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: acquiring target image data including each pixel value of a plurality of pixels, the target image data representing a target image by using the plurality of pixels; extracting a plurality of photographic pixels and a plurality of non-photographic pixels from the plurality of the pixels in the target image; determining a text color value by using a plurality of text pixels included in the plurality of non-photographic pixels, the plurality of text pixels constituting a text image; determining a background color value by using a plurality of background pixels included in the plurality of non-photographic pixels, the plurality of background pixels constituting a background image; storing the background color value in the memory; generating non-photographic correspondence data by using the text color value and the stored background color value; converting, by using the non-photographic correspondence data, each original pixel value of the plurality of non-photographic pixels into a corresponding one converted pixel value, respectively, the non-photographic correspondence data including a first feature used to convert each original pixel value smaller than the background color value and a second feature used to convert each original pixel value greater than or equal to the background color value; generating, without determining a background color value again, photographic correspondence data by using the stored background color value without using the text color value, the photographic correspondence data being different from the non-photographic correspondence data; and converting, by using the photographic correspondence data, each original pixel value of the plurality of photographic pixels into a corresponding one converted pixel value, respectively, the photographic correspondence data including a third feature used to convert each original pixel value smaller than the background color value and the second feature, wherein a first converted pixel value, into which a specific original pixel value smaller than the background color value is converted using the first feature, is different from a second converted pixel value, into which the specific original pixel value is converted using the third feature, and wherein the second feature is used to convert each original pixel value into a corresponding one converted pixel value all have a same value, respectively.