Head mounted display device displaying thumbnail image and method of controlling therefor

A head mounted display (HMD) device, comprising:

• a sensor to detect a front direction of the HMD device;
• a display to display a part of a surround video image based on a front direction of the HMD device,
• wherein the display displays a first region among the surround video image when the front direction of the HMD device corresponds to a first direction,
• wherein the surround video image is an image provided around the HMD device,
• wherein the surround video image comprises the first region and a second region which is not displayed when the first region is displayed, and
• a processor to:
• control the display to display a thumbnail image which is related to the surround video image based on an image type of the surround video image corresponding to at least one of a cylinder image type, a sphere image type or a hemisphere image type, and the thumbnail image is a downsized image of the surround video image with a reference ratio,
• control the display to display a progress bar indicating a progress status of the surround video image,
• wherein the thumbnail image comprises a first image corresponding to the first region of the surround video image and a second image corresponding to the second region of the surround video image, and
• display the first image corresponding to the first region at a center of the thumbnail image when the thumbnail image is displayed after the first region of the surround video image is displayed.