Image processing apparatus and image processing method

Abstract

An image processing apparatus comprises a processor for quantizing multi-gradation image data with regard to each of R, G and B to convert it into pseudo halftone output image data. First, the processor performs a first quantization for deciding a dot appearance pattern C (B)i,j [k] with respect to an observed pixel of the multi-gradation image data with regard to blue. After that, the processor performs a second quantization for deciding the dot appearance pattern of green with respect to the observed pixel so as to make an anti-correlation with the dot appearance pattern C (B)i,j [k] decided by the first quantization.

1 . An image processing apparatus comprising a processor for performing: 
 a first quantization for deciding a dot appearance information array with respect to an observed pixel of multi-gradation image data with regard to a first color of a plurality of colors different from each other; and    a second quantization for deciding a dot appearance information array so as to make an anti-correlation with the dot appearance information array decided by the first quantization to be high, with respect to the observed pixel of multi-gradation image data with regard to a second color other than the first color of the plurality of colors different from each other, after the first quantization is performed,    when the multi-gradation image data with regard to each of the plurality of colors different from each other are quantized and converted into pseudo halftone output image data.    
   
   
       2 . The image processing apparatus of  claim 1 , wherein an anti-correlation of the dot appearance information array with respect to the observed pixel, which is decided by the first quantization, with a dot appearance information array with respect to a neighboring pixel of the observed pixel, to which the first quantization is already performed, is substantially the highest.  
   
   
       3 . The image processing apparatus of  claim 1 , wherein the processor decides the dot appearance information array so as to make an anti-correlation with the dot appearance information array decided by the first quantization, to which a predetermined weighting is performed, to be high, in the second quantization.  
   
   
       4 . The image processing apparatus of  claim 1 , wherein the processor performs a third quantization for deciding a dot appearance information array so as to make an anti-correlation with the dot appearance information decided by at least one of the first quantization and the second quantization, with respect to the observed pixel of the multi-gradation image data with regard to a third color other than the first color and the second color of the plurality of colors, after the second quantization is performed.  
   
   
       5 . The image processing apparatus of  claim 1 , wherein lightness of the first color is lower than lightness of the second color.  
   
   
       6 . The image processing apparatus of  claim 1 , wherein the first color is blue and the second color is red or green.  
   
   
       7 . The image processing apparatus of  claim 1 , wherein the first color is black and the second color is magenta or cyan.  
   
   
       8 . The image processing apparatus of  claim 1 , wherein the processor calculates an expectation value of an appearance of a dot in a neighboring pixel of the observed pixel, for every element number of an element composing the dot appearance information array with respect to the neighboring pixel of the observed pixel, and adds a random value to the calculated expectation value.  
   
   
       9 . The image processing apparatus of  claim 1 , wherein the processor performs the quantization for deciding the dot appearance information array so as to make the anti-correlation with the dot appearance information array with respect to a neighboring pixel, to which the quantization is already performed, of the observed pixel of the multi-gradation image data, to be high, after a random value is added to a gradation value of the observed pixel.  
   
   
       10 . The image processing apparatus of  claim 1 , wherein the processor controls 
 performing an arrangement of a dot of which an occupancy rate per unit area is low, after performing an arrangement of a dot of which the occupancy rate per unit area is high, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and a summation of the occupancy rates of dots is not more than 100%, in the multi-gradation image data, and    performing the arrangement of the dot of which the occupancy rate per unit area is high, after performing the arrangement of the dot of which the occupancy rate per unit area is low, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and the summation of the occupancy rates of dots is more than 100%, in the multi-gradation image data.    
   
   
       11 . An image processing method comprising: 
 performing a first quantization for deciding a dot appearance information array with respect to an observed pixel of multi-gradation image data with regard to a first color of a plurality of colors different from each other; and    performing a second quantization for deciding a dot appearance information array so as to make an anti-correlation with the dot appearance information array decided by the first quantization to be high, with respect to the observed pixel of multi-gradation image data with regard to a second color other than the first color of the plurality of colors different from each other, after the first quantization is performed,    when the multi-gradation image data with regard to each of the plurality of colors different from each other are quantized and converted into pseudo halftone output image data.    
   
   
       12 . The image processing method of  claim 11 , wherein the dot appearance information array with respect to the observed pixel is decided so as to make an anti-correlation with a dot appearance information array with respect to a neighboring pixel of the observed pixel, to which the first quantization is already performed, to be substantially the highest, in the first quantization.  
   
   
       13 . The image processing method of  claim 11 , wherein the dot appearance information array is decided so as to make an anti-correlation with the dot appearance information array previously decided by the first quantization, to which a predetermined weighting is performed, to be high, in the second quantization.  
   
