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dlquantizationOptions

Options for quantizing a trained deep neural network

Description

The dlquantizationOptions object provides options for quantizing a trained deep neural network to scaled 8-bit integer data types. Use the dlquantizationOptions object to define the metric function to use that compares the accuracy of the network before and after quantization.

To learn about the products required to quantize a deep neural network, see Quantization Workflow Prerequisites.

Creation

Description

quantOpts = dlquantizationOptions creates a dlquantizationOptions object with default property values.

quantOpts = dlquantizationOptions(Name, Value) creates a dlquantizationOptions object with additional properties specified as Name, Value pair arguments.

Properties

expand all

Cell array of function handles specifying the functions for calculating validation metrics of quantized network.

Example: options = dlquantizationOptions('MetricFcn', {@(x)hComputeModelAccuracy(x, net, groundTruth)});

Data Types: cell

FPGA Execution Environment Options

This property affects FPGA targeting only.

Name of the FPGA bitstream specified as a character vector.

Example: 'Bitstream', 'zcu102_int8'

This property affects FPGA targeting only.

Name of the dlhdl.Target object that has the board name and board interface information.

Example: 'Target', hT

Examples

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This example shows how to quantize learnable parameters in the convolution layers of a neural network, and explore the behavior of the quantized network. In this example, you quantize the squeezenet neural network after retraining the network to classify new images according to the Train Deep Learning Network to Classify New Images example. In this example, the memory required for the network is reduced approximately 75% through quantization while the accuracy of the network is not affected.

Load the pretrained network.

net
net = 

  DAGNetwork with properties:

         Layers: [68x1 nnet.cnn.layer.Layer]
    Connections: [75x2 table]
     InputNames: {'data'}
    OutputNames: {'new_classoutput'}

Define calibration and validation data to use for quantization.

The calibration data is used to collect the dynamic ranges of the weights and biases in the convolution and fully connected layers of the network and the dynamic ranges of the activations in all layers of the network. For the best quantization results, the calibration data must be representative of inputs to the network.

The validation data is used to test the network after quantization to understand the effects of the limited range and precision of the quantized convolution layers in the network.

In this example, use the images in the MerchData data set. Define an augmentedImageDatastore object to resize the data for the network. Then, split the data into calibration and validation data sets.

unzip('MerchData.zip');
imds = imageDatastore('MerchData', ...
    'IncludeSubfolders',true, ...
    'LabelSource','foldernames');
[calData, valData] = splitEachLabel(imds, 0.7, 'randomized');
aug_calData = augmentedImageDatastore([227 227], calData);
aug_valData = augmentedImageDatastore([227 227], valData);

Create a dlquantizer object and specify the network to quantize.

quantObj = dlquantizer(net);

Define a metric function to use to compare the behavior of the network before and after quantization. Save this function in a local file.

function accuracy = hComputeModelAccuracy(predictionScores, net, dataStore)
%% Computes model-level accuracy statistics
    
    % Load ground truth
    tmp = readall(dataStore);
    groundTruth = tmp.response;
    
    % Compare with predicted label with actual ground truth 
    predictionError = {};
    for idx=1:numel(groundTruth)
        [~, idy] = max(predictionScores(idx,:)); 
        yActual = net.Layers(end).Classes(idy);
        predictionError{end+1} = (yActual == groundTruth(idx)); %#ok
    end
    
    % Sum all prediction errors.
    predictionError = [predictionError{:}];
    accuracy = sum(predictionError)/numel(predictionError);
end

Specify the metric function in a dlquantizationOptions object.

quantOpts = dlquantizationOptions('MetricFcn', ...
    {@(x)hComputeModelAccuracy(x, net, aug_valData)});

Use the calibrate function to exercise the network with sample inputs and collect range information. The calibrate function exercises the network and collects the dynamic ranges of the weights and biases in the convolution and fully connected layers of the network and the dynamic ranges of the activations in all layers of the network. The function returns a table. Each row of the table contains range information for a learnable parameter of the optimized network.

