Determination of Tangerine Volume Using Image Processing Methods

Figures & data

Table 1 Weight and volumes of tangerines used in this study

		Volume* (cm^3)					Volume* (cm^3)
Sample No.	Mass (g)	WDM	EAM	SM	Sample No.	Mass (g)	WDM	EAM	SM
1	75.6	86.4	83.1	87.4	26	74.7	86.7	79.2	90.4
2	60.9	67.0	59.1	63.2	27	65.9	72.6	69.3	71.8
3	84	100.2	93.6	103.8	28	59.9	71.3	64.1	72.0
4	72.6	80.2	72.9	79.3	29	73.0	82.7	73.4	85.9
5	64.5	73.8	70.7	76.0	30	88.3	99.7	92.0	99.7
6	62.6	69.1	63.8	69.2	31	76.8	85.2	72.6	81.9
7	60.6	64.6	58.7	65.8	32	94.3	98.7	95.3	96.7
8	64.8	72.1	64.7	72.9	33	75.2	82.4	74.8	82.0
9	72.9	82.3	72.7	85.3	34	67.8	74.2	67.5	74.5
10	86.3	96.8	90.1	101.2	35	60.5	67.9	60.5	68.9
11	72.5	80.1	77.2	83.0	36	74.6	81.9	71.7	79.6
12	72.5	79.7	71.2	85.2	37	87.0	100.7	90.9	101.0
13	64.1	69.8	61.0	70.3	38	69.9	77.8	77.5	76.3
14	90.9	107.6	99.9	110.4	39	59.8	63.4	54.8	59.0
15	93.9	109.8	98.7	117.2	40	80.6	88.1	82.1	83.2
16	69.9	75.5	73.1	75.2	41	77.0	95.6	88.6	93.2
17	79.7	95.2	87.4	100.0	42	99.4	113.2	105.0	113.0
18	69.2	73.6	67.4	73.0	43	69.3	79.0	70.5	72.1
19	79.6	92.5	74.9	96.6	44	81.6	89.3	80.7	87.9
20	84.7	92.9	82.8	94.2	45	75.3	81.0	74.3	82.7
21	85.7	95.7	87.9	96.0	46	67.1	73.2	66.5	76.3
22	71.6	77.3	74.3	76.9	47	67.6	76.9	68.6	80.1
23	61.8	64.6	55.3	63.3	48	83.4	95.4	87.1	98.5
24	62.3	68.9	60.2	68.7	49	78.6	87.4	84.0	91.2
25	67.9	76.2	68.5	76.9	50	64.8	70.0	61.4	69.9
*WDM: water displacement method; EAM: ellipsoid approximation method; and SM: segmentation method.

Figure 1 Schematic of developed machine vision system.

Figure 2 (a) front view: acquire two perpendicular images of tangerine and calculation of b and c diameters; top view: acquire one image with camera 1 and calculation of a diameter.

Figure 3 The dimensions of an ellipsoid.

Figure 4 (a) Tangerine fruit; (b) segmentation of tangerine; (c) extraction of two diameters of one surface of one sector; (d) thickness of sector and its surface areas.

Figure 5 (a) Tangerine volume measured using water displacement method (WDM) and ellipsoid approximation method (EAM) with the line of equality; (b) bland–Altman plot for the comparison of tangerine volumes measured with water displacement and ellipsoid approximation methods; outer lines indicate the 95% limits of agreement (–1.66 ;–12.91 cm ³) and center line shows the average difference (−7.3 cm ³).

Table 2 t-test analyses on comparing volume measurement methods

Paired t-test*		95% confidence interval for the mean difference
WDM & EAM	WDM & SM	WDM & EAM	WDM & SM
Different (P < 0.0001)	Same (P = 0.1032)	−8.1; −6.47	−0.14; 1.45
*WDM: water displacement method; EAM: ellipsoid approximation method; and SM: segmentation method.

Figure 6 (a) Tangerine volume measured using water displacement method (WDM) and segmentation method (SM) with the line of equality; (b) bland–Altman plot for the comparison of tangerine volumes measured with water displacement and segmentation methods; outer lines indicate the 95% limits of agreement (−4.83; 6.14 cm ³) and center line shows the average difference (0.66 cm ³).