Video to digital converter

• US 4,417,276 A
• Filed: 04/16/1981
• Issued: 11/22/1983
• Est. Priority Date: 04/16/1981
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Strange, Donald R., Bennett, Matthew C.
• Primary Examiner(s): RICHARDSON, ROBERT
• Application Number:
  US06/254,771
• Time in Patent Office: 950 Days
• Field of Search: 358/12, 358/13, 358/127, 358/133, 358/180, 358/185, 358/160, 358/903, 358/96, 358/260, 358/140, 358/138, 358/335, 364/515, 340/146.3 MA
• US Class Current: 375/240.01
• CPC Class Codes: H04N 1/40068 Modification of image resolution, i.e. determining the values of picture elements at new relative positions H04N1/3935 takes precedence
• CPC Class Codes: H04N 7/24 Systems for the transmission of television signals using pulse code modulation H04N21/00 takes precedence

Abstract

A method and apparatus by which video signals can be converted to digitized values and stored in memory. Means are provided for continuous digitization of successive images which may be stored in computer memory in real time. Additionally, means are provided for compression of adjacent picture elements to produce a spacially compressed image which takes up less memory space. Also disclosed are means for compressing successive frames so as to produce a temporally compressed image.

Claims

1. A system for digitizing a video signal of a plurality of horizontal scanning lines and storing the digitized signal in a computer memory comprising:

(a) means for converting an analog signal to digital form to establish digital values corresponding to relative luminance of the video signal;

(b) first counter means for establishing X-coordinates of a predetermined number of picture elements corresponding to a horizontal line;

(c) means for assigning said luminance values to said corresponding X-coordinates;

(d) means for resetting said first counter when said predetermined number is reached indicating the end of a scanning line;

(e) second counter means incremented by said resetting means for establishing Y-coordinates corresponding to horizontal lines of said video signal, whereby a main matrix of picture elements having X and Y coordinates and a luminosity value is defined;

(f) means for resetting said second counter when a predetermined number of horizontal lines is reached;

(g) means for generating coordinates of a sub-matrix which falls within said matrix;

(h) comparator means for generating an active signal for each picture element falling within said predefined sub-matrix region;

(i) horizontal compression means activated by said active signal for comparing the luminance of successive groups of predetermined numbers of horizontally adjacent picture elements within said sub-matrix region and generating successive single horizontally compressed picture elements to be substituted for said groups;

(j) buffer means for serially receiving said horizontally compressed picture elements in real time and outputting said elements at a slower rate;

(k) vertical compression means for comparing groups of horizontally compressed picture elements which are vertically adjacent and for generating successive image elements to be substituted therefor;

(l) means for addressing and storing said image elements in a computer memory for later revival and restoration to a video image.

2. The system according to claim 1 wherein said horizontal and vertical means includes means for selecting the most luminous element of each group.

3. The system according to claim 1 wherein said horizontal and vertical compression means includes means for selecting the rightmost in each group of said horizontally adjacent picture elements and selecting the uppermost of each group of vertically adjacent compressed picture elements.

4. The system according to claim 1 wherein said comparator means compares the X-coordinate of the picture element to the generated sub-matrix coordinate periodically, said period being greater than one count on said first counter.

5. The system according to claim 1 wherein said horizontal and vertical compression means includes means for selecting the approximate average of each group of said elements.

6. A system according to claim 5 wherein said storing means includes:

(a) horizontal compression means for successively substituting a single luminance value for the luminance values of a predetermined number of horizontally adjacent picture elements;

(b) vertical compression means for successively substituting a single luminance value for the luminance value of a predetermined number of horizontally compressed picture elements to produce an image element; and

(c) means for addressing and storing successive image elements in computer memory.

7. A system for digitizing a video signal and storing the signal in a computer memory comprising:

(a) an analog to digital converter for digitizing the amplitude corresponding to the varying luminance across a video line;

(b) means for generating from the video signal a first signal indicating the beginning of each horizontal line, a second signal indicating the next horizontal line, a third signal indicating the end of each image field, and a clock signal;

(c) horizontal coordinate counter reset by said first signal and incremented by said clock signal for counting up to a predetermined number;

(d) vertical coordinate counter incremented by said second signal and reset by said third signal to count to a predetermined number whereby said horizontal and vertical counters generate coordinates of a main matrix;

(e) means for assigning said coordinates to said digitized luminance values;

(f) means for generating boundary coordinates within said main matrix for defining a sub-matrix of interest;

(g) comparator means for successively comparing said boundary coordinates with the values in said counters to determine areas of intersection, and generate a fourth signal; and

(h) means activated by said fourth signal for storing in computer memory said digital luminance values within said areas of intersection.