calResults = calibrate(quantObj, aug_calData)
calResults =

  95x5 table

                   Optimized Layer Name                      Network Layer Name        Learnables / Activations     MinValue      MaxValue  
    __________________________________________________    _________________________    ________________________    __________    ___________

    {'conv1_relu_conv1_Weights'                      }    {'relu_conv1'           }         "Weights"                -0.91985        0.88489
    {'conv1_relu_conv1_Bias'                         }    {'relu_conv1'           }         "Bias"                   -0.07925        0.26343
    {'fire2-squeeze1x1_fire2-relu_squeeze1x1_Weights'}    {'fire2-relu_squeeze1x1'}         "Weights"                   -1.38         1.2477
    {'fire2-squeeze1x1_fire2-relu_squeeze1x1_Bias'   }    {'fire2-relu_squeeze1x1'}         "Bias"                   -0.11641        0.24273
    {'fire2-expand1x1_fire2-relu_expand1x1_Weights'  }    {'fire2-relu_expand1x1' }         "Weights"                 -0.7406        0.90982
    {'fire2-expand1x1_fire2-relu_expand1x1_Bias'     }    {'fire2-relu_expand1x1' }         "Bias"                  -0.060056        0.14602
    {'fire2-expand3x3_fire2-relu_expand3x3_Weights'  }    {'fire2-relu_expand3x3' }         "Weights"                -0.74397        0.66905
    {'fire2-expand3x3_fire2-relu_expand3x3_Bias'     }    {'fire2-relu_expand3x3' }         "Bias"                  -0.051778       0.074239
    {'fire3-squeeze1x1_fire3-relu_squeeze1x1_Weights'}    {'fire3-relu_squeeze1x1'}         "Weights"                -0.77263        0.68897
    {'fire3-squeeze1x1_fire3-relu_squeeze1x1_Bias'   }    {'fire3-relu_squeeze1x1'}         "Bias"                   -0.10141        0.32678
    {'fire3-expand1x1_fire3-relu_expand1x1_Weights'  }    {'fire3-relu_expand1x1' }         "Weights"                -0.72131        0.97287
    {'fire3-expand1x1_fire3-relu_expand1x1_Bias'     }    {'fire3-relu_expand1x1' }         "Bias"                  -0.067043        0.30424
    {'fire3-expand3x3_fire3-relu_expand3x3_Weights'  }    {'fire3-relu_expand3x3' }         "Weights"                -0.61196        0.77431
    {'fire3-expand3x3_fire3-relu_expand3x3_Bias'     }    {'fire3-relu_expand3x3' }         "Bias"                  -0.053612        0.10329
    {'fire4-squeeze1x1_fire4-relu_squeeze1x1_Weights'}    {'fire4-relu_squeeze1x1'}         "Weights"                -0.74145         1.0888
    {'fire4-squeeze1x1_fire4-relu_squeeze1x1_Bias'   }    {'fire4-relu_squeeze1x1'}         "Bias"                   -0.10886        0.13882
...

Use the validate function to quantize the learnable parameters in the convolution layers of the network and exercise the network. The function uses the metric function defined in the dlquantizationOptions object to compare the results of the network before and after quantization.

valResults = validate(quantObj, aug_valData, quantOpts)
valResults = 

  struct with fields:

       NumSamples: 20
    MetricResults: [1x1 struct]

Examine the MetricResults.Result field of the validation output to see the performance of the quantized network.

valResults.MetricResults.Result
ans =

  2x3 table

    NetworkImplementation    MetricOutput    LearnableParameterMemory(bytes)
    _____________________    ____________    _______________________________

     {'Floating-Point'}           1                    2.9003e+06           
     {'Quantized'     }           1                    7.3393e+05           

In this example, the memory required for the network was reduced approximately 75% through quantization. The accuracy of the network is not affected.

