Su Altı Görüntülerinin CVC Yöntemi Kullanılarak İyileştirilmesi

Year 2023, Volume: 28 Issue: 3, 962 - 972, 29.12.2023

Arda Üstübioğlu , Beste Üstübioğlu

https://doi.org/10.53433/yyufbed.1249102

Abstract

Su altı görüntülerinin, sudan geçen ışığın dalga boyuna bağlı olarak seçici zayıflama sonucunda kontrastı ve görünürlüğü oldukça düşük olmaktadır. Bu sebeple ilgili çalışmada sualtı görüntülerinde görüntü kontrastlarını iyileştirmek amacıyla literatürde ilk kez görüntünün parlaklık özelliklerini RGB uzayında değerlendiren Bağlamsal ve Değişken Kontrast (CVC) tabanlı bir yöntem önerilmiştir. Önerilen yöntem kontrastı iyileştirirken aynı zamanda sualtı görüntüsü üzerinde yerel renk düzeltmesi de yapmaktadır. Literatürde bu alandaki yöntemler kanalların global histogramı üzerinde çeşitli yaklaşımlar uygularken, önerilen yöntem HSV uzayında S ve V kanalındaki görüntüleri örtüşmeyen alt bloklara bölerek histogram eşitleme uygulamaktadır. Nitel analiz sonuçlarına bakıldığında, önerilen yöntemin diğer iyileştirme yöntemlerine kıyasla kontrast, renk ve ayrıntı bakımından çok iyi görüntüler ürettiği görülmektedir. Önerilen yöntem ayrıca çıktı görüntülerindeki mavi-yeşil efektini de azaltmaktadır. Nicel analiz olarak ise önerilen yöntem 200 sualtı görüntüsü için diğer çalışmalar arasında en yüksek ortalama entropi (7.86), EME (40.90), EMEE (32.13) ve Sobel (90982) değerini üretmektedir.

Keywords

Bağlamsal ve değişken kontrast, Entropi, Kontrast sınırlı uyarlanabilir histogram eşitleme

Underwater Image Enhancement using CVC Method

Abstract

Contrast and visibility of underwater images become very low as a result of selective attenuation depending on the wavelength of light passing through the water. For this reason, a CVC-based method, which evaluates the brightness properties of the image in RGB space, is proposed for the first time in the literature to improve image contrasts in underwater images. While the proposed method improves the contrast, it also performs local color correction on the underwater image. While the methods in this field in the literature apply various approaches on the global histogram of the channels, the proposed method divides the images in the S and V channels into non-overlapping sub-blocks in the HSV space and applies histogram equalization to them. The qualitative analysis results show that the proposed method produces very good images in terms of contrast, color and detail compared to other enhancement methods. The proposed method also reduces the blue-green effect in the output image. As for quantitative analysis, the proposed method produces the highest mean entropy (7.86), EME (40.90), EMEE (32.13) and Sobel (90982) values among other studies for 200 underwater images.

Keywords

CVC, CLAHE, Entropy

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