Image capturing system and method thereof

The invention provides an image capturing system comprises a storage device and a transcoder module coupled to the storage device. The storage device stores image data of a captured still image compressed by a first coding format configured. The transcoder module transcodes the image data compressed by the first coding format into output image data compressed by a second coding format and outputting the output image data to an external device when the external device requests the captured still image. The invention provided image capturing system uses a first coding format to compress the image data to improve compression performance and reduce size of compressed image, which enables the storage device to store more images and improves its utilization ratio.