皮革瑕疵檢測以建構扣點標準之研究

Abstract

皮革是原始自然產物，皮面瑕疵無法透過加工完全消除，皮革加工廠在交付產品給下游皮製品工廠時，是由人員依經驗來判別及扣除瑕疵呎數；目前尚未有公認的扣減標準可依循，常造成皮料供應及買賣間的紛爭。本研究廣泛收集瑕疵皮，整理出170片瑕疵樣本皮，參考皮革業者實務經驗，將瑕疵依形狀區分為細點狀、圓點狀、線狀、條狀、破洞、圖案狀、不規則等七類。再運用電腦視覺系統對皮面瑕疵進行自動檢測，自動檢測不明顯者則運用半自動方法對皮面瑕疵影像進行處理、分析，以檢測出皮面不可用面積，並依不可用面積訂出此七類瑕疵之補償扣點標準(每點10㎝2)。最後利用電腦隨機模擬買賣皮革50~1000張，得到運用此扣點標準之不可用面積，與實測不可用面積比較結果其平均誤差為1.16%，差異面積與買賣面積比較其平均差異率為0.05%，可信度甚高。本文之研究結果，應可提供皮革業與皮製品業間，一個可快速計算且可信賴的皮革瑕疵扣減呎碼標準，及作為國家皮革瑕疵應扣減呎碼標準的參考。

Defects exist on natural leather surface. Manufacturing generally cannot eliminate it. No international criterion specifies the compensatory counting for calf leather surface defects. So, complicated negotiation causes additional cost and argument between supplier and purchaser. This paper is to establish a compensatory standard of leather defects area. We start by collecting 170 samples of defective leather and by discussing with the experienced experts, and then classify the leather defects into seven types. By using digital image processing technique, we devise automatic and semi-automatic detective methods to identify the defects. The nearby defects can also grouped into a larger unusable leather region and its pixel number can compute the corresponding unusable area. The compensatory standard corresponding to each type of leather defect is then defined. A practical leather transaction is simulated to evaluate the reliability of the established compensatory standard. The mean error rate between the leather defect deductible area calculated by compensatory standard and the unusable area derived by automatic machine inspection method is 1.16%. The mean deviation rate for the leather area of the simulated transaction is 0.05%. This provides an effective and reliable compensatory standard for finished leather transaction.