The weights, biases, and activations of the convolution layers of the network specified in the dlquantizer object now use scaled 8-bit integer data types.

This example shows how to quantize learnable parameters in the convolution layers of a neural network, and explore the behavior of the quantized network. In this example, you quantize the LogoNet neural network. Quantization helps reduce the memory requirement of a deep neural network by quantizing weights, biases and activations of network layers to 8-bit scaled integer data types. Use MATLAB® to retrieve the prediction results from the target device.

To run this example, you need the products listed under FPGA in Quantization Workflow Prerequisites.

For additional requirements, see Quantization Workflow Prerequisites.

Create a file in your current working directory called getLogoNetwork.m. Enter these lines into the file:

function net = getLogoNetwork()
    data = getLogoData();
    net  = data.convnet;
end

function data = getLogoData()
    if ~isfile('LogoNet.mat')
        url = 'https://www.mathworks.com/supportfiles/gpucoder/cnn_models/logo_detection/LogoNet.mat';
        websave('LogoNet.mat',url);
    end
    data = load('LogoNet.mat');
end

Load the pretrained network.

snet = getLogoNetwork();
snet = 

  SeriesNetwork with properties:

         Layers: [22×1 nnet.cnn.layer.Layer]
     InputNames: {'imageinput'}
    OutputNames: {'classoutput'}

Define calibration and validation data to use for quantization.

The calibration data is used to collect the dynamic ranges of the weights and biases in the convolution and fully connected layers of the network and the dynamic ranges of the activations in all layers of the network. For the best quantization results, the calibration data must be representative of inputs to the network.

The validation data is used to test the network after quantization to understand the effects of the limited range and precision of the quantized convolution layers in the network.

This example uses the images in the logos_dataset data set. Define an augmentedImageDatastore object to resize the data for the network. Then, split the data into calibration and validation data sets.

curDir = pwd;
newDir = fullfile(matlabroot,'examples','deeplearning_shared','data','logos_dataset.zip');
copyfile(newDir,curDir);
unzip('logos_dataset.zip');
imageData = imageDatastore(fullfile(curDir,'logos_dataset'),...
 'IncludeSubfolders',true,'FileExtensions','.JPG','LabelSource','foldernames');
[calibrationData, validationData] = splitEachLabel(imageData, 0.5,'randomized');

Create a dlquantizer object and specify the network to quantize.

dlQuantObj = dlquantizer(snet,'ExecutionEnvironment','FPGA');

Use the calibrate function to exercise the network with sample inputs and collect range information. The calibrate function exercises the network and collects the dynamic ranges of the weights and biases in the convolution and fully connected layers of the network and the dynamic ranges of the activations in all layers of the network. The function returns a table. Each row of the table contains range information for a learnable parameter of the optimized network.

 dlQuantObj.calibrate(calibrationData)
ans = 
        Optimized Layer Name        Network Layer Name    Learnables / Activations     MinValue       MaxValue 
    ____________________________    __________________    ________________________    ___________    __________

    {'conv_1_Weights'          }      {'conv_1'    }           "Weights"                -0.048978      0.039352
    {'conv_1_Bias'             }      {'conv_1'    }           "Bias"                     0.99996        1.0028
    {'conv_2_Weights'          }      {'conv_2'    }           "Weights"                -0.055518      0.061901
    {'conv_2_Bias'             }      {'conv_2'    }           "Bias"                 -0.00061171       0.00227
    {'conv_3_Weights'          }      {'conv_3'    }           "Weights"                -0.045942      0.046927
    {'conv_3_Bias'             }      {'conv_3'    }           "Bias"                  -0.0013998     0.0015218
    {'conv_4_Weights'          }      {'conv_4'    }           "Weights"                -0.045967         0.051
    {'conv_4_Bias'             }      {'conv_4'    }           "Bias"                    -0.00164     0.0037892
    {'fc_1_Weights'            }      {'fc_1'      }           "Weights"                -0.051394      0.054344
    {'fc_1_Bias'               }      {'fc_1'      }           "Bias"                 -0.00052319    0.00084454
    {'fc_2_Weights'            }      {'fc_2'      }           "Weights"                 -0.05016      0.051557
    {'fc_2_Bias'               }      {'fc_2'      }           "Bias"                  -0.0017564     0.0018502
    {'fc_3_Weights'            }      {'fc_3'      }           "Weights"                -0.050706       0.04678
    {'fc_3_Bias'               }      {'fc_3'      }           "Bias"                    -0.02951      0.024855
    {'imageinput'              }      {'imageinput'}           "Activations"                    0           255
    {'imageinput_normalization'}      {'imageinput'}           "Activations"              -139.34        198.72

