1. An image processing device comprising: a receiver configured to receive a drawing command to execute a drawing process, the drawing command including object data; a processor; and memory storing instructions that, when executed by the processor, cause the image processing device to: determine whether the receiver has received the drawing command; specify whether the received drawing command is an image drawing command in response to a determination that the receiver has received the drawing command; determine, in response to a specification that the received drawing command is the image drawing command, that a gray color of gray pixels included in the object data is to be reproduced by a mixture of multiple color materials; generate, in response to a determination that the gray color is to be reproduced by the mixture of multiple color materials, first gray reproduction information representing that the gray color for each gray pixel is to be reproduced by the mixture of the multiple color materials; determine, in response to a specification that the received drawing command is not the image drawing command, that the gray color of gray pixels included in the object data is to be reproduced by black coloring material; generate, in response to a determination that the gray color is to be reproduced by the black coloring material, second gray reproduction information representing that the gray color for each gray pixels is to be reproduced by the black coloring material; generate raster data expressed in a first color space by rendering the object data to include the first gray reproduction information or the second gray reproduction information for each gray pixel; convert the raster data from the first color space to a second color space based on a corresponding one of the first and second gray reproduction information included in the raster data, the second color space being different from the first color space, and wherein, in the second color space, the gray color of the gray pixels is reproduced by a corresponding one of the black coloring material and the mixture of multiple color materials; alter, in response to the specification that the received drawing command is the image drawing command, original color components of the gray color of the gray pixels included in the object data to predetermined color components that are different from the original color components of the gray color in the first color space, and thereby generate the first gray reproduction information based on the predetermined color components of the gray pixels; determine, in the first color space, whether a gray pixel of the data includes color components that match the predetermined color components; determine, in the response to a determination that the gray pixel includes the color components that match the predetermined color components that the gray color is to be reproduced by the mixture of multiple coloring materials; return, in response to a determination that the gray pixel included the color components that match the predetermined color components and that the gray color is to be reproduce by the mixture of multiple coloring materials; the predetermined color components of the gray pixel to the original color components of the gray color in the first color space; after returning the predetermined color components of the gray pixel to the original color components of the gray pixel in the first color space, convert the raster data including the gray pixel including the returned original color components form the first color space to the second color space so that the gray color is produce by the mixture of multiple coloring materials; determine, in the first color space, whether the gray pixel of the raster data includes color components that match the original color components of the gray color; and convert, in response to a determination that the gray color, the raster data including the gray pixel form the first color space to the second color space so that the gray color is produced by the black coloring material.