In photography, bokeh ( BOH-k or BOH-kay, Japanese: [boke]) is the aesthetic quality of the blur produced in out-of-focus parts of an image. Bokeh has also been defined as 'the way the lens renders out-of-focus points of light'. Differences in lens aberrations and aperture shape cause very different bokeh effects. Some lens designs blur the image in a way that is pleasing to the eye, while others produce distracting or unpleasant blurring ('good' and 'bad' bokeh, respectively). Photographers may deliberately use a shallow focus technique to create images with prominent out-of-focus regions, accentuating their lens's bokeh. Bokeh is often most visible around small background highlights, such as specular reflections and light sources, which is why it is often associated with such areas. However, bokeh is not limited to highlights, blur occurs in all regions of an image which are outside the depth of field. Origin The term comes from the Japanese word boke (/), which means 'blur' or 'haze', resulting in boke-aji (), the 'blur quality'. This is derived as a noun form of the verb bokeru, which is written in several ways, with additional meanings and nuances: refers to being blurry, hazy or out-of-focus, whereas the and spellings refer to being mentally hazy, befuddled, childish, senile, or playing stupid. Jisaboke () (literally, 'time difference fog') is the term for jet lag.