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, 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, wherein the instructions further cause the image-processing device to perform: selecting a first internal reference pixel corresponding to the first internal pixel and a first external reference pixel corresponding to the first external pixel; assigning a first weight to the color value of the first internal pixel, the first weight being larger in a case that a first distance between the first target pixel and the first internal reference pixel is smaller; and assigning a second weight to the color value of the first external pixel, the second weight being larger in a case that a second distance between the first target pixel and the first external reference pixel is smaller, and wherein the color value of the first target pixel is changed using the first weight and the second weight.