正上下 meaning in English

overunderr
over、under

In figure 11 , the pixel being affected gets its original value multiplied by 5 , while the pixels immediately above , below , to the left , and to the right are multiplied by ? 1 , with the resulting values added together and multiplied by the affected pixel to produce a new value for that pixel
图11 ，象素先把原来的该象素的值乘以5 ，它正上下左右都乘以- 1 ，把周围的这些加在一起和乘以5的那个中心象素一起计算出新的值。