JP4257720B2 - Method and apparatus for measuring outer shape of honeycomb structure - Google Patents

Method and apparatus for measuring outer shape of honeycomb structure Download PDF

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JP4257720B2
JP4257720B2 JP2001071913A JP2001071913A JP4257720B2 JP 4257720 B2 JP4257720 B2 JP 4257720B2 JP 2001071913 A JP2001071913 A JP 2001071913A JP 2001071913 A JP2001071913 A JP 2001071913A JP 4257720 B2 JP4257720 B2 JP 4257720B2
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honeycomb structure
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outer shape
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JP2002267427A (en
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好正 近藤
正好 安井
信也 吉田
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NGK Insulators Ltd
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    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
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    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/956—Inspecting patterns on the surface of objects
    • G01N21/95692—Patterns showing hole parts, e.g. honeycomb filtering structures

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Description

【０００１】
【発明の属する技術分野】
本発明は、ハニカム構造体の外形状を画像処理技術を用いて検査するためのハニカム構造体の外形状測定方法及びその方法を実施する装置に関するものである。
【０００２】
【従来の技術】
ハニカム構造体は、例えばセラミック原料を焼結助材等とともに混合して坏土を得、得られた坏土を口金により押出成形後焼成することで作製される。図５にその一例を示すように、このようにして得られたハニカム構造体５１は、円筒形の外壁５２内に隔壁５３により一端面から他端面まで延びる複数の貫通孔５４を有しており、四辺を隔壁５３で囲まれた最小単位の部分をセルと呼ぶ。
【０００３】
上述したハニカム構造体５１は、装置等に組み込まれて使用される。そのため、ハニカム構造体５１の端面における直径等の外形状を測定する必要がある。従来、上述したハニカム構造体５１の外形状の測定は、ハニカム構造体５１の端面を撮像装置で撮像し、撮像して得た原画像に対しエッジ検出処理等の画像処理を行うことで、実施されていた。すなわち、ハニカム構造体５１の外壁５２の部分では隣接する画素の輝度変化が大きくエッジ状になっているため、エッジ検出処理等の従来から知られている画像処理技術を使用することにより、エッジ位置を検出することで外壁部分の位置を求め、求めた外壁部分の位置に基づき外形状を求めていた。
【０００４】
また、他の例として、エッジ検出処理を行う領域を外壁５２の近傍のみに限定して測定精度を向上させる技術も知られている。図６は従来のハニカム構造体の外形状測定方法のうち画像処理する領域をマスクにより外壁部分近傍に限定する例を説明するためのフローチャートである。図６に従ってその方法を説明すると、まず、ハニカム構造体の端面を撮像して原画像を得る（ステップ５１）。次に、原画像を２値化して２値画像を得る（ステップ５２）。次に、２値画像のうちハニカム構造体の内部を塗り潰し、例えば内部が「１」で外部が「０」のように塗り潰し、マスク画像を得る（ステップ５３）。次に、得られたマスク画像の外壁部分言い換えると「１」と「０」との境界を、ハニカム構造体の端面において径方向に例えば１５画素分膨張させた膨張マスク画像を得る（ステップ５４）とともに、ハニカム構造体の端面において径方向に例えば１５画素分縮退させた縮退マスク画像を得る（ステップ５５）。次に、得られた膨張マスク画像と縮退マスク画像との差をとり、膨張マスク画像の外壁部分と縮退マスク画像の外壁部分との間をエッジ検出処理をすべきエッジ検出領域として求める（ステップ５６）。そして、原画像のうち求めたエッジ検出領域に対応する部分に対しエッジ検出処理を行い、原画像のエッジ検出領域内に存在するエッジを検出し、画像上の位置情報（ｘ（ｉ）、ｙ（ｉ）で定義される）としてエッジの位置を外壁の位置として求め、種々の外形状例えば直径を求める。
