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 image data representing an image; defining a plurality of determination regions in at least part of the image based on the image data; executing, for the at least part of the image, a first color conversion using a first type of parameter to generate a first converted image, the first type of parameter defining relationships between usage amounts of colorant before and after the first color conversion; determining a first estimated amount of colorant for each of the plurality of determination regions in the first converted image, the first estimated amount indicating an usage amount of colorant to be used for each of the plurality of determination regions when the first converted image is printed; judging whether or not a first condition is met, the first condition including that the first estimated amounts of colorant for all of the plurality of determination regions is smaller than or equal to respective threshold values; outputting the first converted image if the first condition is met; and executing, for the at least part of the image, a second color conversion using a second type of parameter to generate a second converted image if a second condition is met, the second condition including that the first condition is not met, the second type of parameter defining relationships between usage amounts of colorant before and after the second color conversion, the usage amount of colorant for the at least part of the image that has been converted through the second color conversion using the second type of parameter being smaller than the usage amount of colorant for the at least part of the image that has been converted through the first color conversion using the first type of parameter.