Agricultural article inspection apparatus and method employing spectral manipulation to enhance detection contrast ratio

Abstract

A sorting system (110) conveys articles, such as peaches (114) on a conveyor belt (112) past an inspection zone (126) that is lighted by an illumination source (90) radiating a number of emission peaks over visible and infrared portions of the spectrum. The illumination source generates the radiation from an Indium Iodide lamp (92) that is reflected off a parabolic reflector (94) and through a "soda straw" collimator (100) to illuminated the peaches. A detector system (118) employs line scanning visible and infrared cameras (142, 140) to sense visible and IR wavelength reflectance values for the peach meat (124) and peach pit or pit fragments (126). Various image processing and analysis methologies, such as subtraction, ratio, logarithmic, regression, combination, angle, distance, and shape may be employed to enhance the image contrast and classify the resulting data for sorting the peaches. Employing subtraction also cancels "glint" caused by specular reflections of the illumination source off the peaches and into the cameras.

Description

[0001] This application is a continuation-in-part of U.S. patent application Ser. No. 09 / 277,568, filed Mar. 26, 1999, for PEACH PIT DETECTION APPARATUS AND METHOD.[0002] This invention relates to agricultural product inspection and more particularly to an apparatus and a method of inspecting peach halves for pits and pit fragments.[0003] A popular agricultural product is canned peach halves, slices and cubes. The peach variety typically used for canning is referred to as a "cling" peach, whereas the popular eating peach variety is referred to as "the free stone" peach, which is not used for canning because they lose their taste during the canning process. The variety names cling and free stone imply the relative ease with which the stone (hereafter "pit") can be removed from the fruit.[0004] Many peach processors employ an Atlas splitting machine to remove the pit. This machine consist of a circumferential knife, that looks and functions much like the iris of a camera lens. As the ...

AI Technical Summary

Benefits of technology

0070] FIG. 12 is a Polaroid photograph taken of a television monitor displaying a two-dimensionally image generated from the video output of the SWIR camera viewing a peach with an embedded pit. The illumination source includes an Induim Iodide arc discharge lamp. The peach was prepared by splitting it with a knife and immersing it in a warm 12 percent sodium hydroxide solution for 30 seconds. This preparation removes a portion of the

Problems solved by technology

Unfortunately, the blade cannot always adequately secure the pit and when the peach halves fall away, the entire pit may stay embedded in one of the halves.

Successful removal of pits from cling peaches presents a considerable agricultural processing challenge.

Unfortunately, the pit color closely matches the color of peach flesh.

Moreover, the inspectors often have to manually detect small "hidden" pit fragments by wiping the tip of their fingers around the cavity left in the peach by a removed pit.

These inspection difficulties have previously ruled out automatically inspecting peach halves with machine vision techniques that detect visual wavelengths of light because the close color match between peach flesh and pits and the hidden nature of many pit fragments would rend

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