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Deep learning project end to end | Potato Disease Classification - 3 : Model Building

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This content details the process of building, training, and evaluating a Convolutional Neural Network (CNN) for image classification, culminating in saving the trained model for future predictions and discussing strategies for versioning.

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In the last video we loaded our data and then

we did some pre-processing to make it

ready for model training.

In this video we are going to build a

convolutional neural network and train

that network on our trained data set

and then we'll measure the accuracy

using our test data set. If the accuracy

looks okay we will export that model to

a file on a disk so that it can be used

later on in our fast api based server

for making prediction. Let's get started!

Our data set is pre-processed and we are

ready to build the model. We are going to

use convolutional neural network which

is a famous type of neural network

architecture. If you are solving

you know image classification problem

and for that I made a video actually so

if you go to Youtube search for this

you'll find my video. I highly recommend

you watch this because there are a lot

of concepts that I'm

clearing in this video

and we are going to use this

architecture you know in our code today.

So when you have convolutional neural

network there are two parts. There are

convolutional layers so there are

convolutional and pulling layers so

pulling

there could be a number of layers

and then there is a dense layer where

you just flatten it so we are going to

follow this architecture and that

therefore I am saying you need to watch

this video if you haven't to understand

what we are doing in today's

session. So here I'm

now building

basically my model. So I'll say model is

equal to this and we will have

set of layers here. So the first layer

would be resize and rescale

whenever you feed an image first thing

will be you will resize it then you

scale it by dividing by 255,

then you do data augmentation so that

you do you know horizontal vertical

flip

random rotation to generate new samples?

The third layers is your convolutional

layer so here I will say Conv

2d.

Okay. What are the arguments

here? you can say

tensorflow conv2d layer you find a help

the first argument is number of

filters and kernel size. So this kernel

size is

basically the size of the filter so if

you looked at

this video you know I'm talking about

filters here in this video

and

the filter.. Let's see

this is that filter in that video so

this is three by three filter.

the second argument is what filter this

is. This is kernel size which means this

is the three by three what is filters

then?

Okay. Let's see.

So when you build a convolutional neural

network, I'm just

quickly skipping this ahead

you are

applying different filters. So let's say

one filter. Let's say you are doing

koalas image detection

one filter could be to detect eye, one

filter could be to detect nose

this way you detect

eye, nose, ear and if you have eye, nose

ear of koala you can say the image has

koala's hair too!

Similarly if you have hands and legs of

Koala you can say Koala the image has

Koala's body too!

And if you have koala's head and body it

means it can be a koala's image. So you

filled flatten that and you kind of

figure that out. So here you have one, two

three, four, five.. five layers

in our case we are going to use 32

layers. So here

how did I come with 32? Well this was

trial and error.

You need to have a lot of layers where

you can

detect

edges. you know the small features?

The second one is the actual filter size

and the beauty of convolutional neural

network is that

in this example I had to give specific

ionosphere

filter

there. Here

the neural network just figures it out

for you.

Then the activation layer the popular

activation layer for hidden layers is

always value because it's very fast to

compute

and the input shape here

256 by 256, right? So the 256 by

what is it's image size.

Okay. I'm going to maybe create a

variable using this because

that could be useful little later

and

basically I created this variable assign

it here pretty straightforward.

After convolutional layer you generally

have

pulling layer. So if you look at again

this video

you see convolutional plus value then

pulling conversion value you just keep

on repeating it

and pulling is

basically there are

different types of pulling. Here, this

image is showing you

the max pooling. Max pooling means you

have 4 by 4 pixel area you take the

maximum which is 8 eight

another four by four area what is

maximum nine. So nine

here. What is maximum-three? three three

two two

when you do this

you are preserving the features and you

are reducing the size of the image which

can be very helpful you know computation

wise. So that's exactly what we did here.

So here I'm saying I want a max pooling

layer of size 2d

and then

I before preparing this video by the way

I did some trial and error and i figured

maybe I need to stack

few max pooling and convert 2d layers.

