Abstract: The rendering device defines, based on the width of the line to be rendered on a screen comprising multiple pixels and defined by two points on the screen, an interpolation range for a line segment having its ends at the two points. The rendering device further determines whether a pixel is contained in the interpolation range. Then, the rendering device renders a line formed by the pixels on the line segment and the pixels determined to be contained in the interpolation range. Then, the rendering device can specify the pixels for rendering the line based only on information regarding the line width. Consequently, the amount of information to handle in rendering is reduced and the rendering can be expedited. Furthermore, the amount of information prepared in advance for rendering is reduced and thus the rendering device can be downsized.