Create a target object with a custom name for your target device and an interface to connect your target device to the host computer. Interface options are JTAG and Ethernet. To create the target object, enter:

hTarget = dlhdl.Target('Intel', 'Interface', 'JTAG');

Define a metric function to use to compare the behavior of the network before and after quantization. Save this function in a local file.

function accuracy = hComputeAccuracy(predictionScores, net, dataStore)
%% hComputeAccuracy test helper function computes model level accuracy statistics

% Copyright 2020 The MathWorks, Inc.
    
    % Load ground truth 
    groundTruth = dataStore.Labels;
    
    % Compare with predicted label with actual ground truth 
    predictionError = {};
    for idx=1:numel(groundTruth)
        [~, idy] = max(predictionScores(idx, :)); 
        yActual = net.Layers(end).Classes(idy);
        predictionError{end+1} = (yActual == groundTruth(idx)); %#ok
    end
    
    % Sum all prediction errors.
    predictionError = [predictionError{:}];
    accuracy = sum(predictionError)/numel(predictionError);
end

Specify the metric function in a dlquantizationOptions object.

options = dlquantizationOptions('MetricFcn', ...
    {@(x)hComputeModelAccuracy(x, snet, validationData)},'Bitstream','arria10soc_int8',...
'Target',hTarget);

To compile and deploy the quantized network, run the validate function of the dlquantizer object. Use the validate function to quantize the learnable parameters in the convolution layers of the network and exercise the network. This function uses the output of the compile function to program the FPGA board by using the programming file. It also downloads the network weights and biases. The deploy function checks for the Intel Quartus tool and the supported tool version. It then starts programming the FPGA device by using the sof file, displays progress messages, and the time it takes to deploy the network. The function uses the metric function defined in the dlquantizationOptions object to compare the results of the network before and after quantization.

prediction = dlQuantObj.validate(validationData,options);
           offset_name          offset_address     allocated_space 
    _______________________    ______________    _________________

    "InputDataOffset"           "0x00000000"     "48.0 MB"        
    "OutputResultOffset"        "0x03000000"     "4.0 MB"         
    "SystemBufferOffset"        "0x03400000"     "60.0 MB"        
    "InstructionDataOffset"     "0x07000000"     "8.0 MB"         
    "ConvWeightDataOffset"      "0x07800000"     "8.0 MB"         
    "FCWeightDataOffset"        "0x08000000"     "12.0 MB"        
    "EndOffset"                 "0x08c00000"     "Total: 140.0 MB"

### Programming FPGA Bitstream using JTAG...
### Programming the FPGA bitstream has been completed successfully.
### Loading weights to Conv Processor.
### Conv Weights loaded. Current time is 16-Jul-2020 12:45:10
### Loading weights to FC Processor.
### FC Weights loaded. Current time is 16-Jul-2020 12:45:26
### Finished writing input activations.
### Running single input activations.


