3D fringe projection measurement techniques are increasingly important in production for automation, quality control,
reversal engineering, and biomedical engineering because of the advantages of non-contact operation, full-field
acquisition and automatic data processing. With the advent of DLP (Digital Light Processing) projectors, digital fringe
pattern projection techniques have been widely studied in academia and applied to industries. The experimental data
from living profile of fringe patterns show that the obtained intensity has some fluctuation, which cause the calculated
phase data inaccuracy. This paper presents one software method to eliminate the fluctuation between fringe patterns.
Four-step phase-shifting algorithm is used to calculate the wrapped phase data, so four fringe pattern images having pi/2
shift in between need to be captured. Because of the fluctuation of intensity, the captured fringe patterns have an up or
down shift among the four images. By considering the histogram of each fringe pattern, we present one compensation
method to eliminate the fluctuation between fringe patterns. Simulated data are first tested by generating fringe patterns
with fluctuation. Then experimental data from a 3D imaging system demonstrate the validity for calculating the phase
and shape information with high accuracy. The results show that the proposed method eliminates the fluctuation between
fringe pattern images to give accurate shape data information.