SYSTEM AND METHOD FOR END-TO-END DIFFERENTIABLE JOINT IMAGE REFINEMENT AND PERCEPTION
System and method for end-to-end differentiable joint image refinement and perception are provided. A learning machine employs an image acquisition device for acquiring a set of training raw images. A processor determines a representation of a raw image, initializes a set of image representation parameters, defines a set of analysis parameters of an image analysis network configured to process the image's representation, and jointly trains the set of representation parameters and the set of analysis parameters to optimize a combined objective function. A module for transforming pixel-values of the raw image to produce a transformed image comprising pixels of variance-stabilized values, a module for successively performing processes of soft camera projection and image projection, and a module for inverse transforming the transformed pixels are disclosed. The image projection performs multi-level spatial convolution, pooling, subsampling, and interpolation.
1 . A method of machine learning, the method comprising:
forming a learning machine, the learning machine including:
an image representation network configured to extract feature maps in an input image and map the feature maps to one or more classes, the image representation network including representation parameters;
an image analysis network coupled with the image representation network, the image analysis network configured to classify the input image, the image analysis network including analysis parameters, wherein the learning machine includes global parameters, the global parameters including the representation parameters and the analysis parameters;
jointly learning the global parameters by:
jointly training the image representation network and the image analysis network;
receiving a raw image; and
processing the raw image through the image representation network and the image analysis network with the global parameters by:
processing, using the image representation network, the raw image to produce intermediate data; and
determining, using the image representation network, a perceived classification of the raw image, by processing the intermediate data.
2 . The method of claim 1 , wherein jointly learning the global parameters further comprises:
optimizing the learning machine in a closed loop by:
backpropagating gradients across layers in the image representation network and the image analysis network.
3 . The method of claim 1 , wherein jointly learning the global parameters further comprises:
optimizing a bilevel objective function of the learning machine, wherein the bilevel objective function includes an outer objective function associated with the image analysis network and an inner objective function associated with the image representation network, the inner objective function nested within the outer objective function.
4 . The method of claim 3 , wherein optimizing the bilevel objective function further comprises:
minimizing the inner objective function; and
minimizing the outer objective function.
5 . The method of claim 1 further comprising:
jointly learning the global parameters by training in a global training model using a training database including training images; and
evaluating learned global parameters by classifying, in a perception model, test images, wherein the perception model includes the image analysis network having the learned global parameters.
6 . The method of claim 5 , wherein evaluating the learned global parameters further comprises:
selecting test images having a classification success level above a threshold; and
update the training database with selected test images.
7 . The method of claim 1 further comprising:
performing a bimodal operation of the learning machine between a first mode and a second mode, wherein:
in the first mode, the global parameters are learned; and
in a second mode, an incoming image is classified based on the latest global parameters.
8 . The method of claim 7 further comprising:
transferring learned global parameters in the first mode to the image analysis network via an activated link.
9 . The method of claim 7 , wherein performing the bimodal operation further comprises:
cyclically perform the bimodal operation by operating in the first mode in a first period of time and operating in the second mode in a second period of time.
10 . The method of claim 7 , wherein performing the bimodal operation further comprises:
operating the learning machine in the first mode in a training segment of the learning machine; and
operating the learning machine in a second mode in an operational segment of the learning machine.
11 . The method of claim 7 further comprising:
updating the global parameters periodically.
12 . The method of claim 7 further comprising:
updating the global parameters after completion of an update.
13 . The method of claim 1 further comprising:
processing, using the learning machine, a plurality of raw images to generate perceived classifications of the plurality of raw images; and
adding processed raw images and associated perceived classifications to training data of the learning machine.
14 . A learning system comprising:
at least one memory device having a computer readable instructions stored thereon; and
at least one processor coupled to the at least one memory device and configured to execute the computer readable instructions, upon execution of the computer readable instructions, the at least one processor programmed to:
form a learning machine, the learning machine including:
an image representation network configured to extract feature maps in an input image and map the feature maps to one or more classes, the image representation network including representation parameters;
an image analysis network coupled with the image representation network, the image analysis network configured to classify the input image, the image analysis network including analysis parameters, wherein the learning machine includes global parameters, the global parameters including the representation parameters and the analysis parameters; and
jointly learn the global parameters by:
jointly training the image representation network and the image analysis network.
15 . The learning system of claim 14 , wherein the at least one processor is further programmed to:
perform a bimodal operation of the learning machine between a first mode and a second mode, wherein:
in the first mode, the global parameters are learned; and
in a second mode, an incoming image is classified based on the latest global parameters.
16 . The learning system of claim 15 , wherein the at least one processor is further programmed to:
transfer learned global parameters in the first mode to the image analysis network via an activated link.
17 . The learning system of claim 14 , wherein the at least one processor is further programmed to:
jointly learn the global parameters by:
optimizing a bilevel objective function of the learning machine, wherein the bilevel objective function includes an outer objective function associated with the image analysis network and an inner objective function associated with the image representation network, the inner objective function nested within the outer objective function.
18 . The learning system of claim 14 further comprising a learning deport separate from the learning machine, wherein the learning deport includes training data and learned data, the learned data including the global parameters.
19 . The learning system of claim 18 , wherein the at least one processor is further programmed to:
process, using the learning machine, a plurality of raw images to generate perceived classifications of the plurality of raw images; and
add processed raw images and associated perceived classifications to training data.
20 . The learning system of claim 14 , wherein the image representation network includes an image representation stage, the at least one processor further programmed to:
recursively activate the image representation stage, via a feedback loop connecting an output from the image representation stage to an input of the image representation stage; and
specify the global parameters corresponding to a specific activation in recursively activated image representation stages.