Fig. 1. Examples of BMP images. (a) Original image; (b) cropped image

Fig. 2. Binary image

Fig. 3. Preprocessing steps

Fig. 4. Schematic diagram of target projection superposition

Fig. 5. Schematic diagram of back projection

Fig. 6. Examples of tomographic images. (a)‒(d) Images generated by improved FBP algorithm; (e)‒(h) images generated by traditional FBP algorithm

Fig. 7. Three-dimensional side images of finger bones reconstructed by different algorithms. (a)(b) Improved FBP algorithm; (c)(d) traditional FBP algorithm