A printing apparatus comprising: a reaction liquid application portion that applies dots of reaction liquid onto a recording medium by applying the reaction liquid to pixels in a pixel array (Mt) in which rasters in which a plurality of pixels are lined up in a first direction are lined up in a second direction which is orthogonal to the first direction; and an ink application portion that applies ink dots to the recording medium by applying ink which includes a color material that is coagulated using an action of the reaction liquid to the pixels of the pixel array, wherein the reaction liquid application portion applies the reaction liquid dots so as to be separated by one pixel or more in the first direction and the second direction, wherein the printing apparatus further comprises: a memory portion that stores mask data which indicates the plurality of pixels that are separated from each other by one or more pixels in the first direction and the second direction as a pixel candidate to which the reaction liquid is applied; and characterised by: a control portion (211, 213) which generates second dot data according to a logical product of the mask data and first dot data while generating the first dot data that indicates the pixel to which the ink dots are applied, wherein the reaction liquid application portion applies the reaction liquid dots to be separated from each other by one or more pixels in the first direction and the second direction by applying the reaction liquid to the pixel which is indicated by the second dot data, and the ink application portion applies the ink dots to the pixel which is indicated by the first dot data, wherein the control portion controls the reaction liquid application portion based on a result in which a first region in which an image of a specific pattern is printed and a second region in which an image of a pattern that is different from the specific pattern is printed are recognized, and the reaction liquid application portion applies the reaction liquid dots to the pixel which is indicated by the second dot data with respect to the first region and applies the reaction liquid dots to the pixel which is indicated by the first dot data with respect to the second region, and wherein the image of the specific pattern is a ruled line image. a reaction liquid application portion that applies dots of reaction liquid onto a recording medium by applying the reaction liquid to pixels in a pixel array (Mt) in which rasters in which a plurality of pixels are lined up in a first direction are lined up in a second direction which is orthogonal to the first direction; and an ink application portion that applies ink dots to the recording medium by applying ink which includes a color material that is coagulated using an action of the reaction liquid to the pixels of the pixel array, wherein the reaction liquid application portion applies the reaction liquid dots so as to be separated by one pixel or more in the first direction and the second direction, wherein the printing apparatus further comprises: a memory portion that stores mask data which indicates the plurality of pixels that are separated from each other by one or more pixels in the first direction and the second direction as a pixel candidate to which the reaction liquid is applied; and a control portion (211, 213) which generates second dot data according to a logical product of the mask data and first dot data while generating the first dot data that indicates the pixel to which the ink dots are applied, wherein the reaction liquid application portion applies the reaction liquid dots to be separated from each other by one or more pixels in the first direction and the second direction by applying the reaction liquid to the pixel which is indicated by the second dot data, and the ink application portion applies the ink dots to the pixel which is indicated by the first dot data, wherein the control portion controls the reaction liquid application portion based on a result in which a first region in which an image of a specific pattern is printed and a second region in which an image of a pattern that is different from the specific pattern is printed are recognized, and the reaction liquid application portion applies the reaction liquid dots to the pixel which is indicated by the second dot data with respect to the first region and applies the reaction liquid dots to the pixel which is indicated by the first dot data with respect to the second region, and wherein the image of the specific pattern is a ruled line image.