Abstract: A determining unit determines whether a background pixel value of image data matches a predetermined comparison value. A replacing unit replaces, when the determining unit determines that the background pixel value does not match the comparison value, a pixel value of a pixel of the image data with a replacing value that is obtained by subtracting the pixel value from a predetermined maximum pixel value. An encoding unit generates encoded data by encoding the image data in which the pixel value is replaced with the replacing value by using a predetermined encoding system.

Abstract: An attribute determining unit determines an attribute of image data of an image. A still-image extracting unit extracts, when the attribute is a moving image, a still image from the image data. A feature-amount obtaining unit obtains a feature amount from image data of the still image and image data of a still image when the attribute is the still image. An arrangement-position determining unit determines an arrangement position of a display area based on the feature amount. A display-image generating unit generates a thumbnail image from the still image and displays a list of thumbnail images in the display area, based on the arrangement position and the display area.