Patent ID: 8054478

Claim:
An image forming apparatus, comprising: a language analysis unit for analyzing print data and generating data having an intermediate format between the print data and bitmap data generated based on the print data; an image processing unit for rasterizing the generated data having the intermediate format for each band by using the predetermined number of lines and generating the bitmap data; a memory for holding the data for which rasterizing processing is being performed by the image processing unit; a printing unit for performing printing based on the generated bitmap data; and a number-of-line switching unit for switching the number of lines of the band in the rasterizing processing of the image processing unit according to whether the print data is data that can include transparency processing data or not, wherein in the print data, a series of transparency processing which is performed in the rasterizing processing of the image processing unit can be specified, the series of transparency processing including first transparency processing in which source data to be newly added to destination data, which is background, is allowed to be transparent according to alpha channel data which can indicate opacity for each pixel to obtain a first transparency processing result data, and including second transparency processing in which the first transparency processing result data is used as the destination data or the source data to obtain a second transparency processing result data; the transparency processing data indicates the destination data, the source data, and the alpha channel data; when the print data is the data that can include the transparency processing data, the number-of-line switching unit switches the number of lines to the smaller number of lines as compared with a case where the print data is not the data that can include the transparency processing data; and the image processing unit allows the memory to hold the data for which the rasterizing processing is being performed by using an area having a size according to the number of lines switched by the number-of-line switching unit, the area being ensured in the memory as a work area for the rasterizing processing.