Reducing scale estimate errors in shelf images

A method comprising:

• analyzing, by executing an instruction with at least one processor, a shelf image a first time to identify matches between patterns stored in a database and objects appearing in the shelf image based on a first shelf image scale estimate of the shelf image;
• determining, by executing an instruction with the at least one processor, a second shelf image scale estimate for the shelf image based on deviation values between (a) sizes of a first set of objects detected in the shelf image and (b) a first set of the patterns matched with the first set of objects;
• and
• analyzing, by executing an instruction with the at least one processor, the shelf image a second time to identify matches between the patterns stored in the database and the objects appearing in the shelf image based on the second shelf image scale estimate.

A tangible machine readable storage medium comprising instructions that, when executed, cause a machine to at least:

• analyze a shelf image a first time using an image recognition technique to identify matches between stored patterns and objects detected in the shelf image, the shelf image having a shelf image scale estimate;
• determine a scale correction value for the shelf image scale estimate based on deviations between sizes of a first set of objects detected in the shelf image and a first set of the patterns matched with the first set of objects, the first set of the patterns including a first pattern, the first pattern having an array of pattern scale estimates;
• and
• determine a new scale estimate for the array of pattern scale estimates of the first pattern based on a size of an object matched with the first pattern and the scale correction value.