Table 2.

Description of 44 computed image features in the initial feature pool

Image	Feature Number	Feature Description
Original FFDM image	1 – 3	Average and absolute difference of density values, and multiplication of above 2 features.
FGT map	4 – 7	Average and absolute difference of mean high density value, difference ratio and multiplication of the first 2 features.
	8 – 10	Average and absolute difference of FGT volume, and multiplication of above two features.
	11 – 13	Average and absolute difference of standard deviation of pixel values, and multiplication.
	14 – 17	Average and absolute difference of skewness and kurtosis of pixel values.
Focal density map	18 – 21	Average and absolute difference of focal density value, difference ratio and multiplication of the first 2 features.
	22 – 29	Average and absolute difference of mean, standard deviation, skewness, and kurtosis of detected and segmented focal density regions.
Local fluctuation map	29 – 33	Average of mean, standard deviation, skewness and kurtosis of pixel values.
	34 – 37	Absolute difference of mean, standard deviation, skewness and kurtosis of pixel values.
	38 – 41	Multiplication of average and absolute difference of mean, standard deviation, skewness and kurtosis of pixel values
DOG map	42 – 44	Average and absolute difference of mean pixel values, multiplication of above 2 features.