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US 4,790,022 AGranted
Method and apparatus for detecting colored regions, and method and apparatus for articles thereby
AssigneeLockwood Graders (UK) Limited
InventorTimothy J. Dennis
Life of this patent
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Abstract
A method of color detection, in which electrical signals derived from two quantities, preferably orthogonal quantities, for example (R-L) and (B-L) are digitized. A time-shift is applied to the signals, either before or after digitization, and a difference signal is formed between each original signal, and its time-shifted counterpart. The difference signals are then used as a key to a "lookup" table, to provide an output only when specified combinations of the two difference signals are encountered.
Claims21
A method of sorting articles, comprising the steps of:
- inspecting the articles to determine any occurrence of target colours, and
- routing the articles in accordance with the colours detected thereon,
- wherein the articles are inspected by
- scanning the articles using a raster scan technique to develop electrical output signals containing colour information,
- time shafting said electrical output signals to produce time-shifted signals,
- forming the difference between each said electrical output signal and its counterpart time-shifted signal to thereby obtain spatial colour difference signals, and
- applying said spatial colour difference signals to a memory device,
- wherein said memory device has a plurality of storage locations and corresponding address lines allowing access to said storage locations, and wherein information as to target colours is stored in said storage locations,
- and wherein said spatial colour difference signals are applied to said memory device, by way of buffering means, as address signals to the address lines of the memory device to access selected ones of said storage locations,
- and wherein said memory device is arranged to provide an output only when specific combinations of said spatial colour difference signals are applied thereto, said memory device output thereby indicating an occurrence on one of the article of a target colour.
7 more elements
Apparatus for sorting articles comprising:
- an inspection zone,
- a raster scan apparatus arranged to scan articles in said inspection zone and to develop elecltrical output signals containing colour information,
- means for time shifting said electrical output signals to produce time-shifted signals,
- differencing means for receiving said electrical output signals and said time-shifted signals and arranged to form the difference between each electrical output signal and its counterpart time-shifted signal to thereby form spatial colour difference signals,
- a memory device having a plurality of storage locations and corresponding address lines allowing said storage locations to be accessed, information as to target colours being stored in said storage locations,
- buffering means for applying said spatial colour difference signals as address signals to the address lines of said memory device to access selected ones of said storage locations,
- means enabling an output from said memory device only when specific combinations of said spatial colour difference signals are applied there to, said memory device output thereby indicating an occurrence on one of the articles of a target colour, and
- means for routing the said articles in accordance with the colours detected on the articles.
5 more elements
Dependencies are inferred from the claim text.