8. A system for compressing and recording video signals in a digital memory in real time, comprising:

(a) electronic memory for storing digital signals;

(b) means for electronically defining a portion of a video image to be recorded;

(c) means for producing a vertical active signal simultaneously with the beginning of a video line, said signal being generated whenever any part of said line falls within said defined portion of the video image;

(d) means activated by said vertical active signal for producing a horizontal active signal, said horizontal signal being generated during the interval the video signal is within said defined portion of the video image;

(e) digitizing means activated by said horizontal active signal for digitizing the video signal, producing a corresponding series of digital signals;

(f) first compression means activated by said horizontal active signal and operatively connected to said digitizing means for producing a horizontal replacement signal for replacement of a contiguous plurality of said digital signals;

(g) buffer means operatively connected to said first compression means for temporally buffering the transfer of said horizontal replacement signals from said first compression means;

(h) first memory interface means connected to said buffer means and said memory for transfering said horizontal replacement signals from said buffer means to said memory; and

(i) second compression means activated by said vertical active signal and connected to said memory and said buffer for producing a vertical replacement signal for replacement in memory of a plurality of horizontal replacement signals received from said first compression means and said memory, said horizontal replacement signals corresponding to vertically contiguous video image areas.

9. A system for digitizing a video signal of successive images and subtracting from each a reference image and storing the result in a computer memory, comprising:

(a) means for converting an analog video signal to a digital form establishing a matrix of picture elements forming an image, each element having a numerical level corresponding to luminosity;

(b) means for reversing the mathematical signs corresponding to each numerical value so that a negative of said image is created;

(c) means for storing said values of said negative image in addressed locations in memory;

(d) image subtraction means for retrieving said negative values from memory, adding said negative values to values corresponding to the next successive image, and producing an image of composite values; and

(e) means for storing said image of composite values in memory.

10. A system for compressing raw image data derived from successive video images comprising:

(a) conversion means for converting an analog signal representative of the said raw image data into corresponding raw digital luminosity values comprised of a plurality of gray-scale bits;

(b) matrix means for assigning matrix addresses to each of said digital values;

(c) sub-matrix means for dividing said main matrix in accordance with a predetermined image-independent format into a selected plurality of sub-matrices, each of which encompasses predetermined ones of said addresses; and

(d) reduction means for compressing the raw digital luminosity values found in each of said sub-matrices into a plurality of compressed luminosity values comprised of a plurality of gray-scale bits wherein said sub-matrices are represented by a single compressed luminosity value.

11. A system as claimed in claim 10 wherein said reduction means provides a compressed luminosity value which is equal to the brightest value of all of the elements in a sub-matrix.

12. A system as claimed in claim 10 wherein said reduction means provides a compressed luminosity value which is substantially the average luminosity value for all elements in a sub-matrix.

13. A system as claimed in claim 10 wherein said reduction means produces a compressed luminosity value which is substantially equal to one of said luminosity values of a sub-matrix.

14. A system as claimed in claim 10 wherein said video images are formed from an interlaced scan and part of each sub-matrix is generated from each of the interlaced scan patterns that form said interlaced scan.

15. A system as claimed in claim 10 wherein said reduction means compresses the raw digital luminosity values into horizontal and vertical components in an independently adjustable manner.

16. A system for compressing and recording successive images formed from synchronous video signals in a digital memory in real time, comprising:

(a) electronic memory for storing digital signals;

(b) means for electronically defining a portion of a video image to be recorded;

(c) means for producing a vertical active signal simultaneously with the beginning of a video line, said signal being generated whenever any part of said line falls within said defined portion of the video image;

(d) means activated by said vertical active signal for producing a horizontal active signal, said horizontal signal being generated during the interval the video signal is within said defined portion of the video image;

(e) digitizing means activated by said horizontal active signal for digitizing the video signal, producing a corresponding series of digital signals;

(f) first compression means activated by said horizontal active signal and operatively connected to said digitizing means for producing a horizontal replacement signal for replacement of a contiguous plurality of said digital signals;

(g) buffer means operatively connected to said first compression means for temporally buffering the transfer of said horizontal replacement signals from said first compression means;

(h) first memory interface means connected to said buffer means and said memory for transferring said horizontal replacement signals from said buffer means to said memory; and

(i) second compression means activated by said vertical active signal and connected to said memory and said buffer for producing a vertical replacement signal for replacement in memory of a plurality of horizontal replacement signals received from said first compression means and said memory, said horizontal replacement signals corresponding to vertically contiguous video image areas.