Method and device for acquiring digital image data

The invention discloses a method and a device for acquiring digital image data. The method comprises the steps as follows: opening an ultraviolet light source after an Mth horizontal synchronizing signal is sent to an image sensor, wherein the ultraviolet light source is used for illuminating a bill to be scanned to enable the image sensor to collect an ultraviolet image of the bill to be scanned, and M is a positive integer; starting first timing when an (M+N)th horizontal synchronizing signal is sent to the image sensor, and closing the ultraviolet light source when timing of a first preset time length is completed through the first timing, wherein N is a positive integer, and the first preset time length is greater than the pulse width of the (M+N)th horizontal synchronizing signal and smaller than the working cycle of the (M+N)th horizontal synchronizing signal; and acquiring ultraviolet digital image data corresponding to the working cycle of the (M+N)th horizontal synchronizing signal. According to the technical scheme of the invention, fluorescent fibers contained in the bill can be clearly displayed in a digital image, and the brightness of the background part of the digital image except the fluorescent fibers is not affected.