A method and an electronic device with image data generating are disclosed. The electronic device includes: one or more processors; and memory storing instructions configured to cause the one or more processors to: input an input image to a target model that performs segmenting on the input image to generate a segmented image whose pixels have respective class labels predicted by the target model, calculate an optimization value for the input image based on the segmented image and based on a class label of a first grid area among a plurality of grid areas of a guide image, and optimize the input image based on the optimization value.