Patent ID: 8840221

Claim:
An image forming apparatus which reads a test pattern formed by ejecting liquid droplets onto a recording medium to adjust an ejection timing of the liquid droplets, comprising: a reading unit including a light emitting unit which irradiates a light onto the recording medium, and a light receiving unit which receives a reflected light from the recording medium, a relative movement unit which relatively moves the recording medium or the reading unit at a constant speed, a second detected data obtaining unit which obtains one or more second detected data sets of the reflected light which is received from a scanning position of the light by the light receiving unit while the reading unit moves relatively with respect to the recording medium before the test pattern is formed; a first detected data obtaining unit which obtains one or more first detected data sets of the reflected light which is received by the light receiving unit when the light moves over the test pattern at generally the same scanning position as the scanning position while the reading unit moves relatively with respect to the recording medium after the test pattern is formed; and a signal correction unit which calculates a proportion of the first detected data sets relative to the second detected data sets to align a local maximum value of the first detected data sets such that the local maximum value is generally constant.