Patent ID: 7372591

Claim:
An image forming device comprising: image data generation means for generating image data from original data; compression determining means for determining whether or not the image data generated by the image data generating means is to be compressed; compression means for compressing at least a part of the image data required to be compressed as determined by the compression determining means among the image data generated by the image data generation means; memory means for storing a remaining part of the image data remained non-compressed as determined by the compression determining means and the part of the image data compressed by the compression means; decompressing means for decompressing the part of the image data compressed by the compression means and stored in the memory means; a printing engine for forming an image on an image recording medium based on the image data; and transfer means for transferring the non-compressed image data stored in the memory means and the decompressed image data decompressed by the decompressing means to the printing engine, wherein the compression determining means determines necessity of data compression on a basis of the image data and a data transferring performance from the memory means to the transfer means, wherein the compression determining means employs a reference value indicative of the data transferring performance from the memory means to the transfer means, the reference value being based on the following formula: Lr=Bl /( Bg*De ), where Lr is the reference value, Bl is data volume that can be read from the memory means within a predetermined time period, Bg is gradation value of the image data, and De is resolution.