Method for recognizing abnormal image

An apparatus, comprising:

• a light source to illuminate an object to be scanned with light;
• a component to convert at least a portion of light reflected from the object into a plurality of scan lines;
• and
• circuitry configured to:
• select two adjacent image lines having respective level values Pi and Pi−1, each of the values Pi, and Pi−1 representing the brightness of a plurality of pixels represented by a corresponding one of the image lines;
• determine a difference between said values Pi and Pi−1;
• compare said difference between said values Pi and Pi−1 to a first threshold value;
• according to whether said difference exceeds the first threshold value, select an image line having a level value Pi+1 adjacent to said image line having the level value Pi and further select an image line having a level value Pi−2 adjacent to said image line having the level value Pi−1, each of the values Pi+1 and Pi−2 representing the brightness of a plurality of pixels represented by a corresponding one of the image lines;
• determine a difference between said values Pi+1 and Pi−2;
• and
• compare said difference between said values Pi+1 and Pi−2 to a second threshold value.

A method comprising:

• selecting two adjacent image lines having respective level values Pi and Pi−1, using a processor, the values Pi and Pi−1 each representing the brightness of a plurality of pixels represented by a corresponding one of the image lines;
• calculating a difference between said values Pi and Pi−1;
• comparing said difference between said values Pi and Pi−1 to a first threshold value;
• if said difference between said values Pi and Pi−1 is larger than said first threshold value, selecting an image line having a level value Pi+1 adjacent to said image line having the level value Pi and further selecting an image line having a level value Pi−2 adjacent to said image line having the level value Pi−1, each of the values Pi+1 and Pi+2 representing the brightness of a plurality of pixels represented by a corresponding one of the image lines;
• calculating a difference between said values Pi+1 and Pi−2;
• and
• comparing said difference between said values Pi+1 and Pi−2 to a second threshold value.

An article comprising:

• a storage medium having stored thereon instructions, that, if executed, result in:
• selecting two adjacent image lines having level values Pi and Pi−1, the level values each representing the brightness of a plurality of pixels represented by a corresponding one of the image lines;
• determining a difference between said values Pi and Pi−1;
• comparing said difference between said values Pi and Pi−1 to a first threshold value, wherein if said difference between said values Pi and Pi−1 does not exceed said first threshold value, said two adjacent image lines are determined as normal, and wherein if said difference between said values Pi and Pi−1 exceeds said first threshold value, said two adjacent image lines are determined as abnormal;
• and
• if said difference between said values Pi and Pi−1 exceeds said first threshold value, selecting an image line having a level value Pi+1 adjacent to said image line having the level value Pi and further selecting an image line having a level value Pi−2 adjacent to said image line having the level value Pi−1, each of the values Pi+1 and Pi−2 representing the brightness of a plurality of pixels represented by a corresponding one of the image lines;
• determining a difference between said values Pi+1 and Pi−2;
• and
• comparing said difference between said values Pi+1 and Pi−2 to a second threshold value.

A system, comprising:

• means for comparing first brightness indications of first adjacent image lines to determine a first variance in brightness, each first brightness indication representing a plurality of pixels associated with a corresponding one of the first image lines;
• means for determining whether the first variance exceeds a threshold value;
• according to whether the first variance exceeds the threshold value, means for selecting second image lines that are adjacent to the first adjacent image lines;
• means for comparing second brightness indications of the second image lines to determine a second variance in brightness, each second brightness indication representing a plurality of pixels associated with a corresponding one of the second image lines;
• means for determining whether a scanning abnormality has occurred according to the comparisons;
• and
• means for identifying a shading abnormality if the first variance exceeds the threshold value and the second variance does not exceed the threshold value.

An apparatus comprising:

• a light source to illuminate an object to be scanned with light;
• a component to convert at least a portion of the light representing the object into a plurality of scan lines;
• and
• circuitry configured to:
• analyze first brightness indications of first adjacent image lines to determine a first variance in brightness, each first brightness indication representing a plurality of pixels associated with a corresponding one of the first image lines;
• according to a magnitude of the first variance, select second image lines that are adjacent to the first adjacent image lines;
• analyze second brightness indications of the second image lines to determine a second variance in brightness, each second brightness indication representing a plurality of pixels associated with a corresponding one of the second image lines;
• and
• determine whether a scanning abnormality has occurred according to the comparisons, and identify a dark band abnormality if the magnitudes exceed threshold values.