Methods of collecting photometric image data and determining light exposure by extracting feature image data from an original image

A method of determining light exposure comprising the steps of:

• reading information in relation to a color original image and dividing said color original image into a plurality of picture elements to analyze respective ones of the picture elements with respect to three colors of light for photometry, said information being at least one of size information representing a size of a main image and region information representing an image region in which said main image is formed, and said at least one of said size information and said region information being recorded or stored by a photographing apparatus during photography;
• generating a histogram in relation to hue value depending upon data obtained from said photometry and dividing said histogram into portions each containing a crest of said histogram;
• deciding to which of said crests said respective picture elements of said color original image belong so as to distribute each of said picture elements into a corresponding cluster, and analyzing said color original image for each cluster;
• selecting a region of said color original image, which corresponds to said information, as a feature image region;
• and
• determining said light exposure for copy material depending upon photometric image data obtained from said feature image region.

A method of determining light exposure comprising the steps of:

• reading information in relation to a color original image and dividing said color original image into a plurality of picture elements to analyze respective ones of said picture elements with respect to three colors of light for photometry, said information being any one of size information representing a size of a main image and size related information for finding a size of said main image;
• generating a two-dimensional histogram in relation to hue value and saturation value depending upon data obtained by said photometry and dividing said two-dimensional histogram into portions each containing a crest;
• deciding to which of said crests said respective picture elements of said color original image belong so as to distribute each of said picture elements into a corresponding cluster, and analyzing said color original image for each cluster;
• selecting a region of said color original image, which corresponds to said information, as a feature image region;
• and
• determining said light exposure for copy material depending upon photometric image data obtained from said feature image region.

A method of determining light exposure in which a color original image is divided into many picture elements, said picture elements are analyzed with respect to three colors of light by picture elements for photometry, and said light exposure for copying said color original image to copy material is determined depending upon photometrical image data, said method comprising the steps of:

• determining a size of one picture element depending upon information in relation to a size of a main image so as to collect image data;
• classifying said collected image data into one or more clusters having any one of a same or similar hue value, and the same or similar hue value and a same or similar saturation value;
• finding an image feature amount from said image data of a region in a vicinity of each region of said color original image so as to correspond to each of said one or more clusters as classified;
• determining a main image region from said found image feature amount;
• and
• determining said light exposure to copy material depending upon said image data of said determined main image region.

A method of determining light exposure comprising the steps of:

• classifying a region having adjacent picture elements including similar color data as one cluster depending upon data obtained by photometry, and analyzing an original color image for each cluster;
• selecting a region of said color original image, which corresponds to information of a main image of the color image;
• estimating a main image size depending upon said information, and the steps of classifying, selecting, and determining are carried out only when said main image size is within a predetermined range of sizes;
• and
• determining said light exposure for copy material depending upon photometric image data obtained from said feature image region.