Image monitoring device and method capable of adaptively placing a plurality of images

An image monitoring device comprising:

• a network interface configured to receive a plurality of images from a plurality of cameras through at least one channel;
• a user interface configured to allow a user to select at least a first image to be displayed on a screen from among the plurality of images that are received;
• an image decoder configured to decode the first image that is selected;
• and
• an image synthesizer configured to display the first image, that is decoded, on the screen,
• wherein the screen comprises a plurality of unit cells,
• wherein the image synthesizer is further configured to, based on a second image being additionally selected via the user interface:
• display the first image and the second image together on the screen;
• and
• increase an amount of the plurality of unit cells by expanding the plurality of unit cells first in a horizontal row direction and then in a vertical column direction, based on a condition that a number of the plurality of unit cells in the horizontal row direction is greater than or equal to a number of the plurality of unit cells in the vertical column direction is always satisfied.