【０００５】
【発明が解決しようとする課題】
しかしながら、上述した従来のハニカム構造体の外形状測定方法に従って外形状を測定すると、測定結果に測定対象の外形状とは関係のない規則性を伴った凹凸が出る問題が発生した。図７（ａ）、（ｂ）はそれぞれ直径１００ｍｍのハニカム構造体の端面における測定結果を示すグラフである。その誤差の大きさは原画像において最大で１画素分にも相当するもので、測定精度を悪化させる原因となっていた。
【０００６】
本発明の目的は上述した課題を解消して、測定精度を向上させることのできるハニカム構造体の外形状測定方法及び装置を提供しようとするものである。
【０００７】
【課題を解決するための手段】
本発明のハニカム構造体の外形状測定方法は、ハニカム構造体の端面を撮像して原画像 を求め、求めた原画像中におけるハニカム構造体の外壁部分の平均輝度を以下の工程により求め、原画像を２値化して２値画像を求め、求めた２値画像上でハニカム構造体の内部を塗り潰してマスク画像を求め、求めたマスク画像に対し、ハニカム構造体の外壁部分を、一定の割合で膨張させた膨張マスク画像と、一定の割合で縮退させた縮退マスク画像とを求め、求めた膨張マスク画像の外壁部分と縮退マスク画像の外壁部分との間を平均輝度を算出すべき外壁領域とする外壁領域マスク画像を求め、原画像に求めた外壁領域マスク画像をマスクして、原画像のうち外壁部分を含む外壁領域内の画素の平均から平均輝度を求め、縮退マスク画像の内部を、求めた平均輝度の階調で塗り潰した塗り潰し画像を求め、求めた塗り潰し画像に対しエッジ検出処理をすることにより、求めたエッジの位置を外壁の位置として、外形状を測定することを特徴とするものである。
【０００８】
本発明者らが上記従来の課題を検討したところ、測定精度悪化に影響しているのは検出しようとしているエッジ部の内側がセル構造になっていることに起因することが明らかになってきた。一般的な測定においては内部が一様な明るさをもった領域であるが、ハニカム構造体では内部の大部分が暗いセル部であり、これがエッジ部検出に悪影響を及ぼしている。本発明では、ハニカム構造体の内部を外壁部分の平均輝度の階調で塗り潰すことで、エッジ検出処理をする際の外壁部分以外の部分の影響、特に、外壁部分とは輝度が大きく異なるハニカム構造体内部のセル部分の影響をなくすことができ、エッジ検出を精度良く実施することができる。その結果、ハニカム構造体の外形状測定における測定精度を向上させることができる。
【０００９】
本発明の好適な実施態様としては、塗り潰し画像のうち、外壁部分周辺の外壁部分を含むリング状の領域の領域抽出画像に対しエッジ検出処理を行う事がある。この場合は、外壁部分以外の部分の影響をさらに少なくすることができるため好ましい。
【００１０】
また、外壁部分の平均輝度の算出を、原画像を２値化して２値画像を求め、求めた２値画像上でハニカム構造体の内部を塗り潰してマスク画像を求め、求めたマスク画像に対し、ハニカム構造体の外壁部分を、一定の割合で膨張させた膨張マスク画像と、一定の割合で縮退させた縮退マスク画像とを求め、求めた膨張マスク画像の外壁部分と縮退マスク画像の外壁部分との間を平均輝度を算出すべき外壁領域とする外壁領域マスク画像を求め、原画像に求めた外壁領域マスク画像をマスクして、原画像のうち外壁部分を含む外壁領域内の画素の平均から平均輝度を求めることがある。この場合は、外壁部分の平均輝度の算出を精度良く実施することができるため好ましい。
【００１１】
本発明のハニカム構造体の外形状測定装置は、上述したハニカム構造体の外形状測定方法を実施するための装置であって、ハニカム構造体の端面を撮像するための撮像装置と、撮像装置で撮像した端面の原画像を画像処理してハニカム構造体の外形状を測定するための画像処理装置とを備えることを特徴とするものである。本発明の外形状測定装置では、上述したハニカム構造体の外形状測定方法を好適に実施することができる。
【００１２】
本発明の装置の好適な実施態様としては、撮像装置が、ＣＣＤカメラとテレセントリックレンズとから構成される。この場合は、原画像の品質を高くすることができ、結果として測定精度を向上させることができるため好ましい。
【００１３】
【発明の実施の形態】
図１は本発明のハニカム構造体の外形状測定方法を実施する装置の一例の構成を示す図である。図１に示す例において、本発明の外形状測定装置は、基台１上のハニカム構造体２の端面を撮像するための撮像装置３と、撮像装置３で撮像した端面の原画像を画像処理してハニカム構造体２の外形状を測定するための画像処理装置４とを備えている。撮像装置３は、ＣＣＤカメラ１１とレンズに垂直に入射する光のみを取り込むテレセントリックレンズ１２とを組み合わせて構成されている。なお、１３は照明である。また、画像処理装置４は、画像処理ボード２１を備えるパーソナル・コンピュータ２２と画像処理の状況を表示する表示装置２３とから構成されている。ハニカム構造体２の構成は従来例と同様である。
