Image processing apparatus, method for processing image, and recording medium for noise removal and skew correction

A method for processing an image comprising:

• obtaining a read image read from an image of a document output from an image reading device;
• detecting an edge between a background area and a document area in the read image;
• sampling a detection result of the edge at each first interval in a first direction to extract a first boundary point group including a plurality of boundary points;
• sampling the detection result of the edge at each second interval in the first direction to extract a second boundary point group including a plurality of boundary points;
• determining a noise removal condition based on the first boundary point group;
• removing, from the second boundary point group, a boundary point satisfying the noise removal condition as noise;
• and
• calculating a linear equation approximating the second boundary point group from which the noise is removed.

A non-transitory recording medium which, when executed by one or more processors, cause the processors to perform a method for processing an image comprising:

• obtaining a read image read from an image of a document output from an image reading device;
• detecting an edge between a background area and a document area in the read image;
• sampling a detection result of the edge at each first interval in a first direction to extract a first boundary point group including a plurality of boundary points;
• sampling the detection result of the edge at each second interval in the first direction to extract a second boundary point group including a plurality of boundary points;
• determining a noise removal condition based on the first boundary point group;
• removing, from the second boundary point group, a boundary point satisfying the noise removal condition as noise;
• and
• calculating a linear equation approximating the second boundary point group from which the noise is removed.