1. An image-processing device comprising: a processor; and a memory storing computer-readable instructions therein, the computer-readable instructions, when executed by the processor, causing the image-processing device to perform: identifying a first region and a second region in a target image represented by target image data, the first region representing an encircling line for identifying a specific sub-region in the target image, the first region including a plurality of pixels, the second region being different from the first region, the second region including: an inside region that is surrounded by the first region; and an outside region that is outside the first region, the inside region having a plurality of internal pixels, the outside region having a plurality of external pixels; and changing a color value of each of the plurality of pixels using a color value of one of the plurality of internal pixels and a color value of one of the plurality of external pixels; wherein the changing changes a color value of a first target pixel included in the plurality of pixels using a color value of a first internal pixel included in the plurality of internal pixels and a color value of a first external pixel included in the plurality of external pixels; and wherein the changing changes a color value of a second target pixel included in the plurality of pixels using a color value of a second internal pixel included in the plurality of internal pixels and a color value of a second external pixel included in the plurality of external pixels.