If a fallback processing involving lossy compression occurs in PDL data including a special pattern, such as a texture pattern, an electronic watermark, or an Anoto pattern, the performance of the special pattern cannot be sufficiently exhibited by image degradation due to the compression. Moreover, in order to obtain an image quality capable of sufficiently exhibiting the performance of the special pattern, a high-capacity memory is necessary to raise the cost. Document information and additional information are sequentially received from other device, and a pre-preparation processing for bit-mapping the document information is started, and upon receipt of the additional information by a receiving unit, a bit map is generated using the information (display list) obtained by the pre-preparation processing for the document information. The generated bit map is compressed and the compressed bit map is associated with the information that is obtained by the pre-preparation processing for the additional information.