Image pickup apparatus equipped with display section and method of controlling the same

An image pickup apparatus that is capable of reducing degradation of image quality of the whole display screen of a display section while improving display delay with respect to an observed area. In an image pickup apparatus, an image pickup section picks up an image of an object, and a development processor generates image data by developing input data acquired by the image pickup section. A first image generation unit generates a first image by performing image processing on part of the image data. A second image generation unit performs predetermined image processing on the image data to thereby generate a second image which is different in the number of steps of image processing from the above image processing. An image synthesis section generates a third image by synthesizing the first image with the second image, and a display device displays the third image.