This paper proposes a real-time image selection algorithm for fingerprint recognition system, which uses the embedded camera of the mobile device. In general, auto-focusing algorithms of the camera system use the gradient measures to estimate high-frequency components of an image. In mobile device, images are greatly affected by environmental light sources. Therefore, obtained image might not qualify for the fingerprint recognition system, even when the image is focused. Consequently, image should be investigated whether it is usable or not. Variance-Modified-Laplacian of Gaussian(VMLOG) and Image quality index(QI) proposed in this paper solve such problem. VMLOG considers high-frequency component and repeatable patterns of ridges, Experimental results shows that the processing time of the proposed algorithm is enough fast to be adapted in real time system as like mobile device and the proposed algorithm selects exactly a recognizable image.