【００１４】
図２は本発明のハニカム構造体の外形状測定方法の一例を説明するためのフローチャートである。以下、図２に示すフローチャートに従って本発明のハニカム構造体の外形状測定方法を説明する。
【００１５】
まず、図２においてステップ１〜ステップ６により従来と同様にエッジ検出処理を行う外壁近傍のリング状のエッジ検出領域を抽出する。すなわち、まず、ハニカム構造体の端面を撮像して原画像を得る（ステップ１）。次に、原画像を２値化して２値画像を得る（ステップ２）。次に、２値画像のうちハニカム構造体の内部を塗り潰し、例えば内部が「１」で外部が「０」のように塗り潰し、マスク画像を得る（ステップ３）。次に、得られたマスク画像の外壁部分言い換えると「１」と「０」との境界を、ハニカム構造体の端面において径方向に例えば１５画素分膨張させた膨張マスク画像（１）を得る（ステップ４）とともに、ハニカム構造体の端面において径方向に例えば１５画素分縮退させた縮退マスク画像（１）を得る（ステップ５）。次に、得られた膨張マスク画像（１）と縮退マスク画像（１）との差をとり、膨張マスク画像（１）の外壁部分と縮退マスク画像（１）の外壁部分との間の領域をエッジ検出処理をすべきエッジ検出領域として求める（ステップ６）。
【００１６】
次に、図２においてステップ７〜ステップ１２によりハニカム構造体の内部を外壁部分の平均輝度の階調に塗り潰した画像を得る。すなわち、まず、ステップ３で得られたマスク画像の外壁部分を、ハニカム構造体の端面において径方向に一定の画素分例えば１．５画素分膨張させた膨張マスク画像（２）を得る（ステップ７）とともに、ハニカム構造体の端面において径方向に一定の画素分例えば２．５画素分縮退させた縮退マスク画像（２）を得る（ステップ８）。
【００１７】
ここで、膨張マスク画像（２）の膨張量及び縮退マスク画像（２）の縮退量は、ステップ４の膨張マスク画像（１）の膨張量及びステップ５の縮退マスク画像（１）の縮退量に比べ、それぞれ大幅に少ない。これは、膨張マスク画像（１）と縮退マスク画像（１）とから求めるエッジ検出領域は例えば３×３とか５×５の微分オペレータを使用するためある程度の幅が必要なのに対し、膨張マスク画像（２）と縮退マスク画像（２）とから求める、外壁部分の平均輝度を求める際に使用する領域の幅は、外壁の幅とほぼ同じ程度である必要があり、外壁部分の幅である数画素の幅に対応させる必要があるためである。これらのエッジ検出領域及び外壁部分の平均輝度を求める際に使用する領域の設定、すなわち、それぞれの膨張量及び縮退量の設定は、個々のハニカム構造体の形状に合わせてその幅を設定する必要がある。
【００１８】
次に、膨張マスク画像（２）と縮退マスク画像（２）との差をとり、膨張マスク画像（２）の外壁部分と縮退マスク画像（２）の外壁部分との間の領域を外壁輝度算出領域として求める（ステップ９）。次に、ステップ１の原画像のうち求めた外壁輝度算出領域に対応する部分に対し平均輝度Ｂａｖｅを算出する（ステップ１０）。次に、ステップ８で求めた縮退マスク画像（２）の内部を平均輝度Ｂａｖｅに対応する階調（例えば原画像が０〜２５５の階調であれば、そのうちの平均輝度Ｂａｖｅが対応するいずれかの階調）で塗り潰し、内部以外の部分を０（０〜２５５のうちの０階調）とした、塗り潰し用画像を求める（ステップ１１）。次に、ステップ１の原画像とステップ１１の塗り潰し用画像との比較を各画素毎に行い、階調の大きい方を選択し、処理後画像を求める（ステップ１２）。
【００１９】
そして、ステップ１２で求めた処理後画像のうち、ステップ６で求めたエッジ検出領域に対応する部分に対しエッジ検出処理を行い、処理後画像のエッジ検出領域内に存在するエッジを検出し、画像上の位置情報（ｘ（ｉ）、ｙ（ｉ）で定義される）としてエッジの位置を外壁の位置として求め、種々の外形状例えば直径を求める。
【００２０】
なお、上述した実施例において、ステップ１〜ステップ６のエッジ検出処理は必須ではなく、内部をＢａｖｅで塗り潰した全画像に対してエッジ検出処理を行っても良い。
【００２１】
また、上述した本発明のハニカム構造体の外形状測定方法の各ステップのうち、図３にステップ１の原画像の例とその明暗の等高線図を示すとともに、図４にステップ１１の塗り潰し用画像の例とその明暗の等高線図を示す。
【００２２】
【発明の効果】
以上の説明から明らかなように、本発明によれば、ハニカム構造体の内部を外壁部分の平均輝度の階調で塗り潰しているため、エッジ検出処理をする際の外壁部分以外の部分の影響、特に、外壁部分とは輝度が大きく異なるハニカム構造体内部のセル部分の影響をなくすことができる。また、塗潰しは外壁のわずかに内側にとどめ、かつ外壁平均輝度より明るい部分は塗潰さないため、外壁の画像情報を傷つけることがなく、エッジ検出を精度良く実施することができる。結果、ハニカム構造体の外形状測定における測定精度を向上させることができる。
【図面の簡単な説明】
