Methods and systems for characterizing regions of substantially-uniform color in a digital image

An image-processing apparatus for determining an image characteristic in a digital image, said image-processing apparatus comprising:

• a) in a computing system comprising at least one computing device, a first selector for determining a first plurality of pixels in a digital image;
• b) in said computing system, a first histogram generator for determining a first histogram of values of a first-channel for said first plurality of pixels;
• c) in said computing system, a first peak identifier for identifying, from only data in said first histogram, a first peak in said first histogram, wherein said first peak identifier identifies a first-channel starting value and a first-channel ending value;
• d) in said computing system, a second histogram generator for determining a second histogram of values of a second-channel for a second plurality of pixels in said digital image, wherein said second plurality of pixels is limited to pixels, from said first plurality of pixels, with a first-channel value between said first-channel starting value and said first-channel ending value;
• e) in said computing system, a second peak identifier for identifying, from only data in said second histogram, a second peak in said second histogram;
• and
• f) in said computing system, a characteristic generator for identifying a characteristic of said image with said first peak and said second peak.

A non-transitory computer readable medium encoded with a computer program code for implementing a method for determining a page background color in a digital image, said method comprising:

• a) determining a first plurality of pixels in a digital image;
• b) determining a first histogram of values of a first-channel for said first plurality of pixels;
• c) identifying, from only data in said first histogram, a first peak in said first histogram, wherein said first peak is identified by a first-channel starting value and a first-channel ending value;
• d) determining a second histogram of values of a second-channel for a second plurality of pixels, wherein said second plurality of pixels is limited to pixels in said first plurality of pixels with a first-channel value between said first-channel starting value and said first-channel ending value;
• e) determining a third histogram of values of a third-channel for said second plurality of pixels;
• f) identifying, from only data in said second histogram, a second peak in said second histogram, wherein said second peak is identified by a second-channel starting value and a second-channel ending value;
• g) identifying, from only data in said third histogram, a third peak in said third histogram, wherein said third peak is identified by a third-channel starting value and a third-channel ending value;
• and
• h) determining a page background color, wherein said page background color is based on said first peak, said second peak and said third peak.