## 1 Introduction  
Grapes are highly nutritious and flavorful fruit with a long history of cultivation, remaining among the most widely produced fruits globally [1]. They offer numerous health benefits, including antioxidant and anti-inflammatory properties, modulation of gut microbiota, anti-obesity effects, and protective actions on the heart and liver as well as anti-diabetic and anti-cancer activities [2]. Beyond their consumption as fresh fruit, grapes have extensive applications in the food industry, contributing to products such as wine, grape juice, jams, raisins, and other derivatives [2, 3]. [PERSON] et al. categorized the phenology of the grapevine seasonal cycle into seven principal growth stages: budburst, leaf development, the appearance of inflorescences, flowering, fruit development, fruit maturation, and senescence [4]. [PERSON] proposed an alternative classification of the main grapevine growth stages, including budburst, shoots 10 cm, flowering begins, full bloom, setting, berries pea size, veraison, and harvest [5]. Regardless of the specific classification scheme, chlorophyll plays an indispensable role throughout the entire growth process of grapevines. Chlorophyll is a group of green pigments found in higher plants and other photosynthetic organisms. Among the various types of chlorophyll, _chlorophyll a_ and _chlorophyll b_are the main components, which are essential for the photosynthetic apparatus in terrestrial plants and green algae [6]. A deficiency in chlorophyll can result in leaf yellowing, poor growth and development, and reduced yield. As a fruit-bearing plant, grapevines require adequate chlorophyll to ensure normal growth and development. Changes in the chlorophyll content of grape leaves can also serve as a physiological index for responses and adaptation to UV-C radiation [7]. Therefore, the rapid, accurate, and efficient detection of chlorophyll content is crucial. Traditional methods for measuring chlorophyll content include spectrophotometry, fluorometry, high-performance liquid chromatography (HPLC), and portable chlorophyll meters [8; 9; 10; 11]. However, these methods have limitations. While spectrophotometry, fluorometry, and HPLC provide accurate measurements, they require destructive sampling and the preservation of samples for laboratory analysis. Portable chlorophyll meters, such as SPAD-502 (Konica Minolta Inc., Tokyo, Japan), CL-01 (Hansat-ech Instruments Ltd., King's Lynn, Norfolk, UK), Dualex Scientific+ (FORCE-A, Orsay, France), and CCM-200 (Opto-Sciences Inc., Tokyo, Japan), allow for non-destructive, low-cost, and low-labor measurements [12]. However, these devices often require multiple measurements to reduce variation, and their results are significantly affected by factors such as plant variety, cultivation practices, and environmental conditions. In recent years, hyperspectral imaging (HSI) technology has been extensively studied and proven to be an effective method for determining chlorophyll content in various plant species, including maize leaves [13], sugar beet [14], lettuce [15], wheat [16], and millet leaves [17]. HSI is capable of capturing multiple images at different wavelengths [18], simultaneously collecting both spatial and spectral data [19]. Compared to standard red, green, blue (RGB) images, HSI provides significantly more information. In agricultural production, hyperspectral remote sensing has been widely applied in crop growth monitoring, health assessment, resource allocation, yield estimation, and disease detection [19]. However, during the acquisition of spectral data, issues such as noise, baseline drift, and scattering can easily arise. Spectral preprocessing can reduce and eliminate the influence of various non-target factors [20], enhancing data quality and improving the accuracy and efficiency of subsequent analysis. [PERSON] et al.