Image control method and image display device

1. An image display method, comprising:

obtaining a composite image that was displayed immediately prior to when a video signal is lost, the composite image comprising an image in which a first image of an on-screen display (OSD) menu is combined with a display image that is based on the video signal before being lost;

after the video signal is lost, combining a second image of the OSD menu with the composite image to obtain a combined composite image; and

displaying the combined composite image.

2. The image display method according to claim 1 , further comprising:

storing composite images of frames that were displayed,

wherein the combining comprises combining a new image of the OSD menu with the composite image of a latest frame among the stored composite images of the frames.

3. The image display method according to claim 2 , wherein the combining the new image is repeated until a setting process using the OSD menu is ended, in a state in which the video signal is lost.

4. The image display method according to claim 1 , further comprising:

determining that the video signal is lost when a resolution of the display image based on the video signal cannot be detected from a synchronization signal of the video signal.

5. The image display method according to claim 1 , further comprising:

before the image signal is not lost, storing data of a composite image of a first frame to be displayed in a first storage unit and storing, in a second storage unit, data of a display image of a second frame stored in the first storage unit, the second frame being a frame whose display image is displayed before the display image of the first frame is displayed; and

after the video signal is lost, storing blank data in which all pixels are black to the first storage unit.

6. The image display method according to claim 5 , wherein, when the blank data is stored in the first storage unit, the second image of the OSD menu is combined with the display image of the second frame stored in the second storage unit.

7. An image display device, comprising:

a processor coupled to a memory storing instructions, the processor being configured to:

combine a first image of an on-screen display (OSD) menu with a display image that is based on a video signal before lost to obtain a composite image; and

after the video signal is lost, combine a second image of the OSD menu with the composite image to obtain a combined composite image; and

an image output unit that displays the combined composite image.