11 1. To understand the function of colour signals in nature, we require robust quantitative 12 analytical frameworks to enable us to estimate how animal and plant colour patterns appear 13 against their natural background as viewed by ecologically relevant species. Due to the 14 quantitative limitations of existing methods, colour and pattern are rarely analysed in 15 conjunction with one another, despite a large body of literature and decades of research on 16 the importance of spatiochromatic colour pattern analyses. Furthermore, key physiological 17 limitations of animal visual systems such as spatial acuity, spectral sensitivities, photoreceptor 18 abundances and receptor noise levels are rarely considered together in colour pattern 19 analyses. 20 2. Here, we present a novel analytical framework, called the 'Quantitative Colour Pattern 21 Analysis' (QCPA). We have overcome many quantitative and qualitative limitations of existing 22 image segmentation, which we call 'Receptor Noise Limited Clustering', used here for the first 30 time. Furthermore, QCPA provides a novel psycho-physiological approach to the modelling of 31 spatial acuity using convolution in the spatial or frequency domains, followed by 'Receptor 32 Noise Limited Ranked Filtering' to eliminate intermediate edge artefacts and recover sharp 33 boundaries following smoothing. We also present a new type of colour pattern analysis, the 34 'Local Edge Intensity Analysis' (LEIA) as well as a range of novel psycho-physiological 35 approaches to the visualisation of spatiochromatic data.36 4. QCPA combines novel and existing pattern analysis frameworks into what we hope is a unified, 37 user-friendly, free and open source toolbox and introduce a range of novel analytical and data-38 visualisation approaches. These analyses and tools have been seamlessly integrated into the 39 MICA toolbox providing a dynamic and user-friendly workflow. 40 5. QCPA is a framework for the empirical investigation of key theories underlying the design, 41 function and evolution of colour patterns in nature. We believe that it is compatible with, but 42 more thorough than, other existing colour pattern analyses. 43 44 Keywords: colour pattern analysis, colour perception, image analysis, visual modelling, receptor noise 45 limited model, animal colouration, colour space 46 47 65