Data from: To be seen or to hide: visual characteristics of body patterns for camouflage and communication in the Australian giant cuttlefish, Sepia apama.

It might seem obvious that a camouflaged animal must generally match its background whereas to be conspicuous an organism must differ from the background. However, the image parameters (or statistics) that evaluate the conspicuousness of patterns and textures are seldom well-defined, and animal coloration patterns are rarely compared quantitatively to their respective backgrounds. Here we examine this issue in the Australian giant cuttlefish Sepia apama. We confine our analysis to the best-known and simplest image statistic, the correlation in intensity between neighbouring pixels. S. apama can rapidly change their body patterns from assumed conspicuous signaling to assumed camouflage, thus providing an excellent and unique opportunity to investigate how such patterns differ in a single visual habitat. We describe the intensity variance and spatial frequency power spectra of these differing body patterns, and compare these patterns to the backgrounds against which they are viewed. The measured image statistics of camouflaged animals closely resemble their backgrounds, while signaling animals differ significantly from their backgrounds. Our findings may provide the basis for a set of general rules for crypsis and signals. Furthermore, our methods may be widely applicable to the quantitative study of animal coloration.伪装动物通常需与背景环境保持色彩匹配，而具备显眼信号特征的生物则需与背景形成差异，这一结论看似不言自明。然而，用于评估图案与纹理显眼程度的图像参数（或统计量）往往缺乏明确的定义，且动物体色图案与其对应背景的定量对比研究也极为罕见。本研究以澳大利亚巨型乌贼（Sepia apama）为研究对象，对该问题展开探讨。本次分析仅聚焦于最经典且最简单的图像统计量——相邻像素间的强度相关性。澳大利亚巨型乌贼可快速切换体色图案，从学界普遍认为用于信号传递的显眼状态转为伪装状态，这为探究单一视觉生境下不同体色图案的差异提供了绝佳且独特的研究契机。本研究对这两类不同体色图案的强度方差与空间频率功率谱进行了描述，并将其与观测时所处的背景环境进行对比。测量结果显示，处于伪装状态的乌贼，其图像统计特征与背景高度相似；而处于信号传递状态的乌贼，其图像统计特征则与背景存在显著差异。本研究结果可为构建隐蔽性与信号传递的通用规则体系提供理论基础。此外，本研究采用的方法也可广泛应用于动物体色的定量研究领域。