Research Methodology
Chapter 4: Data Collection
2. Physical structure (Design)
4.6.4 Color palette generator using K-means clustering algorithm
For visual analysis, tools such as Image J (Rasband, 2011) and machine learning algorithm (K-means) were used, while for statistical analysis, Microsoft excel (2011) was utilized.
Descriptions of following elements are given as follows
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Image Colour Map Colour pallate
Fig. 4.67: Overview of color palette generation of a Xorai with Bhagvad (Illustration: Researcher)
Color palette (fig. 4.67) is an essential output of color quantization process. Color palette provides information on the dominant list of colors of any particular image. The color palette has been used effectively by various researchers in field of image processing and designs (Meier et al., 2004; Tsai et al., 2004; Ke et al., 2006; Heer and Stone, 2012).
In this study, an open source program (Mediafox Marketing, 2015) “Color palette generator” was adopted for color palette quantification of various design elements of Naamghar. This open source program is available online, which is based on “Lloyd’s k- means clustering algorithm (Linde et al., 1980). The proposed algorithm was actually used for pattern recognition (Tou and Gonzalez, 1974). It is a sub-optimal quantization approach which can be additionally applied to image segmentation, color vision and vector quantization (Hu and Lee, 2007). The color palette is generated in two stages using K- means algorithm. The stages involve pixel grouping process and the centroid updating process. Through iterative process involving these two stages, the desired color palette is obtained.
The tool allows generating color palette of the collected visual images of various interior and exterior design elements of Naamghar. The procedure for generating color palette is as follows. The high-resolution image of the particular element that needs to be analysed is first selected. Initial editing is carried out on the image to remove any unwanted background color or elements that appear in the image. The edited image containing that particular element is then imported in the program for generating color palette. The color palette generated from this program contains actual image, color palette image as well as list of dominant colors along with their proportion (in %). The adopted process is similar to the one adopted by Delon et al. (2005) and Chang et al. (2015).
Fig. 4.68 shows the sample image along with colored palette and list of colors in proportion obtained for element “Xorai with Bhagvad” Avatar from a particular Naamghar. As seen from the figure, the color palette obtained contains different forms of Red oxide, Au chio, copper rose, Mckenzie and muddy waters with their proportions as 44%, 24% 13% 8% 7% and 4% respectively. This suggests that the most dominant color in this element is red oxide while least is muddy waters. The color palette obtained hence can be useful to provide comparative study on changes in design of various elements across space (urban, semi-urban and rural) and time (age of establishment).
b) Image analysis using Image J
(a) (b)
(c) (d)
(e) (f)
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Fig. 4.68: Image analysis using Image J. Overview of (a) Color image of Narsimha and (b) Binary image of Narsimha for calculation of area. Similarly, overview of color images of (c) Varah (one of dashavatara) ;(e)
Vishnu and their respective binary images is shown in (d) and (f) (Illustration: Researcher)
c) Study of Colour palette variation i. Main Gate Naamghar:
Main gate has been analyzed in terms of its modification in the colour used into it.
Visual documentation is been done and further color analysis of each and every main gate has been done for 26 Naamghars with an online colour analysis tool (called colours). One can see in Fig. 4.69 (a) and (b) the depiction of variations in colours like granite grey, old lavender etc. on the main gate colour palette of Barpeta Satra.
Naamghar has been chosen from 14th to 20th century and when its been compared it has been found that modification in the use of colour has happened. Naamghars between 14th and 15th century [Fig. 4.69 (b)] has more of grey pallet moving towards bright use of colurs whereas, in the 16th century the use of colour is been transformed into subdue grey tone and in coming of the 19th century use of dark colours is been encouraged and in 20th century its again went into the use of flat tones of grey and the choice of colours has become flat and in single tone. One can see it in image below the modification happened in the colours. This analysis will help the designers to plan the use of colour in upcoming Naamghars and also use of red, blue and golden is been extensively used in Naamghars because of its association with Vishnu like use of red colour is coming from Nirmali flower, which is associated with Shankardeva. Use of blue colour in Naamghar has been done because it has been associated with Vishnu and Krishna. Shades of golden have been used because of the brass metal (here Xorai) object associated with Vaishnavite tradition of Assam.
(a) Colour palette of Barpeta Satra Main gate
(b) Timeline of Main gate in different Naamghars of Assam
Fig. 4.69: Century wise colour palette of Main gate of various Naamghar and Satra (a) Colour palette of Barpeta Satra Main gate; (b) Timeline of Main gate in different Naamghars of Assam
(Illustration: Researcher)
ii. Study of Colour palette variation in Outer structure of Naamghar
Similarly the colour palette of Outer structure of Naamghar (Fig. 4.70) has been created from 1450 till 2000 years. One can see the variations in terms of colours from the tone of sepia greens between 14th and 15th century and then totally moving towards dark colours between 16th to 17th century and between 18th to 19th century the colour palette moved towards dark shades of green colours. Further in19th century onwards the tone of colour palette moved towards dark grey and brown colours.
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Fig. 4.70: Century wise colour palettes of outer side of Naamghar and Satra
iii. Study of Colour palette variation in Main door of Naamghar
Fig. 4.71: Century wise colour palette of main gate of Naamghar and Satra (Illustration: Researcher)
iv. Study of Colour palette variation in Manikut of Naamghar