Okay. This was trial and error you can

remove couple of layers and figure it

out. Again 30 to 60 to 64 all these

numbers are

a little bit based on that trial and

error

and then once you have stacked

the max pooling you know convert to 2d

layer max pooling layer. If you look at

this image once again

you need to now flatten it so whatever

data you get here you need to flatten it

so that it's an array of neurons and you

can have then a hidden layer here. You

know a dense layer and the final layer

is your final output classification

layer. So I'm going to

flatten it here

and then

let me add a dense layer of you know 64

neurons and then I'm going to add

okay let me say that my number of

classes is 3

and

my last layer will have three neurons

with soft max activation function.

So soft max activation function if you

don't know about it it will normalize

the probability of your classes

okay?

After that

you need to do model dot build. I mean

this is

just the API. API requires that okay

we're getting

images

must have either three or four

dimensions. Also looks like

the input shape that we gave here

is not just image it's

see what we're supplying is actually

there is channels.

And there is a batch size too.

That's the format of our input.

Okay?

Now.

Our

model architecture is ready I will just

do a quick summary we are not done

training yet by the way

so this summary just prints the quick

summary, you know. The parameters these

are the weights that you need to train

that's why it says

trainable parameter. You know you are

doing back propagation on all this

weight basically number of weights.

In deep learning we always first define

the neural network architecture so that

is this.

Then we do compile using optimizers and

all that like adam is a famous optimizer.

Then you define your loss function your

matrix

in each epoch.

what type of metric will you use to

track the

gradient descent basically? to you know..

So the accuracy is the metric that we

use to

kind of track the training

your training process.

And then finally this is the third step

which is model dot fit. Here

you actually

train your network

so in the epochs

you know we have 50 epochs.

We have batch size or batch size.

We have I will do verbose one so that it

just

prints lot of output and we can see

what's going on

and we have validation data as well. By

the way so this validation will be

used in

you know during the

each epoch it can help you track the

accuracy.

And by the way I will record all the

history of every epochs in

the history parameter so that we can do

some plot we can chart some plots later

so if this is

gonna run it's gonna take some time

based on what computer you have.

Sometimes people have

you know

gpus. So gpus makes this process faster

if you don't it might take time you can

try with less epochs in like 50s it's

taking time. 50 might be high so you can

try with less epoch but let me

explain you all these parameters that

you're seeing here. So in the first go

the loss the accuracy that you got on a

training data set was 51.

But the accuracy on validation data set

was 71 percent.

You can understand so it will train your

model first on

training data set it will measure the

accuracy and then it will kind of take

this is like running little test so it

will run little test using validation

data and it gets 71 accuracy. Okay. Then

it just keeps on running and you'll see

as we have more epochs the accuracy

keeps on improving see validation

accuracy

84 now we started with what 71.

Even the

training accuracy just keeps on

improving.

So right now I'm here at 45th epoch 46

and my

validation accuracy is already close to

one. See one it yeah it jumps up and down

but

it's pretty good actually

so now

I will run

test on my test data set. See, before you

deploy any model

you want to run a test

you want to figure out how well your

model is performing by trying it out on

a test data set. So that it's not biased.

Your model has not seen this data set.

This is the first time we are trying it

it can give us good understanding.

The accuracy comes to be 98 percent

which is

actually pretty good. And if you look at

this course parameter it's a python list

which has first parameters as loss.

The second parameter is accuracy.

Now I want to play with this history

parameter, okay?

You see history so we store history.

Let's see what this history is.

Actually,

it tells me

it's a tera's callbacks history and

immediately I'll go to my friend do you

know who is my friend? Well, Google

tensorflow

keras

callback history.

And it will give me some documentation

history has some parameters. So let me

try this parameter see what's going on

here.

Okay it's just telling me

you know that I had 50 epochs 54 steps

verbose was one and so on

it also has

history.history

So history object has another element

called history and if you look at

all the keys see you get four parameter

loss, accuracy validation loss and

validation accuracy.

Those are this parameter loss accuracy,

validation loss, validation accuracy and

we ran 50 epochs. So for each parameter

we have 50 value. See

one, two, three for loss we have 50

accuracy view 50

validation 50 and so on and that's

exactly what this is.

