A method of controlling an operation of a display device (200, 600, 700), the method comprising: receiving a power-off signal; storing a system booting file and a predetermined snapshot image in a self-refresh memory block based on a predetermined self-refresh mode, wherein the predetermined snapshot image corresponds to at least one of an image of a content data, a default image and a specific content image; and wherein the predetermined self-refresh mode includes a first predetermined self-refresh mode, a second predetermined self-refresh mode; and a third predetermined self-refresh mode; receiving a power-on signal; booting a system by extracting the system booting file from the self-refresh memory block; and controlling, by a controller (640, 710), a display module in the display device (200, 600, 700) to display one of the predetermined snapshot images based on one of the predetermined self-refresh modes, wherein the content data is contiguously displayed by the display module when the power-off signal is received based on the first predetermined self-refresh mode, wherein the default image is displayed by the display module after the power-on signal is received based on the second predetermined self-refresh mode, wherein the specific content image is displayed by the display module after the power-on signal is received, wherein the specific content is automatically selected according to a user access frequency based on the third predetermined self-refresh mode, wherein the selected content corresponds to content most frequently executed within a predetermined time; and wherein the self-refresh memory block corresponds to a memory block configured to be activated when the display device (200, 600, 700) is deactivated. receiving a power-off signal; storing a system booting file and a predetermined snapshot image in a self-refresh memory block based on a predetermined self-refresh mode, wherein the predetermined snapshot image corresponds to at least one of an image of a content data, a default image and a specific content image; and wherein the predetermined self-refresh mode includes a first predetermined self-refresh mode, a second predetermined self-refresh mode; and a third predetermined self-refresh mode; receiving a power-on signal; booting a system by extracting the system booting file from the self-refresh memory block; and controlling, by a controller (640, 710), a display module in the display device (200, 600, 700) to display one of the predetermined snapshot images based on one of the predetermined self-refresh modes, wherein the content data is contiguously displayed by the display module when the power-off signal is received based on the first predetermined self-refresh mode, wherein the default image is displayed by the display module after the power-on signal is received based on the second predetermined self-refresh mode, wherein the specific content image is displayed by the display module after the power-on signal is received, wherein the specific content is automatically selected according to a user access frequency based on the third predetermined self-refresh mode, wherein the selected content corresponds to content most frequently executed within a predetermined time; and wherein the self-refresh memory block corresponds to a memory block configured to be activated when the display device (200, 600, 700) is deactivated.