IMAGE-RENDERING DEVICE, IMAGE-RENDERING METHOD, AND NAVIGATION DEVICE

摘要

This image-rendering device partitions a large region, elements being the smallest constituent units thereof, into a plurality of small regions each comprising a plurality of elements. The image-rendering device then computes low-resolution distance data that indicates the shortest distance from a base line, on which the change in color in a gradient is based, to the plurality of small regions. Then, for each small region, the image-rendering device associates the following with each other and stores same in a high-resolution-data storage unit: low-resolution distance data that holds the minimum distance from the base line; and high-resolution distance data that holds the minimum distance from the base line to each element. The image-rendering device then obtains, from the high-resolution-data storage unit, the high-resolution distance data associated with low-resolution distance data that is stored in the high-resolution-data storage unit and matches the computed low-resolution distance data. The image-rendering device renders the gradient on the basis of said high-resolution distance data, making it possible to reduce the number of times that the shortest distances between the base line and pixels are calculated.