1. An image processing apparatus comprising: an obtaining unit configured to obtain image data from a detachable memory unit; a control unit configured to execute predetermined screen processing on the obtained image data; and a presuming unit configured to estimate whether the image data obtained by the obtaining unit is image data read by a scanner, wherein in a case where the presuming unit estimates that the image data obtained by the obtaining unit is image data read by the scanner, the control unit performs control not to execute the predetermined screen processing on the obtained image data.