   
       14 . The image processing method of  claim 11 , further comprising performing a third quantization for deciding a dot appearance information array so as to make an anti-correlation with the dot appearance information decided by at least one of the first quantization and the second quantization, to be high, with respect to the observed pixel of the multi-gradation image data with regard to a third color other than the first color and the second color of the plurality of colors, after the second quantization is performed.  
   
   
       15 . The image processing method of  claim 11 , wherein a color of which lightness is lower than lightness of the second color is selected as the first color, in the first quantization.  
   
   
       16 . The image processing method of  claim 11 , wherein blue is selected as the first color, and red or green is selected as the second color.  
   
   
       17 . The image processing method of  claim 11 , wherein black is selected as the first color, and magenta or cyan is selected as the second color.  
   
   
       18 . The image processing method of  claim 11 , wherein 
 an expectation value of an appearance of a dot in a neighboring pixel of the observed pixel is calculated for every element number of an element composing the dot appearance information array with respect to the neighboring pixel of the observed pixel; and    a random value is added to the calculated expectation value.    
   
   
       19 . The image processing method of  claim 11 , wherein the quantization for deciding the dot appearance information array is performed so as to make the anti-correlation with the dot appearance information array with respect to a neighboring pixel, to which the quantization is already performed, of the observed pixel of the multi-gradation image data, to be high, after a random value is added to a gradation value of the observed pixel.  
   
   
       20 . The image processing method of  claim 11 , wherein 
 an arrangement of a dot of which an occupancy rate per unit area is low is performed, after an arrangement of a dot of which the occupancy rate per unit area is high is performed, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and a summation of the occupancy rates of dots is not more than 100%, in the multi-gradation image data, and    the arrangement of the dot of which the occupancy rate per unit area is high is performed, after the arrangement of the dot of which the occupancy rate per unit area is low is performed, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and the summation of the occupancy rates of dots is more than 100%, in the multi-gradation image data.    
   
   
       21 . An image processing apparatus comprising a processor for performing: 
 a first quantization for deciding a dot appearance information array with respect to an observed pixel of multi-gradation image data with regard to a first density of a plurality of densities different from each other; and    a second quantization for deciding a dot appearance information array so as to make an anti-correlation with the dot appearance information array decided by the first quantization to be high, with respect to the observed pixel of multi-gradation image data with regard to a second density other than the first density of the plurality of densities different from each other, after the first quantization is performed,    When multi-gradation black-and-white image data are resolved into the multi-gradation image data comprising the plurality of densities different from each other, and then, quantized and converted into pseudo halftone output image data.    
   
   
       22 . The image processing apparatus of  claim 21 , wherein an anti-correlation of the dot appearance information array with respect to the observed pixel, which is decided by the first quantization, with a dot appearance information array with respect to a neighboring pixel of the observed pixel, to which the first quantization is already performed is substantially the highest.  
   
   
       23 . The image processing apparatus of  claim 21 , wherein the processor decides the dot appearance information array so as to make an anti-correlation with the dot appearance information array decided by the first quantization, to which a predetermined weighting is performed, to be high, in the second quantization.  
   
   
       24 . The image processing apparatus of  claim 21 , wherein the processor performs a third quantization for deciding a dot appearance information array so as to make an anti-correlation with the dot appearance information decided by at least one of the first quantization and the second quantization, with respect to the observed pixel of the multi-gradation image data with regard to a third density other than the first density and the second density of the plurality of densities, after the second quantization is performed.  
   
   
       25 . The image processing apparatus of  claim 21 , wherein lightness of the first density is lower than lightness of the second density.  
   
   
       26 . The image processing apparatus of  claim 21 , wherein the processor calculates an expectation value of an appearance of a dot in a neighboring pixel of the observed pixel, for every element number of an element composing the dot appearance information array with respect to the neighboring pixel of the observed pixel, and adds a random value to the calculated expectation value.  
   
   
       27 . The image processing apparatus of  claim 21 , wherein the processor performs the quantization for deciding the dot appearance information array so as to make the anti-correlation with the dot appearance information array with respect to a neighboring pixel, to which the quantization is already performed, of the observed pixel of the multi-gradation image data, to be high, after a random value is added to a gradation value of the observed pixel.  
   
   
       28 . The image processing apparatus of  claim 21 , wherein the processor controls 
 performing an arrangement of a dot of which an occupancy rate per unit area is low, after performing an arrangement of a dot of which the occupancy rate per unit area is high, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and a summation of the occupancy rates of dots is not more than 100%, in the multi-gradation image data, and    performing the arrangement of the dot of which the occupancy rate per unit area is high, after performing the arrangement of the dot of which the occupancy rate per unit area is low, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and the summation of the occupancy rates of dots is more than 100%, in the multi-gradation image data.    
   