So if you look at

let's say accuracy let me look at

accuracy.

It's a python list 50 values so see if

you do lan

50 value correct and what are these

values? Let's check it

0.513.612

Okay

let's go here

0.513.612. So all these numbers during

epochs it will just record them in the

history and once we have those

see what we can do is this.

We can plot them in a nice matplotlib

chart you know so I will

first

get all these errors stored in different

variables and then

I will plot

the accuracy. So

let me

plot

training and validation accuracy. So this

is how you plot it.

I'm not going to go into details. This is

not matplotlib tutorial but I'm just

plotting training versus validation

accuracy and you can see that these are

epochs on the x axis.

As number of epochs so we started with

very less accuracy, one accuracy is like

perfect. So we started with point

five

you know

and it kept on jumping jumping jumping

and it went here. This graph shows that

even if you train for let's say 30 or 40

epochs is fine you don't need to go all

the way till 50 because you already

achieved

very high accuracy. And if you want to

plot another chart

next to it, let's say the

loss chart you know. Then see

the loss initially is high but it just

loss is basically an error. So an error

in back propagation keeps on reducing as

you proceed forward in your

epochs. So far it looks good. Now I want

to make a prediction so again we will go

through

test data setup. We'll run our for loop.

So we are taking just one batch. So this

will be 32 images and I will take the

first image. Okay, what is my first image?

My first image is this.

okay?

Let me just print it this is my first

image.

You see it's a tensor and if you want to

convert tensor to numpy

it's just a different format. Okay. I want

to now display this. So if you do as

type

and

you know this function it will show you

the actual image. So this is an actual

and if you print it

you see it's a three dimensional array

rgb.

Okay.

I will call it first image.

This is my first image, okay? If you do

you get second image, third image and so

on. This is my first image.

What is my first label?

My first label is

this.

Okay?

Now

I will say this

first image to predict

and then

just

that image

and

the first image

actual label

you know what?

Let me do this here.

So this is my first label

so actual label is one but I want to

know the class type. So maybe you can do

class names here and you get the

class type. So it will say okay

the actual label

is this.

This is the actual label I want to find

the predicted label, okay?

What is my predicted label?

My model is ready

I can call predict function

The predict function expects the image

batch.

Fine. I will give the image batch

and

whatever I get is the batch prediction

so this is this will be the prediction

for 32 images.

If I want the prediction for the first

image

I need to do this

badge prediction,

zero correct.

Oay so my image is potato early blight

and my prediction is this okay why is it

three dimensional array? one, two, three..

Well because of this

you see our model.

Or model architecture is

we have

three neurons and activation is soft max.

So soft max is just a probability so

there are like three probabilities

and

whatever is the highest probability that

is the class.

So you see e raised to minus 0 1 e

raised to minus 7 e raised to 18. So

this is the actual class.

Okay and if you want to

get like which is the maximum number,

there is a function called np dot arg

max.

This gives you the index.

So arc max here the answer will be

see if you have this array let me show

if you do np essentially we are doing np

dot argmax on this.

[Music]

Oh!

import

numpy

correct

the answer is zero. Meaning this the

item at the zeroth location is maximum.

Okay that will be your class? Now again

you want to convert it to class name so

you will say class names like this.

Okay you do one by one this is not

confusing by the way it's pretty

straightforward actually.

this one is a predicted labor

and you will be like okay why image is

changing well we are doing some

shuffling here. That's why image keeps on

changing.

see?

late blight late blight

only bled out so my actual label is

early blight my predicted label is also

early blight so my model is performing

awesome. see? We are trying all these

cases and it is exactly telling me what

image is this. You see this is the power

of convolutional neural network. Okay.

Nw what I'm going to do is this.

I will write a function and I'm not

going to go into detail.

I already wrote this here so this is

just a simple function

that is

taking model and image as an input and

telling you what is the predicted class

and what is the confidence. Hundred

percent confidence means say I am

the accuracy of prediction is hundred

percent, you know. So that's your

confidence score and if you look at this

we converted image into an image array

and then we created a batch out of it

after that we called predict function

and then we figured out predictor class.