              Deep Learning Processor Profiler Performance Results

                   LastLayerLatency(cycles)   LastLayerLatency(seconds)       FramesNum      Total Latency     Frames/s
                         -------------             -------------              ---------        ---------       ---------
Network                   13570959                  0.09047                      30          380609145             11.8
    conv_module           12667786                  0.08445 
        conv_1             3938907                  0.02626 
        maxpool_1          1544560                  0.01030 
        conv_2             2910954                  0.01941 
        maxpool_2           577524                  0.00385 
        conv_3             2552707                  0.01702 
        maxpool_3           676542                  0.00451 
        conv_4              455434                  0.00304 
        maxpool_4            11251                  0.00008 
    fc_module               903173                  0.00602 
        fc_1                536164                  0.00357 
        fc_2                342643                  0.00228 
        fc_3                 24364                  0.00016 
 * The clock frequency of the DL processor is: 150MHz


### Finished writing input activations.
### Running single input activations.


              Deep Learning Processor Profiler Performance Results

                   LastLayerLatency(cycles)   LastLayerLatency(seconds)       FramesNum      Total Latency     Frames/s
                         -------------             -------------              ---------        ---------       ---------
Network                   13570364                  0.09047                      30          380612682             11.8
    conv_module           12667103                  0.08445 
        conv_1             3939296                  0.02626 
        maxpool_1          1544371                  0.01030 
        conv_2             2910747                  0.01940 
        maxpool_2           577654                  0.00385 
        conv_3             2551829                  0.01701 
        maxpool_3           676548                  0.00451 
        conv_4              455396                  0.00304 
        maxpool_4            11355                  0.00008 
    fc_module               903261                  0.00602 
        fc_1                536206                  0.00357 
        fc_2                342688                  0.00228 
        fc_3                 24365                  0.00016 
 * The clock frequency of the DL processor is: 150MHz


### Finished writing input activations.
### Running single input activations.


              Deep Learning Processor Profiler Performance Results

                   LastLayerLatency(cycles)   LastLayerLatency(seconds)       FramesNum      Total Latency     Frames/s
                         -------------             -------------              ---------        ---------       ---------
Network                   13571561                  0.09048                      30          380608338             11.8
    conv_module           12668340                  0.08446 
        conv_1             3939070                  0.02626 
        maxpool_1          1545327                  0.01030 
        conv_2             2911061                  0.01941 
        maxpool_2           577557                  0.00385 
        conv_3             2552082                  0.01701 
        maxpool_3           676506                  0.00451 
        conv_4              455582                  0.00304 
        maxpool_4            11248                  0.00007 
    fc_module               903221                  0.00602 
        fc_1                536167                  0.00357 
        fc_2                342643                  0.00228 
        fc_3                 24409                  0.00016 
 * The clock frequency of the DL processor is: 150MHz


### Finished writing input activations.
### Running single input activations.


              Deep Learning Processor Profiler Performance Results

                   LastLayerLatency(cycles)   LastLayerLatency(seconds)       FramesNum      Total Latency     Frames/s
                         -------------             -------------              ---------        ---------       ---------
Network                   13569862                  0.09047                      30          380613327             11.8
    conv_module           12666756                  0.08445 
        conv_1             3939212                  0.02626 
        maxpool_1          1543267                  0.01029 
        conv_2             2911184                  0.01941 
        maxpool_2           577275                  0.00385 
        conv_3             2552868                  0.01702 
        maxpool_3           676438                  0.00451 
        conv_4              455353                  0.00304 
        maxpool_4            11252                  0.00008 
    fc_module               903106                  0.00602 
        fc_1                536050                  0.00357 
        fc_2                342645                  0.00228 
        fc_3                 24409                  0.00016 
 * The clock frequency of the DL processor is: 150MHz