【図１】本発明のハニカム構造体の外形状測定方法を実施する装置の一例の構成を示す図である。
【図２】本発明のハニカム構造体の外形状測定方法の一例を説明するためのフローチャートである。
【図３】図２のフローチャートにおけるステップ１の原画像の例とその明暗の等高線図を示す図である。
【図４】図２のフローチャートにおけるステップ１１の塗り潰し用画像の例とその明暗の等高線図を示す図である。
【図５】ハニカム構造体の一例の構成を示す図である。
【図６】従来のハニカム構造体の外形状測定方法のうち画像処理する領域をマスクにより外壁部分近傍に限定する例を説明するためのフローチャートである。
【図７】（ａ）、（ｂ）はそれぞれ従来方法における直径１００ｍｍのハニカム構造体の端面における測定結果を示すグラフであり、（ｂ）では誤差を100倍に強調し表示している。
【符号の説明】
１ 基台、２ ハニカム構造体、３ 撮像装置、４ 画像処理装置、１１ ＣＣＤカメラ、１２ テレセントリックレンズ、１３ 照明、２１ 画像処理ボード、２２ パーソナル・コンピュータ、２３ 表示装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring an outer shape of a honeycomb structure for inspecting the outer shape of the honeycomb structure using an image processing technique, and an apparatus for performing the method.
[0002]
[Prior art]
The honeycomb structure is produced, for example, by mixing a ceramic raw material together with a sintering aid or the like to obtain a kneaded material, and extruding the obtained kneaded material with a die and firing it. As shown in FIG. 5 as an example, the honeycomb structure 51 obtained in this way has a plurality of through holes 54 extending from one end face to the other end face by a partition wall 53 in a cylindrical outer wall 52. The portion of the smallest unit surrounded by the partition walls 53 on all four sides is called a cell.
[0003]
The honeycomb structure 51 described above is used by being incorporated in an apparatus or the like. Therefore, it is necessary to measure the outer shape such as the diameter at the end face of the honeycomb structure 51. Conventionally, the measurement of the outer shape of the honeycomb structure 51 described above is performed by imaging the end face of the honeycomb structure 51 with an imaging device and performing image processing such as edge detection processing on the original image obtained by imaging. It had been. That is, in the outer wall 52 portion of the honeycomb structure 51, the luminance change of adjacent pixels is greatly edged, so that the edge position can be determined by using a conventionally known image processing technique such as edge detection processing. The position of the outer wall portion is obtained by detecting the position, and the outer shape is obtained based on the obtained position of the outer wall portion.
