US 3,940,557 A · Subtractive image analysis

Abstract

A method and apparatus is described for performing controlled erosion of electrical signals relating to detected features in an image which is scanned. The erosion is performed by counting (in an up or down counter) n timing pulses in each sequence corresponding to a detected signal pulse before an overflow signal indicating that n timing pulses have been received is generated. The overflow signal is used to release subsequent timing pulses which are then analysed by counting. The timing pulses so released correspond to the portion of a detected feature left after erosion from the leading edge. The method is applied parallel, perpendicular and at non-orthogonal angles to the line scan direction. The apparatus required can be minimised by applying down-counting techniques and storing a signal to indicate complete erosion in one direction instead of recirculating large quantities of information from line to line. An overflow signal indicating that erosion has been successfully completed in a second subsequent direction together with the indicator signal from a previous erosion is used to instigate another direction of erosion or to release an output pulse for counting.

Claims24

Dependent claims

A method of analysing a feature in a field comprising:

converting the video signal amplitude excursions to constant amplitude pulses by threshold detection;
releasing a series of timing pulses for the duration of each constant amplitude pulse and counting each series of timing pulses so released;
resetting the counting circuit in the absence of a timing pulse during a timing interval;
generating an overflow signal when the counter reaches a value n;
releasing timing pulses for the duration of each overflow signal so generated;
and
analysing the timing pulses so released.

4 more elements

A method of analysing a feature in a field comprising the steps of:

scanning the field to produce a video signal;
converting the video signal amplitude excusions to constant amplitude pulses by threshold detection;
generating constant frequency timing pulses;
sampling the signal made up of the constant amplitude pulses K times during each line scan by K equally spaced apart signals derived from the timing pulses occurring during this line scan, generating an electrical signal corresponding to a numerical value N, inserting the generated signal into an electrical store having at least K series locations;
operating the electrical store in synchronism with the timing pulses to shift signals therein from one location to the next so that the signals therein are caused to appear in turn at the output thereof during each line scan;
reducing by one the numerical value of the signal in the output of the store and transferring this reduced value signal to the store input for recirculation;
comparing the reduced value signal with a programmed value;
generating a first output signal pulse whenever the signal transferred to the input of the store is zero;
counting all such first output signal pulses;
generating in response to a detected zero signal condition a signal corresponding to one;
and
inserting the signal having a numerical value of one into the store in place of the zero condition, so that a zero condition will be produced after reduction by one on the next line scan if an overflow signal is again available at that timing position on the next line scan.

9 more elements

Apparatus for analysing a feature in a field comprising, in combination;

means for forming an image of the field;
means for scanning the field in a series of parallel lines to produce a video signal;
means for threshold detecting the video signal amplitude excursions to produce a signal comprised of constant amplitude pulses;
means for gating the signal comprised of constant amplitude pulses at regular intervals along each line scan thereby to produce a series of timing pulses for the duration of each constant amplitude pulse;
means for counting timing pulses so released;
means for resetting the counting circuit in the absence of a timing pulse during the timing interval between timing pulses;
means for generating an overflow signal when the counter reaches a value n;
means for releasing timing pulses for the duration of each overflow signal so generated;
and
means for analysing the timing pulses so released.

7 more elements

Apparatus for analysing a feature in a field comprising;

means for forming an image of the field;
means for scanning the field in a series of parallel lines to produce a video signal;
means for threshold detecting the video signal amplitude excursions to produce a signal comprised of constant amplitude pluses;
means for sampling the signal comprised of constant amplitude pulses at regular intervals during each line scan to produce a series of timing pulses for the duration of each constant amplitude pulse;
counting means for receiving timing pulses released during each such constant amplitude pulse;
means for generating a signal corresponding to a programmed numerical value N;
means for inserting the generated electrical signal corresponding to N into the counting circuit whenever a timing pulse is not released during a timing interval;
means for reducing the numerical value in the counter by one for each timing pulse supplied to the counter;
means for generating an overflow signal when the numerical value in the counter reaches a programmed value;
means for releasing subsequent timing pulses for the duration of each overflow signal so generated;
and
means for analysing the timing pulses so released.

9 more elements

Dependencies are inferred from the claim text.

Subtractive image analysis

Life of this patent

Subtractive image analysis

Life of this patent

Abstract

Claims24