### Finished writing input activations.
### Running single input activations.


              Deep Learning Processor Profiler Performance Results

                   LastLayerLatency(cycles)   LastLayerLatency(seconds)       FramesNum      Total Latency     Frames/s
                         -------------             -------------              ---------        ---------       ---------
Network                   13570823                  0.09047                      30          380619836             11.8
    conv_module           12667607                  0.08445 
        conv_1             3939074                  0.02626 
        maxpool_1          1544519                  0.01030 
        conv_2             2910636                  0.01940 
        maxpool_2           577769                  0.00385 
        conv_3             2551800                  0.01701 
        maxpool_3           676795                  0.00451 
        conv_4              455859                  0.00304 
        maxpool_4            11248                  0.00007 
    fc_module               903216                  0.00602 
        fc_1                536165                  0.00357 
        fc_2                342643                  0.00228 
        fc_3                 24406                  0.00016 
 * The clock frequency of the DL processor is: 150MHz


          offset_name          offset_address     allocated_space 
    _______________________    ______________    _________________

    "InputDataOffset"           "0x00000000"     "48.0 MB"        
    "OutputResultOffset"        "0x03000000"     "4.0 MB"         
    "SystemBufferOffset"        "0x03400000"     "60.0 MB"        
    "InstructionDataOffset"     "0x07000000"     "8.0 MB"         
    "ConvWeightDataOffset"      "0x07800000"     "8.0 MB"         
    "FCWeightDataOffset"        "0x08000000"     "12.0 MB"        
    "EndOffset"                 "0x08c00000"     "Total: 140.0 MB"

### FPGA bitstream programming has been skipped as the same bitstream is already loaded on the target FPGA.
### Deep learning network programming has been skipped as the same network is already loaded on the target FPGA.
### Finished writing input activations.
### Running single input activations.


              Deep Learning Processor Profiler Performance Results

                   LastLayerLatency(cycles)   LastLayerLatency(seconds)       FramesNum      Total Latency     Frames/s
                         -------------             -------------              ---------        ---------       ---------
Network                   13572329                  0.09048                      10          127265075             11.8
    conv_module           12669135                  0.08446 
        conv_1             3939559                  0.02626 
        maxpool_1          1545378                  0.01030 
        conv_2             2911243                  0.01941 
        maxpool_2           577422                  0.00385 
        conv_3             2552064                  0.01701 
        maxpool_3           676678                  0.00451 
        conv_4              455657                  0.00304 
        maxpool_4            11227                  0.00007 
    fc_module               903194                  0.00602 
        fc_1                536140                  0.00357 
        fc_2                342688                  0.00228 
        fc_3                 24364                  0.00016 
 * The clock frequency of the DL processor is: 150MHz


### Finished writing input activations.
### Running single input activations.


              Deep Learning Processor Profiler Performance Results

                   LastLayerLatency(cycles)   LastLayerLatency(seconds)       FramesNum      Total Latency     Frames/s
                         -------------             -------------              ---------        ---------       ---------
Network                   13572527                  0.09048                      10          127266427             11.8
    conv_module           12669266                  0.08446 
        conv_1             3939776                  0.02627 
        maxpool_1          1545632                  0.01030 
        conv_2             2911169                  0.01941 
        maxpool_2           577592                  0.00385 
        conv_3             2551613                  0.01701 
        maxpool_3           676811                  0.00451 
        conv_4              455418                  0.00304 
        maxpool_4            11348                  0.00008 
    fc_module               903261                  0.00602 
        fc_1                536205                  0.00357 
        fc_2                342689                  0.00228 
        fc_3                 24365                  0.00016 
 * The clock frequency of the DL processor is: 150MHz

Examine the MetricResults.Result field of the validation output to see the performance of the quantized network.

validateOut = prediction.MetricResults.Result
ans = 
    NetworkImplementation    MetricOutput
    _____________________    ____________

     {'Floating-Point'}         0.9875   
     {'Quantized'     }         0.9875   

Examine the QuantizedNetworkFPS field of the validation output to see the frames per second performance of the quantized network.

prediction.QuantizedNetworkFPS
ans = 11.8126

The weights, biases, and activations of the convolution layers of the network specified in the dlquantizer object now use scaled 8-bit integer data types.

Introduced in R2020a