[0004]
As another example, a technique for improving the measurement accuracy by limiting an edge detection processing region only to the vicinity of the outer wall 52 is also known. FIG. 6 is a flowchart for explaining an example of a conventional method for measuring the outer shape of a honeycomb structure in which a region to be image-processed is limited to the vicinity of an outer wall portion by using a mask. The method will be described with reference to FIG. 6. First, an end face of the honeycomb structure is imaged to obtain an original image (step 51). Next, the original image is binarized to obtain a binary image (step 52). Next, the inside of the honeycomb structure is filled in the binary image, for example, the inside is “1” and the outside is “0” to obtain a mask image (step 53). Next, an outer wall portion of the obtained mask image, in other words, an expanded mask image obtained by expanding the boundary between “1” and “0” by, for example, 15 pixels in the radial direction on the end face of the honeycomb structure (step 54). At the same time, a degenerated mask image is generated that is degenerated, for example, by 15 pixels in the radial direction on the end face of the honeycomb structure (step 55). Next, a difference between the obtained expansion mask image and the degenerated mask image is calculated, and an area between the outer wall portion of the expanded mask image and the outer wall portion of the degenerated mask image is obtained as an edge detection region to be subjected to edge detection processing (step 56). ). Then, edge detection processing is performed on a portion corresponding to the obtained edge detection area in the original image, an edge existing in the edge detection area of the original image is detected, and position information (x (i), y on the image) is detected. The position of the edge is determined as the position of the outer wall as defined in (i)), and various outer shapes such as diameters are determined.
[0005]
[Problems to be solved by the invention]
However, when the outer shape is measured according to the above-described conventional method for measuring the outer shape of a honeycomb structure, there is a problem in that the measurement result has irregularities with regularity unrelated to the outer shape to be measured. FIGS. 7A and 7B are graphs showing measurement results on the end face of a honeycomb structure having a diameter of 100 mm. The magnitude of the error corresponds to a maximum of one pixel in the original image, which causes the measurement accuracy to deteriorate.
[0006]
An object of the present invention is to provide a method and apparatus for measuring the outer shape of a honeycomb structure that can solve the above-described problems and improve the measurement accuracy.
[0007]
[Means for Solving the Problems]
Outer shape measuring method of the honeycomb structure of the present invention, the end face of the honeycomb structure by imaging seeking an original image is obtained by the following steps an average luminance of the outer wall portion of the honeycomb structure in the obtained original image, the original The image is binarized to obtain a binary image, the inside of the honeycomb structure is filled on the obtained binary image to obtain a mask image, and the outer wall portion of the honeycomb structure is fixed to the obtained mask image at a certain ratio. An outer wall region in which an expansion mask image expanded at step S and a degenerated mask image reduced by a certain ratio are obtained, and an average luminance is calculated between the outer wall portion of the obtained expansion mask image and the outer wall portion of the degeneration mask image. The outer wall area mask image is obtained, masked the outer wall area mask image obtained in the original image, the average luminance is obtained from the average of the pixels in the outer wall area including the outer wall portion of the original image, and the inside of the degenerated mask image is obtained. A feature is characterized in that an outer shape is measured with a position of the obtained edge as the position of the outer wall by obtaining a filled image filled with the calculated average luminance gradation and performing edge detection processing on the obtained filled image. To do.
[0008]
When the present inventors examined the above-mentioned conventional problems, it has become clear that the influence on the measurement accuracy deterioration is due to the fact that the inside of the edge portion to be detected has a cell structure. . In general measurement, the inside is a region having uniform brightness, but in the honeycomb structure, most of the inside is a dark cell portion, which adversely affects edge detection. In the present invention, the inside of the honeycomb structure is filled with the gradation of the average brightness of the outer wall portion, thereby affecting the influence of the portion other than the outer wall portion when performing edge detection processing, in particular, the honeycomb having a brightness greatly different from that of the outer wall portion. The influence of the cell portion inside the structure can be eliminated, and edge detection can be performed with high accuracy. As a result, the measurement accuracy in measuring the outer shape of the honeycomb structure can be improved.
