tone dot positions, such that each virtual hard copy pixel is defined by a predetermined number of adjacent half-tone dot positions on a predetermined number of adjacent lines, thereby forming a half-tone dot-matrix.

6. The method of real-time still-video conversion of claim 5, wherein the still-video image is divided into rows and columns of image pixels, and wherein the step of converting image pixels into half-tone pixels comprises the steps of:

in successive still video image frames, grabbing successive columns of image pixels;

using a 90 degree transformation rotation, converting each column of image pixels into a corresponding number of lines of half-tone dots to form a line of half-tone pixels, with each half-tone pixel being formed by a half-tone dot-matrix with an appropriate half-tone dot pattern.

7. The method of real-time still-video conversion of claim 6, wherein the still-video image frame is formed by 525 raster lines, wherein the hard copy output device is a facsimile machine using a dot format of at least 1575 dot positions per line, and wherein the half-tone dot-matrix is a 3×

3 matrix such that each column of still-video image pixels is transformed into three hard copy lines with each still-video image pixel being assigned a corresponding half-tone pixel with three adjacent half-tone dot positions on each of the three hard copy lines.

8. The method of real-time still-video conversion of claim 1, further comprising, after the step of converting image pixels into half-tone pixels, the step of:

buffering an entire block of converted half-tone pixels prior to transmission of any of the pixels to the hard copy device.

9. The method of real-time still-video conversion of claim 8, wherein a virtual hard copy page is formed by a predetermined number of hard copy lines each with a predetermined number of half-tone dot positions, such that each virtual hard copy pixel is defined by a predetermined number of adjacent half-tone dot positions on a predetermined number of adjacent lines, thereby forming a half-tone dot-matrix, and wherein the block of converted half-tone pixels comprises an entire line of half-tone pixels formed by a corresponding number of hard copy lines.

10. The method of real-time still-video conversion of claim 9, wherein at least two lines of half-tone pixels are buffered, and wherein the step of converting image pixels into half-tone pixels includes half-tone processing the image pixels by adjusting the half-tone dot pattern for adjacent half-tone pixels on the same line and on adjacent lines to provide smoothing for the hard copy output.

11. A real-time still-video conversion system for converting a still-video image frame captured by a still-video source into a half-tone hard copy of the still-video image frame produced by a hard copy output device without requiring the creation or storage of an intermediate image frame, comprising:

a video input circuit for receiving repeated transmissions of a still-video image frame from the still-video source until conversion of that frame is complete;

a virtual page synchronizer for synchronizing each transmission of the still-video image frame to a virtual hard copy page that defines a matrix of virtual hard copy pixels, with each virtual hard copy pixel being associated with a corresponding image pixel of the still-video frame which is characterized by an amplitude value;

a half-tone transformer for converting successive blocks of image pixels from successive still-video image frames into corresponding blocks of half-tone pixels, with each half-tone pixel having an appropriate half-tone dot pattern; and

a transmitter circuit for transmitting each converted half-tone pixel in a block to the hard copy output device for producing a half-tone hard copy output;

such that successive blocks of image pixels from successive still-video image frames are converted by said half-tone pixel generator and transmitted to the hard copy output device until the still-video frame is completely converted into a half-tone hard copy.

12. The real-time still-video conversion system of claim 11, further comprising:

an input video processor for processing the received still-video image frame to optimize the conversion process for the hard copy output device.

13. The real-time still-video conversion system of claim 11, wherein the half-tone transformer performs half-tone processing of the image pixels to optimize the conversion process for the hard copy output device.

14. The real-time still-video conversion system of claim 13, wherein half-tone processing includes adjusting the half-tone dot pattern for adjacent half-tone pixels to provide smoothing for the hard copy output.

15. The real-time still-video conversion system of claim 11, wherein a virtual hard copy page is formed by a predetermined number of hard copy lines each with a predetermined number of half-tone dot positions, such that each virtual hard copy pixel is defined by a predetermined number of adjacent half-tone dot positions on a predetermined number of adjacent lines, thereby forming a half-tone dot-matrix.

16. The real-time still-video conversion system of claim 15, wherein the still-video image is divided into rows and columns of image pixels, and wherein the half-tone transformer comprises:

an image pixel grabber for grabbing, in successive still video image frames, successive columns of image pixels;

a half-tone pixel generator for converting, using a 90 degree transformation rotation, each column of image pixels into a corresponding number of lines of half-tone dots to form a line of half-tone pixels, with each half-tone pixel being formed by a half-tone dot-matrix with an appropriate half-tone dot pattern.

