An image forming apparatus comprising an optical writing apparatus, comprising: first writing means for writing image data (DATA1) in a first memory in synchronization with a first clock signal (CLKV); first reading means for reading out the image data (DATA2) from the first memory in synchronization with a second clock signal (CLKE); first processing means for applying image processing and pattern composition to the image data (DATA2) in synchronization with the second clock signal (CLKE); second writing means for writing the image data (DATA3) in a second memory in synchronization with the second clock signal (CLKE); second reading means for reading out the image data (DATA4) from the second memory in synchronization with a third clock signal (CLKW); second processing means for processing the image data (DATA4) in synchronization with the third clock signal (CLKW); means for outputting a light control signal based on the processed image data (DATA5) in synchronization with the third clock signal (CLKW); and converters configured to generate write enable signals allowing the writing of the image data (DATA1, DATA3) in the first and second memories (12, 14) respectively, and configured to generate read enable signals allowing the reading-out of the image data (DATA2, DATA4) from the first and second memories (12, 14) respectively, when the last address of the respective memories (12, 14) is reached, when the first and second writing means write the image data (DATA1, DATA3) in the respective memories (12, 14); wherein the second clock signal (CLKE) has a frequency higher than a frequency of the first clock signal (CLKV) but lower than a frequency of the third clock signal (CLKW). first writing means for writing image data (DATA1) in a first memory in synchronization with a first clock signal (CLKV); first reading means for reading out the image data (DATA2) from the first memory in synchronization with a second clock signal (CLKE); first processing means for applying image processing and pattern composition to the image data (DATA2) in synchronization with the second clock signal (CLKE); second writing means for writing the image data (DATA3) in a second memory in synchronization with the second clock signal (CLKE); second reading means for reading out the image data (DATA4) from the second memory in synchronization with a third clock signal (CLKW); second processing means for processing the image data (DATA4) in synchronization with the third clock signal (CLKW); means for outputting a light control signal based on the processed image data (DATA5) in synchronization with the third clock signal (CLKW); and converters configured to generate write enable signals allowing the writing of the image data (DATA1, DATA3) in the first and second memories (12, 14) respectively, and configured to generate read enable signals allowing the reading-out of the image data (DATA2, DATA4) from the first and second memories (12, 14) respectively, when the last address of the respective memories (12, 14) is reached, when the first and second writing means write the image data (DATA1, DATA3) in the respective memories (12, 14); wherein the second clock signal (CLKE) has a frequency higher than a frequency of the first clock signal (CLKV) but lower than a frequency of the third clock signal (CLKW).