[0009]
As a preferred embodiment of the present invention, edge detection processing may be performed on a region-extracted image of a ring-shaped region including the outer wall portion around the outer wall portion in the filled image. In this case, the influence of portions other than the outer wall portion can be further reduced, which is preferable.
[0010]
In addition, the average luminance of the outer wall portion is calculated by binarizing the original image to obtain a binary image, and filling the inside of the honeycomb structure on the obtained binary image to obtain a mask image. Then, an expansion mask image obtained by expanding the outer wall portion of the honeycomb structure at a certain rate and a degeneration mask image degenerated at a certain rate are obtained, and the outer wall portion of the obtained expansion mask image and the outer wall portion of the degeneration mask image are obtained. The outer wall area mask image with the outer wall area for which the average luminance is to be calculated is obtained, the outer wall area mask image obtained by masking the original image is masked, and the average of the pixels in the outer wall area including the outer wall portion of the original image The average brightness may be obtained from This is preferable because the average luminance of the outer wall portion can be calculated with high accuracy.
[0011]
A honeycomb structure outer shape measuring apparatus of the present invention is an apparatus for carrying out the above-described honeycomb structure outer shape measuring method, and includes an imaging device for imaging an end face of a honeycomb structure, and an imaging device. And an image processing device for measuring the outer shape of the honeycomb structure by performing image processing on the captured original image of the end face. In the outer shape measuring apparatus of the present invention, the above-described method for measuring the outer shape of the honeycomb structure can be suitably implemented.
[0012]
As a preferred embodiment of the apparatus of the present invention, the imaging apparatus is composed of a CCD camera and a telecentric lens. In this case, the quality of the original image can be improved, and as a result, the measurement accuracy can be improved, which is preferable.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a view showing the configuration of an example of an apparatus for carrying out the method for measuring the outer shape of a honeycomb structure of the present invention. In the example shown in FIG. 1, the outer shape measuring device of the present invention performs image processing on an imaging device 3 for imaging an end face of a honeycomb structure 2 on a base 1 and an original image of the end face taken by the imaging device 3. And an image processing device 4 for measuring the outer shape of the honeycomb structure 2. The imaging device 3 is configured by combining a CCD camera 11 and a telecentric lens 12 that captures only light that enters the lens perpendicularly. Reference numeral 13 denotes illumination. The image processing apparatus 4 includes a personal computer 22 including an image processing board 21 and a display device 23 that displays the status of image processing. The structure of the honeycomb structure 2 is the same as that of the conventional example.
[0014]
FIG. 2 is a flowchart for explaining an example of a method for measuring the outer shape of the honeycomb structure of the present invention. Hereinafter, the method for measuring the outer shape of the honeycomb structure of the present invention will be described with reference to the flowchart shown in FIG.
[0015]
First, in step 1 to step 6 in FIG. 2, a ring-shaped edge detection region in the vicinity of the outer wall where edge detection processing is performed as in the conventional case is extracted. That is, first, an end face of the honeycomb structure is imaged to obtain an original image (step 1). Next, the original image is binarized to obtain a binary image (step 2). Next, the inside of the honeycomb structure is filled in the binary image, for example, the inside is “1” and the outside is “0” to obtain a mask image (step 3). Next, an expanded mask image (1) is obtained in which the boundary between the outer wall portion of the obtained mask image, in other words, the boundary between “1” and “0” is expanded by, for example, 15 pixels in the radial direction on the end face of the honeycomb structure ( Along with step 4), a degenerated mask image (1) degenerated, for example, by 15 pixels in the radial direction on the end face of the honeycomb structure is obtained (step 5). Next, the difference between the obtained expansion mask image (1) and the degenerated mask image (1) is taken, and an area between the outer wall portion of the expanded mask image (1) and the outer wall portion of the degenerated mask image (1) is obtained. An edge detection area to be subjected to edge detection processing is obtained (step 6).
