Image processing apparatus that executes halftone process on target image data including edge pixel

A non-transitory computer readable storage medium storing a set of program instructions for an image processing apparatus, the image processing apparatus including a processor, the program instructions, when executed by the processor, causing the image processing apparatus to perform:

• specifying input image data;
• executing a halftone process onto target image data to thereby generate processed data, the target image data being obtained based on the input image data and representing a target image in which a plurality of pixels are arranged, the target image data including a colorant-corresponding gradation value for each of the plurality of pixels, the colorant-corresponding gradation value for each pixel being defined for a color component corresponding to colorant and representing density of the color component in color of the each pixel, the processed data representing a dot formation state for each pixel;
• and
• supplying the processed data to a print execution section that is configured to print images by using the colorant,
• the executing the halftone process including:
• judging whether a target pixel among the plurality of pixels is an edge pixel representative of an edge of an object in the target image;
• executing a first judgement to determine whether a density index value for the target pixel is greater than a threshold value, the density index value for the target pixel being related to the density of the color component in the color of the target pixel that is represented by the colorant-corresponding gradation value for the target pixel;
• in a case where a dot forming condition is not satisfied, executing a first dot formation determination the dot forming condition including a condition that the target pixel is an edge pixel and another condition that the density index value is greater than the threshold value, the first dot formation determination being configured to determine whether to form a dot for the target pixel dependently on the colorant-corresponding gradation value for the target pixel and according to a predetermined method;
• and
• in a case where the dot forming condition is satisfied, executing a second dot formation determination to determine that a dot is to be formed for the target pixel, irrespective of the colorant-corresponding gradation value for the target pixel.

An image processing method comprising:

• specifying input image data;
• executing a halftone process onto target image data to thereby generate processed data, the target image data being obtained based on the input image data and representing a target image in which a plurality of pixels are arranged, the target image data including a colorant-corresponding gradation value for each of the plurality of pixels, the colorant-corresponding gradation value for each pixel being defined for a color component corresponding to colorant and representing density of the color component in color of the each pixel, the processed data representing a dot formation state for each pixel;
• and
• supplying the processed data to a print execution section that is configured to print images by using the colorant,
• the executing the halftone process including:
• judging whether a target pixel among the plurality of pixels is an edge pixel representative of an edge of an object in the target image;
• executing a first judgement to determine whether a density index value for the target pixel is greater than a threshold value, the density index value for the target pixel being related to the density of the color component in the color of the target pixel that is represented by the colorant-corresponding gradation value for the target pixel;
• in a case where a dot forming condition is not satisfied, executing a first dot formation determination the dot forming condition including a condition that the target pixel is an edge pixel and another condition that the density index value is greater than the threshold value, the first dot formation determination being configured to determine whether to form a dot for the target pixel dependently on the colorant-corresponding gradation value for the target pixel and according to a predetermined method;
• and
• in a case where the dot forming condition is satisfied, executing a second dot formation determination to determine that a dot is to be formed for the target pixel, irrespective of the colorant-corresponding gradation value for the target pixel.