17. The real-time still-video conversion system of claim 16, wherein the still-video image frame is formed by 525 raster lines, wherein the hard copy output device is a facsimile machine using a dot format of at least 1575 dot positions per line, and wherein the half-tone dot-matrix is a 3×

3 matrix such that each column of still-video image pixels is transformed into three hard copy lines with each still-video image pixel being assigned a corresponding half-tone pixel with three adjacent half-tone dot positions on each of the three hard copy lines.

18. The real-time still-video conversion system of claim 11, further comprising a buffer for buffering an entire block of converted half-tone pixels prior to transmission of any of the pixels to the hard copy device.

19. The real-time still-video conversion system of claim 18, wherein a virtual hard copy page is formed by a predetermined number of hard copy lines each with a predetermined number of half-tone dot positions, such that each virtual hard copy pixel is defined by a predetermined number of adjacent half-tone dot positions on a predetermined number of adjacent lines, thereby forming a half-tone dot-matrix, and wherein the block of converted half-tone pixels comprises an entire line of half-tone pixels formed by a corresponding number of hard copy lines.

20. The real-time still-video conversion system of claim 19, wherein at least two lines of half-tone pixels are buffered, and wherein the half-tone pixel generator processes the image pixels by adjusting the half-tone dot pattern for adjacent half-tone pixels on the same line and on adjacent lines to provide smoothing for the hard copy output.

21. A method of real-time still-video conversion for converting a still-video image frame captured by a still-video source into a half-tone facsimile reproduction produced by a conventional facsimile machine without requiring the creation or storage of an intermediate image frame, comprising the steps:

for each still-video image frame, receiving repeated transmissions of the still-video image frame from the still-video source until conversion is complete;

for each transmission of the still-video image frame, synchronizing the frame to a virtual facsimile page that defines a matrix of virtual facsimile pixels, with each virtual facsimile pixel being associated with a corresponding image pixel of the still-video frame which is characterized by an amplitude value;

the virtual facsimile page being formed by a predetermined number of virtual facsimile lines each with a predetermined number of half-tone dot positions, such that each virtual facsimile pixel is defined by a predetermined number of adjacent half-tone dot positions on a predetermined number of adjacent virtual facsimile lines, thereby forming a half-tone dot-matrix;

in successive still-video image frames, converting successive blocks of image pixels into a corresponding line of half-tone pixels, each line of half-tone pixels being formed by corresponding virtual facsimile lines, and each half-tone pixel having an appropriate half-tone dot pattern;

buffering the virtual facsimile lines associated with at least one line of half-tone pixels; and

then

transmitting the buffered virtual facsimile lines to the facsimile machine for producing a half-tone facsimile output;

repeating this conversion process until the still-video image frame is completely converted into a half-tone facsimile reproduction.

22. The method of real-time still-video conversion of claim 21, further comprising, after the step of receiving still-video image transmissions, the step:

video processing the received still-video image frame to optimize the conversion process for facsimile reproduction.

23. The method of real-time still-video conversion of claim 21, wherein the step of converting image pixels into half-tone pixels includes half-tone processing the image pixels to optimize the conversion process for facsimile reproduction.

24. The method of real-time still-video conversion of claim 23, wherein half-tone processing includes adjusting the half-tone dot pattern for adjacent half-tone pixels to provide smoothing for the facsimile reproduction.

25. The method of real-time still-video conversion of claim 21, wherein the still-video image is divided into rows and columns of image pixels, and wherein the step of converting image pixels into half-tone pixels comprises the steps of:

in successive still video image frames, grabbing successive columns of image pixels;

using a 90 degree transformation rotation, converting each column of image pixels into a corresponding number of facsimile lines of half-tone dots to form a line of half-tone pixels, with each half-tone pixel being formed by a half-tone dot-matrix with an appropriate half-tone dot pattern.

26. The method of real-time still-video conversion of claim 25, wherein the still-video image frame is formed by 525 raster lines, wherein the facsimile machine uses a dot format of at least 1575 dot positions per line, and wherein the half-tone dot-matrix is a 3×

3 matrix such that each column of still-video image pixels is transformed into three facsimile lines with each still-video image pixel being assigned a corresponding half-tone pixel with three adjacent half-tone dot positions on each of the three facsimile lines.

27. The method of real-time still-video conversion of claim 26, wherein at least two lines of half-tone pixels are buffered, and wherein the step of converting image pixels into half-tone pixels includes half-tone processing the image pixels by adjusting the half-tone dot pattern for adjacent half-tone pixels on the same line and on adjacent lines to provide smoothing for the facsimile output.