Image processing apparatus, image forming apparatus, image processing method, computer program and computer-readable medium

An image forming apparatus, comprising:

• an image processing apparatus that extracts from an input image data a foreground pixel configuring a foreground image of the input image data;
• and
• an image compression unit that compresses by a method a foreground pixel image data extracted from the input image data by the image processing apparatus and compresses by another method a pixel image data other than the foreground pixel, wherein
• the method is different from said another method, and
• the image processing apparatus comprises:
• a foreground extracting section having:
• an uniform density pixel block extracting portion that segments the input image data into plural pixel blocks, and extracts an uniform density pixel block in which a pixel value difference of pixels is less than a predetermined value among the plural pixel blocks;
• a background dominant color calculating portion that calculates a background dominant color based on a pixel value in the uniform density pixel block extracted by the uniform density pixel block extracting portion;
• a foreground-pixel block determining portion that compares the background dominant color calculated by the background dominant color calculating portion and a pixel value in a target pixel block, determines whether or not the target pixel block is a foreground pixel block configuring the foreground image, and generates a foreground pixel-block mask based on the pixel block determined to be the foreground pixel block;
• and a foreground dominant-color calculating portion that calculates a foreground dominant color based on a pixel value in the foreground pixel block determined by the foreground-pixel block determining portion;
• a layout analysis processing section having:
• a foreground region extracting portion that extracts a foreground region configured with sequential foreground pixel blocks, based on the foreground pixel-block mask generated by the foreground-pixel block determining portion, and generates a foreground information regarding the extracted foreground region;
• an adjacent foreground distance direction calculating portion that calculates a distance of the foreground regions extracted by foreground region extracting portion and directions of the foreground regions extracted by foreground region extracting portion;
• and a text string region extracting portion that extracts a text string configured with the foreground regions, based on the distance and directions calculated by the adjacent-foreground distance direction calculating portion;
• and
• a foreground-pixel extracting section that extracts from the input image data the foreground pixel based on the background dominant color, the foreground dominant color and the extracted text string region by the text string region extracting portion.

A non-transitory computer-readable medium that records a computer program for making a computer extract from an input image data a foreground pixel configuring a foreground image of the input image data, wherein the computer program when executed causes the computer to execute:

• segmenting the input image data into plural pixel blocks;
• extracting an uniform density pixel block in which a pixel value difference of pixels is less than a predetermined value among the plural pixel blocks;
• calculating a background dominant color based on a pixel value in the extracted uniform density pixel block;
• comparing the calculated background dominant color and a pixel value in a target pixel block, determining whether or not the target pixel block is a foreground pixel block configuring the foreground image, and generating a foreground pixel-block mask based on the pixel block determined to be the foreground pixel block;
• calculating a foreground dominant color based on a pixel value in the determined foreground pixel block;
• extracting a foreground region configured with sequential foreground pixel blocks, based on the generated foreground pixel-block mask, and generating a foreground information regarding the extracted foreground region;
• calculating a distance of the extracted foreground regions and directions of the extracted foreground regions;
• extracting a text string configured with the foreground regions, based on the calculated distance and directions;
• and
• extracting from the input image data the foreground pixel based on the background dominant color, the foreground dominant color and the extracted text string region.