Image acquisition method and image acquisition system

An image acquisition system, which is configured to acquire, with respect to a sample including a cell in a fluid that is contained in a vessel, a phase contrast image picked up by a phase contrast method with use of an image pickup apparatus, the image acquisition system comprising:

• an exposure acquisition image acquiring unit configured to acquire, when a target range of the sample for which the phase contrast image is to be acquired is divided into N areas, N being an integer equal to or more than 3, exposure acquisition images by picking up images of M areas out of the N areas by the phase contrast method, M being an integer equal to or more than 2, with M satisfying M<N;
• an exposure calculation unit configured to calculate appropriate exposure conditions with respect to the exposure acquisition images;
• an exposure condition determination unit configured to determine exposure conditions for picking up images of the respective N areas, based on positions of the M areas in the target range and on the appropriate exposure conditions with respect to the exposure acquisition images;
• an image pickup order determination unit configured to determine an image pickup order of the N areas based on the exposure conditions for the respective N areas;
• an images-to-be-combined acquisition unit configured to acquire images-to-be-combined by picking up the images of the respective N areas by the phase contrast method, based on the image pickup order and on the exposure conditions for the respective N areas;
• and
• an image combining unit configured to combine the images-to-be-combined.