JP2004015086A5 - - Google Patents

Claims (6)

An image processing apparatus that quantizes a multi-valued color image having at least first and second color components into a number of gradations smaller than the number of gradations expressed by the multi-value using an error diffusion method. There,
Adding means for adding the error of each color component generated in the previous quantization process to the multi-value data of the first and second color components of the input pixel;
The addition result of each of the first and second color components by the adding means is input as an address, and data corresponding to each addition result is output in a range smaller than the range that each addition result can take. A one-dimensional lookup table;
Two data corresponding to the first and second color components obtained by the one-dimensional lookup table are input as multi-dimensional addresses, and a quantization result having a correlation with each color component is output. With a multi-dimensional lookup table,
The image processing apparatus, wherein the one-dimensional lookup table outputs data substantially in a range of 1/9 with respect to a possible range of the addition result input as an address.   The address space represented by the data of each color component output by the one-dimensional lookup table is a multiple of the number of gradations to be quantized for each color component output by the multi-dimensional lookup table. The image processing apparatus according to claim 1.   The first and second color components are cyan and magenta, respectively, and the number of bits of the quantization result of each color component output from the multidimensional lookup table is configured so that cyan ≧ magenta. The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus. An image processing apparatus for quantizing a multi-valued color image having at least first and second color components into a number of gradations smaller than the number of gradations expressed by the multi-value using an error diffusion method A control method,
An addition step of adding the error of each color component generated in the previous quantization process to the multi-value data of the first and second color components of the input pixel;
The addition result of each of the first and second color components in the addition step is input as an address, and a one-dimensional lookup table for outputting data corresponding to each addition result is used. A first output step for outputting data in a range less than a possible range;
Two data corresponding to the first and second color components obtained in the first output step are input as multi-dimensional addresses, and a quantization result having a correlation with each color component is output. A second output step of outputting a quantization result of each color component using a multi-dimensional lookup table,
The method according to claim 1, wherein the one-dimensional lookup table outputs data substantially in a range of 1/9 with respect to a possible range of the addition result input as an address.   The address space represented by the data of each color component output by the one-dimensional lookup table is a multiple of the number of gradations to be quantized for each color component output by the multi-dimensional lookup table. The control method of the image processing apparatus of Claim 4.   The first and second color components are cyan and magenta, respectively, and the number of bits of the quantization result of each color component output from the multidimensional lookup table is configured so that cyan ≧ magenta. 6. The method for controlling an image processing apparatus according to claim 4, wherein the image processing apparatus is controlled.