1. An image processing apparatus comprising: an obtaining unit adapted to obtain an image; an extraction unit adapted to extract pixel count information indicating a pixel count of the obtained image from the obtained image; a determination unit adapted to determine whether or not the obtained image contains resolution information indicating a resolution of a printed image related to the obtained image; a resolution determination unit adapted to determine a resolution of a printed image related to the obtained image on the bases of the pixel count information extracted by said extraction unit in a case where said determination unit determines that the obtained image does not contain the resolution information; a sheet-size determination unit adapted to determine a sheet-size of a sheet, to be used for printing the obtained image, based on the pixel count information extracted by said extraction unit; a transformation unit adapted to transform the obtained image to a transformed-image, having a size suitable for the determined sheet-size, based on the pixel count information extracted by said extraction unit and a printing unit adapted to print the transformed-image on the sheet, the size of which is determined by said sheet-size determination unit, with the resolution determined by said resolution determination unit in a case where said determination unit determines that the obtained image does not contain the resolution information.