   
       29 . An image processing method comprising: 
 performing a first quantization for deciding a dot appearance information array with respect to an observed pixel of multi-gradation image data with regard to a first density of a plurality of densities different from each other; and    performing a second quantization for deciding a dot appearance information array so as to make an anti-correlation with the dot appearance information array decided by the first quantization to be high, with respect to the observed pixel of multi-gradation image data with regard to a second density other than the first density of the plurality of densities different from each other, after the first quantization is performed,    When multi-gradation black-and-white image data are resolved into the multi-gradation image data comprising the plurality of densities different from each other, and then, quantized and converted into pseudo halftone output image data.    
   
   
       30 . The image processing method of  claim 29 , wherein the dot appearance information array with respect to the observed pixel is decided so as to make an anti-correlation with a dot appearance information array with respect to a neighboring pixel of the observed pixel, to which the first quantization is already performed, to be substantially the highest, in the first quantization.  
   
   
       31 . The image processing method of  claim 29 , wherein the dot appearance information array is decided so as to make an anti-correlation with the dot appearance information array previously decided by the first quantization, to which a predetermined weighting is performed, to be high, in the second quantization.  
   
   
       32 . The image processing method of  claim 29 , further comprising performing a third quantization for deciding a dot appearance information array so as to make an anti-correlation with the dot appearance information decided by at least one of the first quantization and the second quantization to be high, with respect to the observed pixel of the multi-gradation image data with regard to a third density other than the first density and the second density of the plurality of densities, after the second quantization is performed.  
   
   
       33 . The image processing method of  claim 29 , wherein a density of which lightness is lower than lightness of the second density is selected as the first density, in the first quantization.  
   
   
       34 . The image processing method of  claim 29 , wherein 
 an expectation value of an appearance of a dot in a neighboring pixel of the observed pixel is calculated for every element number of an element composing the dot appearance information array with respect to the neighboring pixel of the observed pixel; and    a random value is added to the calculated expectation value.    
   
   
       35 . The image processing method of  claim 29 , wherein the quantization for deciding the dot appearance information array is performed so as to make the anti-correlation with the dot appearance information array with respect to a neighboring pixel, to which the quantization is already performed, of the observed pixel of the multi-gradation image data, to be high, after a random value is added to a gradation value of the observed pixel.  
   
   
       36 . The image processing method of  claim 29 , wherein 
 an arrangement of a dot of which an occupancy rate per unit area is low is performed, after an arrangement of a dot of which the occupancy rate per unit area is high is performed, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and a summation of the occupancy rates of dots is not more than 100%, in the multi-gradation image data, and    the arrangement of the dot of which the occupancy rate per unit area is high is performed, after the arrangement of the dot of which the occupancy rate per unit area is low is performed, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and the summation of the occupancy rates of dots is more than 100%, in the multi-gradation image data.    
   
   
       37 . An image processing apparatus comprising a processor for: 
 calculating an expectation value of an appearance of a dot in a neighboring pixel, to which a quantization is already performed, of the observed pixel of multi-gradation image data, for every element number of an element composing the dot appearance information array with respect to the neighboring pixel; and    adding a random value to the calculated expectation value,    when the quantization for deciding the dot appearance information array is performed so as to make an anti-correlation with the dot appearance information array with respect to the neighboring pixel to be high,    in a case that the multi-gradation image data are quantized and converted into pseudo halftone output image data.    
   
   
       38 . The image processing apparatus of  claim 37 , wherein the processor sets and changes the random value according to a gradation value of each pixel.  
   
   
       39 . The image processing apparatus of  claim 37 , wherein the processor sets and changes the random value according to a position of each pixel.  
   
   
       40 . An image processing apparatus comprising a processor for performing a quantization for deciding a dot appearance information array so as to make an anti-correlation with a dot appearance information array with respect to a neighboring pixel, to which the quantization is already performed, of the observed pixel of the multi-gradation image data, to be high, after a random value is added to a gradation value of the observed pixel, 
 in a case that the multi-gradation image data are quantized and converted into pseudo halftone output image data.    
   
   
       41 . The image processing apparatus of  claim 40 , wherein the processor sets and changes the random value according to a gradation value of each pixel.  
   
   
       42 . The image processing apparatus of  claim 40 , wherein the processor sets and changes the random value according to a position of each pixel.  
   
   
       43 . An image processing method comprising: 
 calculating an expectation value of an appearance of a dot in a neighboring pixel, to which a quantization is already performed, of the observed pixel of multi-gradation image data, for every element number of an element composing the dot appearance information array with respect to the neighboring pixel; and    adding a random value to the calculated expectation value,    when the quantization for deciding the dot appearance information array is performed so as to make an anti-correlation with the dot appearance information array with respect to the neighboring pixel to be high,    in a case that the multi-gradation image data are quantized and converted into pseudo halftone output image data.    
   
