Image processing apparatus that acquires image data from removable driver and image processing method

In an image processing apparatus, a data handling unit (a) estimates a size of the intermediate data on the basis of the image data, and (b) selects one of a first rendering mode and a second rendering mode on the basis of a size of the image data and the estimated size of the intermediate data. In the first rendering mode, the data handling unit makes a copy of the image data and stores the copy in the storage device and causes a rendering unit to generate bitmap image data from the image data stored in the storage device. In the second rendering mode, the data handling unit causes the rendering unit to generate the bitmap image data from the image data stored in the removable drive.