# A Multi-Step Image Pre-Enhancement Strategy for a Fish Feeding Behavior Analysis Using Efficientnet
## 2 Methodology
### Multi-Step Image Pre-Enhancement Strategy  
As illustrated in Figure 4, a systematic demonstration is provided of the enhancements achieved in underwater photography image quality through the application of  
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**Stage** & **Time** & **Feeding Intensity** & **Definition Behavioral Characteristics** & **Evaluation Criteria** \\ \hline High Intensity & 1–2 min after feeding & Most active chasing and ingesting behavior & Significant splashing and noise on the surface, dense chasing of food by the fish & Rapid decrease in feed, frequent surface activity \\ \hline Medium Intensity & 2–3 min after feeding & Feeding behavior & Fish start to disperse, there is less noise begins to slow but remains active & Slower consumption and splashing on the surface, but still noticeable chasing of food & Slower consumption of feed, some fish still actively feeding \\ \hline Low Intensity & 3–4 min after feeding & Only few fish show feeding behavior as feed decreases further & Most fish start to disperse, and a few active fish occasionally chase remaining feed & Continued observation of few fish feeding behaviors \\ \hline Inactive & More than 4 min after feeding & Most fish no longer actively chase feed, showing low feeding activity & Fish swim slowly in the water, occasionally staying at the bottom, with almost no response to feed & High feed residue, slow and scattered fish behavior \\ \hline \hline \end{tabular}
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Table 1: Formal definition and evaluation criteria for feeding intensity.  
Figure 3: Classification chart of different feeding behavior intensities. (**a**) Strong Feeding: At the initial stage, the fish actively compete for bait, accompanied by splashes and noise, exhibiting a strong desire for feeding. (**b**) Medium Feeding: As the bait begins to diminish, a portion of the fish reduces their feeding activities, resulting in a decrease in overall feeding intensity to a moderate level. (**c**) Weak Feeding: With further reduction in bait, only a few fish continue to show interest in feeding, and the school begins to disperse further, indicating sparse feeding behavior. (**d**) None Feeding: After approximately 4 min, almost all fish lose their desire to feed and start to disperse, swimming slowly along the bottom, signaling the end of the feeding process.  
a multi-step image pre-enhancement strategy. The original image displays a school of fish captured under natural lighting conditions in an underwater environment, affected by surface reflection and an uneven distribution of light. The image processed by the MSRCR algorithm has a reduced impact of surface reflection and, through dynamic range compression and color restoration techniques, an enhanced visual effect and color fidelity. The subsequent mdc processing step optimized the local contrast, particularly enhancing the discernibility of details in regions of low contrast, rendering them more conspicuous. Finally, the application of Unsharp Masking technology improved the local contrast and edge clarity of the image, especially in delineating the boundary between the fish and their background, thereby enhancing the visual resolution. The entire pre-enhancement process not only significantly improved the image quality but also provided clear, enhanced visual information for deeper image analysis and fish behavior recognition without sacrificing color authenticity.