This code is same as this code,

okay? So we we figured it out and we

found the confidence so we run this and

now I'm going to run my prediction

on the entire batch and I'm going to

print those

we'll run a for loop on the first batch

and

I don't want to

do prediction on all 32 images. Let me

just pick only nine images you know so I

will say for i in range nine

okay

I will first

show that particular image so you see.

But wait so it's not showing all the

images

and that's because

you need to Ithink have a subplot

then you know so see it shows all the

images.

Okay, I don't want all these axes so I

will look plt dot

access

off.

So now I don't see it. I also want to

increase the dimension so that each

image looks a little bigger. Now each

image is bigger because of this line

and

now

I want to put a title

what should be my title?

Well actual predicted label and

confidence

okay.

let's first

so I'm calling predicted function using

the model that we have and using the

image, okay.

It's giving me predicted class and

confidence and my actual class

is this. So I have predicted class actual

class and confidence and all these three

things one two three. I will print as a

plot title. So I will say plot title okay

what is my plot title?

I will use python's format string so if

you want to

display just the actual label this is

how you do it. If you use python format

string

then

you know

predicted class will be this.

So see actual class and predictor class

Okay that came now I want one more line

and I want to introduce

confidence as well.

Perfect! You see

my actual image is

early blight my prediction is only right

confidence is 100.

Confidence is pretty high in

most of see most of them is 99 this is

amazing folks. Amazing amazing

performance indeed!

Now I would like to save the model. To

save the model c we were here in this

training file right but I will create a

new directory

called models

and I will save my model here okay?

So here

I will show my model by model version so

let's say this model working is one

I can just say

model dot save

again I'm using python form string dot

dot slash models

y dot dot well

I'm in this directory if I want to go to

modules Ineed to go one step up. That's

why dot dot and then model so here then

here it will save the model okay?

again python format string

model version is one.

When I do that

here you will notice

it will see it created one.

See here it's saved model to here

and if you look at this file this is how

tensorflow models are saved. All

there are all these directories you

don't need to worry about what these are

you will be able to import model from

this one directory

and let's say one if you have one model

next time

what you might want to do is

as a data scientist you want to conduct

some experiments.

Maybe you remove data augmentation, maybe

you change model architecture a little

bit

and

you want to export let's say two or

three different versions of your model

that you can try out.

So you can

you know you can run it like you can say

okay model 2

and that will be my

second version and see it will save it

here right now they are same but maybe

you can make some changes here.

You know in your model architecture

or maybe change optimizer

and save different versions.

If you want to keep a running count

and kind of figure out.

Okay, if there is a two directory then

automatically increment the model

version

then you can do that using OS

library. See if you have import OS

and if I do OS dot list directories

if I do this what's gonna happen.

See? It is telling me

what directives we have

now.

This is returning me string how do you

convert string to an integer?

Well it's very simple. You use list

comprehension

you will say

okay

end i.

For i in this

and you get integer

if you want to

listen model zero

as version you can get that also

and

eventually we find a max of all this

and max of this is two and when you do

one you get your next model version. So

this is how you get your

next model version. So I'm just going to

say this is my model version

okay?

And

I want to save it like this

so now when I save this and when I run

it created version 3. if I run it again

it automatically creates version four

version four and so on.

So this way you can auto increment your

models.

So folks, that's all I had for this video.

In the next video we are going to build

a fast API

server

and also we will be using tensorflow

serving actually to

load all these models. So we'll cover all

of that but as an exercise

I want you to change this model for

tomato classification

so we tried potatoes, okay?

You need to do this exercise where you

are building this

model for this tomato classification and

there are many classes so it will

require some changes into your model

architecture. But that's an exercise a

sincere student is the one who works on

the exercise.

If you

work on exercise you will learn a lot of

useful things. All right, if you like this

video please give it a thumbs up and

share it with your friends so that they

can also benefit and I will see you in

the next video in the same tutorial

series. Thank you very much.

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YouTube Transcript:Deep learning project end to end | Potato Disease Classification - 3 : Model Building

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YouTube Transcript:
Deep learning project end to end | Potato Disease Classification - 3 : Model Building