Real-time edge processing unit

• US 4,213,150 A
• Filed: 04/21/1978
• Issued: 07/15/1980
• Est. Priority Date: 04/21/1978
• Status: Expired due to Term

• Current Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Inventors: Reis, James J., Robinson, Guner S.
• Primary Examiner(s): Martin, John C.
• Application Number:
  US05/898,970
• Time in Patent Office: 816 Days
• Field of Search: 358/96, 358/162, 358/166, 358/167, 358/37, 340/146 AE
• US Class Current: 348/26
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 5/142 Edging; Contouring

Abstract

A digital machine for detecting and processing pictorial edges in video data. The invention mechanizes, in parallel, three different processing techniques, the outputs of which are combined in a selectable manner to generate processed and enhanced video data. The first parallel processor convolves four inter-related 3×3-element masks with the 2-dimensional video input data to locate the pictorial edges, to determine the edge directions, to execute edge connectivity logic, and to calculate certain edge statistics. The second parallel processor implements a 3×3 element, low or high pass image filter, and an adaptive threshold filter. Both the first and the second parallel processors use Fast-Form algorithms which allow data processing in real time with a minimum of components. The third parallel processor operates on the video data in serial form to generate the video output from the edge processing unit. The third processor is interconnected with the first two processors so as to process and enhance selected features of the serial video data in accord with the outputs from the first two processors.

Claims

1. A system for processing video data in digital form to identify and enhance pictorial edges comprising:

a. window generator means for operating on the input video data for generating digital data in parallel form which represents a sequence of 3×

3 arrays of picture elements, and generating digital data representing a sequence of picture elements at the centers of the 3×

3 arrays,

b. two parallel processing means comprising one parallel processor means for operating on the digital data, which represents the sequence of 3×

3 arrays of picture elements, to identify and locate pictorial edges within the sequence of 3×

3 arrays by means of edge sensitive masks and connectivity requirements, and another parallel processor means for operating on the digital data representing the sequence of center picture elements for introducing a time delay in the data equal to the time delay introduced by the first parallel processing means,

c. enhancer means for receiving the outputs of the two parallel processor means and selectably increasing or decreasing the magnitude or brightness of the center picture elements as represented by the digital data output from the second of the two parallel processor means, in response to the output from the first of the two parallel processor means.

4. The system of claims 1 or 2 or 3 and additionally comprising level slicing means for receiving the input video data and expanding in dynamic range selectable ranges of input data and outputting the expanded data to the window generator means.

2. A system for processing video data in digital form to identify and enhance pictorial edges comprising:

a. window generator means for operating on the input video data for generating digital data in parallel form which represents a sequence of 3×

3 arrays of picture elements, and for generating digital data representing a sequence of picture elements at the centers of the 3×

3 arrays,

b. edge convolver means for receiving and convolving the data, which represents the 3×

3 arrays of picture elements, with 3×

3 masks to compute gradients in each of four quantized directions,

c. edge vector generator means for logically operating on the output of the edge convolver means for generating edge vector data describing the edge angle, the absolute value of the gradient, and the average of the absolute magnitudes of the gradients in the quantized directions,

d. data gate and direction selector means for operating on the output of the edge vector generator means for selecting and passing edge data corresponding to selectable edge directions,

e. connectivity logic tester means for logically operating on the data from the edge vector generator means, which data corresponds to adjacent picture elements, for determining the existence of connected pictorial edges and generating digital data representing the existence or absence of such connected edges,

f. image filter means for operating on the output from the window generator means for filtering the data representing the 3×

3 arrays of picture elements through a selectable high or low pass filter,

g. comparer means for comparing the output of the data gate and direction selector means with a fixed threshold and generating an output when the input from the data gate and direction selector means is the greater of the two inputs,

h. first delayer means for delaying in time the output from the comparer means,

i. logical AND means for operating on the output of the connectivity logic tester means and the output of the first delayer means for generating an output in logical accordance with the inputs,

j. first summer means for selectably operating on the data output from the window generator means, which represent the center picture elements, and selectably operating on either the output of the image filter means or the average gradient data output from the edge vector generator means for generating an output which represents the sum of the inputs,

k. second summer means for operating selectably on the output of the first summer means and selectably on the multiplied output from the data gate and direction selector means for generating an output which represents the sum of the inputs,

l. second delayer means for delaying in time the output of the second summer means,

m. enhancer means for receiving the outputs of the logical AND means and the output from the second delayer means and selectably increasing or decreasing the magnitude or brightness of the center picture elements as represented by the digital data output from the second summer means, in response to the output from the logical AND means.

3. The system of claim 2 wherein the edge convolver means and the image filter means are both of the fast-form type.