[0016]
Next, in FIG. 2, an image in which the inside of the honeycomb structure is filled with the gradation of the average brightness of the outer wall portion by Step 7 to Step 12 is obtained. That is, first, an expanded mask image (2) is obtained by expanding the outer wall portion of the mask image obtained in step 3 by a certain number of pixels, for example, 1.5 pixels in the radial direction on the end face of the honeycomb structure (step 7). ) And a degenerated mask image (2) degenerated by a certain number of pixels in the radial direction, for example, 2.5 pixels, is obtained on the end face of the honeycomb structure (step 8).
[0017]
Here, the expansion amount of the expansion mask image (2) and the reduction amount of the degeneration mask image (2) are the expansion amount of the expansion mask image (1) in step 4 and the degeneration amount of the degeneration mask image (1) in step 5. Each is significantly less. This is because the edge detection region obtained from the dilated mask image (1) and the degenerate mask image (1) requires a certain width because, for example, a 3 × 3 or 5 × 5 differential operator is used, whereas the dilated mask image ( The width of the area used when obtaining the average luminance of the outer wall portion obtained from 2) and the degenerate mask image (2) needs to be approximately the same as the width of the outer wall, and several pixels which are the width of the outer wall portion This is because it is necessary to correspond to the width of. These edge detection areas and areas used to determine the average brightness of the outer wall portion, that is, the respective expansion amounts and degeneration amounts must be set according to the shape of the individual honeycomb structure. There is.
[0018]
Next, the difference between the dilated mask image (2) and the degenerated mask image (2) is taken, and the area between the outer wall portion of the dilated mask image (2) and the outer wall portion of the degenerated mask image (2) is calculated as the outer wall luminance. As a region (step 9). Next, the average luminance Bave is calculated for the portion corresponding to the obtained outer wall luminance calculation region in the original image in step 1 (step 10). Next, in the reduced mask image (2) obtained in step 8, the gradation corresponding to the average luminance Bave (for example, if the original image has a gradation of 0 to 255, one of the average luminances Bave corresponding thereto) The image for filling is obtained by filling the area other than the inside with 0 (0 gradation of 0 to 255) (step 11). Next, the original image in step 1 and the image for filling in step 11 are compared for each pixel, the one with the larger gradation is selected, and the processed image is obtained (step 12).
[0019]
Then, edge detection processing is performed on the portion corresponding to the edge detection area obtained in step 6 from the processed image obtained in step 12, and edges existing in the edge detection area of the processed image are detected. As the upper position information (defined by x (i) and y (i)), the position of the edge is obtained as the position of the outer wall, and various outer shapes such as diameters are obtained.
[0020]
In the above-described embodiment, the edge detection processing in steps 1 to 6 is not essential, and the edge detection processing may be performed on all images in which the inside is filled with Bave.
[0021]
Among the steps of the above-described method for measuring the outer shape of the honeycomb structure of the present invention, FIG. 3 shows an example of the original image of Step 1 and its contour map, and FIG. 4 shows the image for filling in Step 11. And an example of its contour map.
[0022]
【The invention's effect】
As is clear from the above description, according to the present invention, the inside of the honeycomb structure is filled with the gradation of the average luminance of the outer wall portion, so the influence of the portion other than the outer wall portion when performing edge detection processing, In particular, it is possible to eliminate the influence of the cell portion inside the honeycomb structure that has a luminance that is significantly different from that of the outer wall portion. In addition, the painting is limited to the inside of the outer wall and the portion brighter than the average luminance of the outer wall is not painted, so that the edge detection can be performed accurately without damaging the image information on the outer wall. As a result, the measurement accuracy in measuring the outer shape of the honeycomb structure can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an example of an apparatus for carrying out a method for measuring an outer shape of a honeycomb structure of the present invention.
Fig. 2 is a flowchart for explaining an example of a method for measuring an outer shape of a honeycomb structure according to the present invention.
FIG. 3 is a diagram showing an example of an original image in step 1 in the flowchart of FIG. 2 and its contour map.
FIG. 4 is a diagram showing an example of an image for filling in step 11 in the flowchart of FIG. 2 and its contour map.
Fig. 5 is a diagram showing a configuration of an example of a honeycomb structure.
FIG. 6 is a flowchart for explaining an example in which a region for image processing is limited to the vicinity of an outer wall portion by using a mask in a conventional method for measuring the outer shape of a honeycomb structure.
