15. A non-transitory computer-readable medium having stored thereon instructions for identifying a complex-object in a query image, which when executed by a processor cause the processor to perform the instructions comprising of: processing at least one pixel patch from the query image with a cascade of classifiers, each successive classifier of the cascade configured to identify at least one discriminative feature in the pixel patch that characterizes a part of the complex-object; wherein each successive classifier of the cascade uses a number of discriminative features greater than a number of the discriminative features used in prior classifiers of the cascade; and selecting an additional pixel patch from the query image for processing after a last classifier of the cascade has identified the distinguishing feature, wherein the selecting is based on a known positional relationship between the part and an additional part of the complex-object.
15. A non-transitory computer-readable medium having stored thereon instructions for identifying a complex-object in a query image, which when executed by a processor cause the processor to perform the instructions comprising of: processing at least one pixel patch from the query image with a cascade of classifiers, each successive classifier of the cascade configured to identify at least one discriminative feature in the pixel patch that characterizes a part of the complex-object; wherein each successive classifier of the cascade uses a number of discriminative features greater than a number of the discriminative features used in prior classifiers of the cascade; and selecting an additional pixel patch from the query image for processing after a last classifier of the cascade has identified the distinguishing feature, wherein the selecting is based on a known positional relationship between the part and an additional part of the complex-object. 18. The non-transitory, computer-readable storage medium of claim 15 , wherein the program code is further configured to cause the processor to select a second additional pixel patch from the query image for processing after a last classifier of the cascade has identified a distinguishing feature of a second part, wherein the second additional pixel patch is selected based on a known positional relationship between the part, the second part and a third additional part of the complex object.