Computer color-matching apparatus and paint color-matching method using the apparatus

A computer color-matching method for brilliant paints which comprises executing the following steps (1) to (3):

• (1) measuring a paint film of a reference color to which a color of a paint should be adjusted through color-matching by a colorimeter to obtain color data of the reference color;
• (2) measuring the paint film of the reference color to which the color of the paint should be adjusted through color-matching by a micro-brilliance-feeling measuring device to obtain microbrilliance-feeling data of the reference color;
• and
• (3) comparing the color data and the micro-brilliance-feeling data of the reference color with color data and micro-brilliance-feeling data corresponding to paint blends previously entered in a computer, indexing the degree of matching of the color and micro-brilliance feeling of the entered paint blends, and selecting a prospective paint blend,
• wherein the method is performed by using a computer color-matching apparatus comprising:
• (A) the colorimeter, (B) the micro-brilliance-feeling measuring device, and (C) the computer in which a plurality of paint blends, color data and micro-brilliance-feeling data corresponding to each of the paint blends, and color characteristic data and micro-brilliance-feeling characteristic data of a plurality of full-color paints are entered, and in which a color-matching calculation logic using the paint blends and the data operates,
• wherein the micro-brilliance-feeling measuring device comprises:
• a light irradiation device operable to irradiate light to a paint film surface;
• a CCD camera operable to photograph the light-irradiated paint film surface;
• and
• an image analyzer operable to analyze an image photographed by the CCD camera,
• wherein the micro-brilliance-feeling device obtains a two-dimensional image of the paint film surface by the CCD camera, divides the two-dimensional image into a plurality of partitions, and measures a brightness of each of the plurality of partitions,
• wherein the brightness is a digital gradation showing a shading value of the two-dimensional image photographed by the CCD camera for each partition,
• wherein the image analyzer separately and quantitatively evaluates a glitter feeling and a particle feeling of the two-dimensional image photographed by the CCD camera,
• wherein the glitter feeling is a perception of an irregular minute brilliance produced by light regularly reflected from a brilliant pigment in the paint film, and
• wherein the particle feeling is an irregular non-oriented pattern caused by an orientation or an overlap of a brilliant pigment in the paint film containing a brilliant material when observing a sample under a lighting condition in which a brilliance feeling does not easily occur,
• wherein a total sum of brightness is obtained by totaling the brightness of each of the plurality of partitions,
• wherein an average brightness is obtained by dividing the total sum of brightness by a total number of the plurality of partitions,
• wherein a threshold is set at a value which is at least the average brightness,
• wherein the glitter feeling is evaluated on the basis of a brightness whose value is at least the threshold, and
• wherein the particle feeling is evaluated by a two-dimensional power-spectrum integral value obtained by integrating the power of a low-spatial-frequency component in accordance with a spatial frequency spectrum constituted by two-dimensional-Fourier-transforming the two-dimensional image, and normalizing the power with a DC component, the two-dimensional image photographed by the CCD camera having been divided into the plurality of partitions.

A computer color-matching method of for executing the following steps (1) to (3):

• (1) measuring a paint film of a reference color to which a paint color should be adjusted through color-matching by a colorimeter to obtain color data of the reference color;
• (2) measuring the paint film of the reference color to which the paint color should be adjusted through color-matching by a micro-brilliance-feeling measuring device to obtain micro-brilliance-feeling data of the reference color;
• and
• (3) selecting color data and micro-brilliance feeling data of at least one paint blend having the same color number as a preset color number of the reference color, and comparing the color data and the micro-brilliance-feeling data of the selected paint blend with the color data and the micro-brilliance-feeling data of the reference color, indexing the degree of matching of the color and micro-brilliance feeling of the selected paint blend, and selecting a prospective paint blend,
• wherein the method is performed by using a computer color-matching apparatus comprising:
• (A) the colorimeter, (B) the micro-brilliance-feeling measuring device, and (C) a computer in which a plurality of color numbers, paint blends corresponding to the color numbers, color data and micro-brilliance-feeling data corresponding to each of the paint blends, and color characteristic data and micro-brilliance-feeling characteristic data of a plurality of full-color paints are entered, and in which a color-matching calculation logic using the paint blends and the data operates,
• wherein the micro-brilliance-feeling measuring device comprises:
• a light irradiation device operable to irradiate light to a paint film surface;
• a CCD camera operable to photograph the light-irradiated paint film surface;
• and
• an image analyzer operable to analyze an image photographed by the CCD camera,
• wherein the micro-brilliance-feeling measuring device obtains a two-dimensional image of the paint surface by the CCD camera, divides the two-dimensional image into a plurality of partitions, and measures a brightness of each of the plurality of partitions,
• wherein the brightness is a digital gradation showing a shading value of the two-dimensional image photographed by the CCD camera for each partition, and
• wherein the image analyzer separately and quantitatively evaluates a glitter feeling and a particle feeling of the two-dimensional image photographed by the CCD camera,
• wherein the glitter feeling is a perception of an irregular minute brilliance produced by light regularly reflected from a brilliant pigment in the paint film, and
• wherein the particle feeling is an irregular non-oriented pattern caused by an orientation or an overlap of a brilliant pigment in the paint film containing a brilliant material when observing a sample under a lighting condition in which a brilliance feeling does not easily occur,
• wherein a total sum of brightness is obtained by totaling the brightness of each of the plurality of partitions,
• wherein an average brightness is obtained by dividing the total sum of brightness by a total number of the plurality of partitions,
• wherein a threshold is set at a value which is at least the average brightness,
• wherein the glitter feeling is evaluated on the basis of a brightness whose value is at least the threshold, and
• wherein the particle feeling is evaluated by a two-dimensional power-spectrum integral value obtained by integrating the power of a low-spatial-frequency component in accordance with a spatial frequency spectrum constituted by two-dimensional-Fourier-transforming the two-dimensional image, and normalizing the power with a DC component, the two-dimensional image photographed by the CCD camera having been divided into the plurality of partitions.