   
       44 . The image processing method of  claim 43 , wherein the random value is set and changed according to a gradation value of each pixel.  
   
   
       45 . The image processing method of  claim 43 , wherein the random value is set and changed according to a position of each pixel.  
   
   
       46 . An image processing method comprising: 
 performing a quantization for deciding a dot appearance information array so as to an anti-correlation with a dot appearance information array with respect to a neighboring pixel, to which the quantization is already performed, of the observed pixel of the multi-gradation image data, to be high, after a random value is added to a gradation value of the observed pixel,    in a case that the multi-gradation image data are quantized and converted into pseudo halftone output image data.    
   
   
       47 . The image processing method of  claim 46 , wherein the random value is set and changed according to a gradation value of each pixel.  
   
   
       48 . The image processing method of  claim 46 , wherein the random value is set and changed according to a position of each pixel.  
   
   
       49 . An image processing apparatus comprising a processor for performing control of specifying a shape of a systematic dot arrangement in a highlight part of multi-gradation image data, 
 when the multi-gradation image data are quantized and converted into pseudo halftone output image data.    
   
   
       50 . The image processing apparatus of  claim 49 , wherein the processor performs control of specifying the shape of the systematic dot arrangement, by specifying generation probability of the dot arrangement in the highlight part of the multi-gradation image data.  
   
   
       51 . The image processing apparatus of  claim 50 , wherein the processor sets a value representing a different dot arrangement in a same dot appearance information array, after deciding a local filter for every value corresponding to the generation probability of the different dot arrangement to calculate an element number array according to the local filter, in an observed pixel of the multi-gradation image data.  
   
   
       52 . The image processing apparatus of  claim 51 , wherein the processor sets the value representing the dot arrangement while avoiding an element number where a value representing other dot arrangement is set.  
   
   
       53 . The image processing apparatus of  claim 52 , wherein the processor judges an output status of the observed pixel according to a status of a pixel which is already processed and the specified dot arrangement.  
   
   
       54 . The image processing apparatus of  claim 53 , wherein the processor specifies the shape of the dot arrangement by setting a coefficient, which is close to the observed pixel in a dot continuous generation direction in the local filter, to be a negative number, with respect to the pixel needed to be generated continuously.  
   
   
       55 . An image processing method comprising specifying a shape of a systematic dot arrangement in a highlight part of multi-gradation image data, 
 when the multi-gradation image data are quantized and converted into pseudo halftone output image data.    
   
   
       56 . The image processing method of  claim 55 , wherein the shape of the systematic dot arrangement is specified by specifying generation probability of the dot arrangement in the highlight part of the multi-gradation image data.  
   
   
       57 . The image processing apparatus of  claim 56 , wherein a value representing a different dot arrangement is set in a same dot appearance information array, after a local filter is decided for every value corresponding to the generation probability of the different dot arrangement to calculate an element number array according to the local filter, in an observed pixel of the multi-gradation image data.  
   
   
       58 . The image processing method of  claim 57 , wherein the value representing the dot arrangement is set while avoiding an element number where a value representing other dot arrangement is set.  
   
   
       59 . The image processing method of  claim 58 , wherein an output status of the observed pixel is judged according to a status of a pixel which is already processed and the specified dot arrangement.  
   
   
       60 . The image processing method of  claim 59 , wherein the shape of the dot arrangement is specified by setting a coefficient, which is close to the observed pixel in a dot continuous generation direction in the local filter, to be a negative number, with respect to the pixel needed to be generated continuously.  
   
   
       61 . An image processing apparatus comprising a processor controls 
 performing an arrangement of a dot of which an occupancy rate per unit area is low, after performing an arrangement of a dot of which the occupancy rate per unit area is high, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and a summation of the occupancy rates of dots is not more than 100%, in the multi-gradation image data, and    performing the arrangement of the dot of which the occupancy rate per unit area is high, after performing the arrangement of the dot of which the occupancy rate per unit area is low, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and the summation of the occupancy rates of dots is more than 100%, in the multi-gradation image data    when the multi-gradation image data are quantized and converted into pseudo halftone output image data.    
   
   
       62 . An image processing method comprising 
 performing an arrangement of a dot of which an occupancy rate per unit area is low, after performing an arrangement of a dot of which the occupancy rate per unit area is high, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and a summation of the occupancy rates of dots is not more than 100%, in the multi-gradation image data, and    performing the arrangement of the dot of which the occupancy rate per unit area is high, after performing the arrangement of the dot of which the occupancy rate per unit area is low, in a case that there are two or more kinds of dots of which the occupancy rates per unit area are different from each other and the summation of the occupancy rates of dots is more than 100%, in the multi-gradation image data    when the multi-gradation image data are quantized and converted into pseudo halftone output image data.