FIGS. 7A and 7B are graphs showing measurement results on the end face of a honeycomb structure having a diameter of 100 mm according to the conventional method, respectively, and FIG. 7B shows the error highlighted 100 times.
[Explanation of symbols]
1 base, 2 honeycomb structure, 3 imaging device, 4 image processing device, 11 CCD camera, 12 telecentric lens, 13 illumination, 21 image processing board, 22 personal computer, 23 display device

Claims (4)

ハニカム構造体の端面を撮像して原画像を求め、
求めた原画像中におけるハニカム構造体の外壁部分の平均輝度を以下の工程により求め、
原画像を２値化して２値画像を求め、
求めた２値画像上でハニカム構造体の内部を塗り潰してマスク画像を求め、
求めたマスク画像に対し、ハニカム構造体の外壁部分を、一定の割合で膨張させ
た膨張マスク画像と、一定の割合で縮退させた縮退マスク画像とを求め、
求めた膨張マスク画像の外壁部分と縮退マスク画像の外壁部分との間を平均輝度
を算出すべき外壁領域とする外壁領域マスク画像を求め、
原画像に求めた外壁領域マスク画像をマスクして、原画像のうち外壁部分を含む
外壁領域内の画素の平均から平均輝度を求め、
縮退マスク画像の内部を、求めた平均輝度の階調で塗り潰した塗り潰し画像を求め、
求めた塗り潰し画像に対しエッジ検出処理をすることにより、求めたエッジの位置を外壁の位置として、外形状を測定することを特徴とするハニカム構造体の外形状測定方法。Image the end face of the honeycomb structure to obtain the original image,
Obtain the average brightness of the outer wall portion of the honeycomb structure in the obtained original image by the following steps ,
Obtain a binary image by binarizing the original image,
A mask image is obtained by painting the inside of the honeycomb structure on the obtained binary image,
For the obtained mask image, the outer wall of the honeycomb structure is expanded at a certain rate.
Obtaining a dilated mask image and a degenerated mask image degenerated at a certain rate,
Average brightness between the outer wall part of the obtained expansion mask image and the outer wall part of the degenerate mask image
Obtain the outer wall area mask image as the outer wall area to be calculated,
Mask the outer wall area mask image obtained in the original image, and include the outer wall portion of the original image
Find the average brightness from the average of the pixels in the outer wall area,
Find a filled image in which the inside of the degenerate mask image is filled with the calculated average brightness gradation,
A method for measuring an outer shape of a honeycomb structure , wherein the outer shape is measured by performing an edge detection process on the obtained filled image , with the obtained edge position as the position of the outer wall . 前記塗り潰し画像のうち、外壁部分周辺の外壁部分を含むリング状の領域の領域抽出画像に対しエッジ検出処理を行う請求項１記載のハニカム構造体の外形状測定方法。  The method for measuring an outer shape of a honeycomb structure according to claim 1, wherein edge detection processing is performed on a region-extracted image of a ring-shaped region including an outer wall portion around the outer wall portion in the filled image. 請求項１または２記載のハニカム構造体の外形状測定方法を実施するための装置であって、ハニカム構造体の端面を撮像するための撮像装置と、撮像装置で撮像した端面の原画像を画像処理してハニカム構造体の外形状を測定するための画像処理装置とを備えることを特徴とするハニカム構造体の外形状測定装置。An apparatus for carrying out the method for measuring the outer shape of a honeycomb structure according to claim 1 or 2 , comprising: an imaging device for imaging an end face of the honeycomb structure; and an original image of the end face taken by the imaging apparatus. An apparatus for measuring the outer shape of a honeycomb structure, comprising: an image processing device for processing and measuring the outer shape of the honeycomb structure. 前記撮像装置が、ＣＣＤカメラとテレセントリックレンズとからなる請求項３記載のハニカム構造体の外形状検査装置。4. The honeycomb structure outer shape inspection device according to claim 3 , wherein the imaging device includes a CCD camera and a telecentric lens.
JP2001071913A 2001-03-14 2001-03-14 Method and apparatus for measuring outer shape of honeycomb structure Expired - Lifetime JP4257720B2 (en)

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