초록 ▼

A scan reading method according to this invention includes the steps of: causing a line memory to store original image data for one line; obtaining a density average value of the one-line image data or a variation rate thereof; and detecting the edge of the original by comparing the average density

A scan reading method according to this invention includes the steps of: causing a line memory to store original image data for one line; obtaining a density average value of the one-line image data or a variation rate thereof; and detecting the edge of the original by comparing the average density value or the variation rate thereof with a predetermined threshold value after finishing a scan over the original or during the scan. A scan reading method also includes the steps of: preparing a density histogram from the one line image data in the original region; optionally obtaining the average density value of the variation rate thereof; detecting the top end and terminal of the original from that value; and calculating highlight and shadow densities from the density histograms after finishing the scan over the original by use of a scanner. Based on the methods of the present invention, it is therefore possible to automatically detect the edge of the original and perform a density auto-measurement at low costs with a high accuracy with the aid of a small capacity line memory without adding a multiplicity of sensors and incorporating a large capacity buffer memory.

대표청구항 ▼

A scan reading method in an image reader for detecting an edge of an original, the image reader including a platen with the original mounted thereon, and a scanner including a light source for illuminating said original sequentially or simultaneously in a main scan direction while being relatively m

A scan reading method in an image reader for detecting an edge of an original, the image reader including a platen with the original mounted thereon, and a scanner including a light source for illuminating said original sequentially or simultaneously in a main scan direction while being relatively moved in a subscan direction substantially orthogonal to said main scan direction, wherein an image of said original is photoelectrically read at each pixel by two-dimensionally scanning said original, and detecting at least one edge of said original in said subscan direction, said method comprising the steps of: taking one-line image density data in said main scan direction of said scanner in a predetermined position in said subscan direction; averaging said one-line image density data in said main scan direction to determine an average density value of said line by: plotting said average density value in said subscan position on a density distribution chart in said subscan direction; repeating the plotting process from a subscan start point on the side of one end of said platen to a subscan end point on the side of the other end thereof in accordance with the scanning operation by said scanner; obtaining said density distribution chart in said subscan direction; searching thereafter said density distribution chart; and detecting at least one edge of said original by determining where a line having an average density value which is less than a predetermined threshold value is positioned outside of an original region.