A transmission device comprising: an image processing unit configured to process ultra-high-definition image data with high frame rate to obtain image data in a base format for obtaining a high-definition image with base frame rate, image data in a first extension format for obtaining an ultra-high-definition image with base frame rate, and image data in a second extension format for obtaining an ultra-high-definition image with high frame rate; an image encoding unit configured to generate a base video stream including encoded image data of the image data in the base format, and two extended video streams including encoded image data of the image data in the first extension format and encoded image data of the image data in the second extension format, respectively, or one extended video stream including both the encoded image data of the image data in the first extension format and the encoded image data of the image data in the second extension format; and a transmission unit configured to transmit a container in a predetermined format including the base stream and the two or one extended video stream, wherein the image processing unit performs a first-ratio mixing processing on the ultra-high-definition image data with high frame rate in units of two temporally-consecutive pictures to obtain first ultra-high-definition image data with base frame rate, performs a second-ratio mixing processing on the ultra-high-definition image data with high frame rate in units of the two temporally-consecutive pictures to obtain the image data in the second extension format, performs a downscale processing on the first ultra-high-definition image data with base frame rate to obtain the image data in the base format, and takes a difference between second ultra-high-definition image data with base frame rate obtained by performing an upscale processing on the image data in the base format and the first ultra-high-definition image data with base frame rate to obtain the image data in the first extension format. an image processing unit configured to process ultra-high-definition image data with high frame rate to obtain image data in a base format for obtaining a high-definition image with base frame rate, image data in a first extension format for obtaining an ultra-high-definition image with base frame rate, and image data in a second extension format for obtaining an ultra-high-definition image with high frame rate; an image encoding unit configured to generate a base video stream including encoded image data of the image data in the base format, and two extended video streams including encoded image data of the image data in the first extension format and encoded image data of the image data in the second extension format, respectively, or one extended video stream including both the encoded image data of the image data in the first extension format and the encoded image data of the image data in the second extension format; and a transmission unit configured to transmit a container in a predetermined format including the base stream and the two or one extended video stream, wherein the image processing unit performs a first-ratio mixing processing on the ultra-high-definition image data with high frame rate in units of two temporally-consecutive pictures to obtain first ultra-high-definition image data with base frame rate, performs a second-ratio mixing processing on the ultra-high-definition image data with high frame rate in units of the two temporally-consecutive pictures to obtain the image data in the second extension format, performs a downscale processing on the first ultra-high-definition image data with base frame rate to obtain the image data in the base format, and takes a difference between second ultra-high-definition image data with base frame rate obtained by performing an upscale processing on the image data in the base format and the first ultra-high-definition image data with base frame rate to obtain the image data in the first extension format.