1. A video image conversion method for processing an interlaced field, wherein the interlaced field has a plurality of scanning lines, each of the scanning lines comprises a plurality of pixels represented as P(x,n), and the plurality of corresponding pixels is represented as Q(x,n), where x represents the x th scanning line, n represents the n th pixel on each of the scanning lines, and the video image conversion method comprises: defining a target pixel, and the target pixel being located between the pixels P(x,n) and P(x+1,n) on two neighboring scanning lines; obtaining a reference value R(x,n), wherein the reference value R(x,n) is an arithmetic mean of Q(x,n) and Q(x+1,n), where Q(x,n) and Q(x+1,n) are the pixel values of the pixel P(x,n) and the pixel P(x+1,n), respectively; composing the pixel P(x,n−i) and the pixel P(x+1,n+i) of two neighboring scanning lines as a pair by using the target pixel as a center, and calculating a comparison value of each pair (abs[Q(x,n−i)−R(x,n)]+abs[Q(x+1,n+i)−R(x,n)]), where abs[i]=0, 1, 2,. .. , and abs[ ] represents obtaining an absolute value; comparing each of the comparison values, and obtaining a pair of pixels P(x,n−j) and P(x+1,n+j) having a minimum value, where abs[j]=0, 1, 2,. .. ; and calculating an arithmetic mean of Q(x,n−j) and Q(x+1,n+j).