I have a folder with hundres/thousands of images, some of them look alike. I would like to create clusters separating those images (those which look alike in the same cluster).
I can't determine the number of clusters that will be needed, it depends on the images.
Does anyone have an idea on how to do this using Python, OpenCV and which algorithm to use?
I've made some research and found that AffinityPropagation or DBSCAN can be useful for me but I don't know where to start (how to encode my images, what should I pass to those algorithms etc...)
Unfortunately it is not that simple with images, since naively clustering would result in clusters of images with the same colors, not the same "content". You can use a neural network as a feature extractor for the images, I see two options:
Use a pre-trained network and get the features from an intermediate layer
Train an autoencoder on your dataset, and use the latent features
Option 1 is cheaper since you can easily find pre-trained models, option 2 is much more computationally expensive but should work better, especially if there is no pre-trained model on your domain.
This tutorial (randomly found on the internet) seems to be a good introduction to method 2.
Related
As an example I have two pictures with a particular type of clothing of a certain brand.
I can download a lot of different images of this same piece, and color, of clothing
I want to create a model which can recognize the item based on a picture.
I tried to do it using this example:
https://www.tensorflow.org/tutorials/keras/classification.
This can recognize the type of clothing (eg shirt or shoe or trousers, etc) But not a specific item and color.
My goal is to have a model that can tell me that the person on my first picture is wearing the item of my second picture.
As mentioned I can upload a few variations of this same item to train my model, if that would be the best approach.
I also tried to use https://pillow.readthedocs.io
This can do something with color recognition but does not solve my initial goal.
i don't think that CNN can help you in your problemes, take a look at the SIFT Technique see this for more détails.it is used for image matching and i think it's better in your cas. if your not looking to get in to much detailes the opencv is a python (and c++ i think) library that has image matching function that are easy to use more détails .
As mentionned by #nadji mansouri, I would use SIFT technique as it suits your need. But I want just to correct something, CNN is also a thing in this case. This being said, I wouldn't tackle the problem as a classification problem, but rather using Distance Metric Learning, i.e, training a model to generate embeddings that are similar in the space when the inputs are similar, and distant otherwise. But to do this you need a large representative dataset.
In short, I suggest starting with SIFT, using OpenCV, or open source implementations on GitHub, playing around with the parameters and see what fits your case best, and then see if it's really necessary to switch to a neural network, and in this case tackling the problem as a metric learning task, maybe with something like siamese networks.
Some definitions:
Metric learning is an approach based directly on a distance metric that aims to establish similarity or dissimilarity between data (images in your case). Deep Metric Learning on the other hand uses Neural Networks to automatically learn discriminative features from the data and then compute the metric. source.
The Scale-Invariant Feature Transform (SIFT) is a method used in computer vision to detect and describe local features in images. The algorithm is invariant to image scale and rotation, and robust to changes in illumination and affine distortion. SIFT features are represented by local image gradients, which are calculated at various scales and orientations, and are used to identify keypoints in an image. These keypoints and their associated descriptor vectors can then be used for tasks such as image matching, object recognition, and structure from motion. source, with modification.
I have a database of images that contains identity cards, bills and passports.
I want to classify these images into different groups (i.e identity cards, bills and passports).
As I read about that, one of the ways to do this task is clustering (since it is going to be unsupervised).
The idea for me is like this: the clustering will be based on the similarity between images (i.e images that have similar features will be grouped together).
I know also that this process can be done by using k-means.
So the problem for me is about features and using images with K-means.
If anyone has done this before, or has a clue about it, please would you recommend some links to start with or suggest any features that can be helpful.
Most simple way to get good results will be to break down the problem into two parts :
Getting the features from the images: Using the raw pixels as features will give you poor results. Pass the images through a pre trained CNN(you can get several of those online). Then use the last CNN layer(just before the fully connected) as the image features.
Clustering of features : Having got the rich features for each image, you can do clustering on these(like K-means).
I would recommend implementing(using already implemented) 1, 2 in Keras and Sklearn respectively.
Label a few examples, and use classification.
Clustering is as likely to give you the clusters "images with a blueish tint", "grayscale scans" and "warm color temperature". That is a quote reasonable way to cluster such images.
Furthermore, k-means is very sensitive to outliers. And you probably have some in there.
Since you want your clusters correspond to certain human concepts, classification is what you need to use.
I have implemented Unsupervised Clustering based on Image Similarity using Agglomerative Hierarchical Clustering.
My use case had images of People, so I had extracted the Face Embedding (aka Feature) Vector from each image. I have used dlib for face embedding and so each feature vector was 128d.
In general, the feature vector of each image can be extracted. A pre-trained VGG or CNN network, with its final classification layer removed; can be used for feature extraction.
A dictionary with KEY as the IMAGE_FILENAME and VALUE as the FEATURE_VECTOR can be created for all the images in the folder. This will make the co-relation between the filename and it’s feature vector easier.
Then create a single feature vector say X, which comprises of individual feature vectors of each image in the folder/group which needs to be clustered.
In my use case, X had the dimension as : NUMBER OF IMAGE IN THE FOLDER, 128 (i.e SIZE OF EACH FEATURE VECTOR). For instance, Shape of X : 50,128
This feature vector can then be used to fit an Agglomerative Hierarchical Cluster. One needs to fine tune the distance threshold parameter empirically.
Finally, we can write a code to identify which IMAGE_FILENAME belongs to which cluster.
In my case, there were about 50 images per folder so this was a manageable solution. This approach was able to group image of a single person into a single clusters. For example, 15 images of PERSON1 belongs to CLUSTER 0, 10 images of PERSON2 belongs to CLUSTER 2 and so on…
I am very new to machine learning and have been implementing ML algorithms on the datasets.
But how do I go about classifying images using the Ml algorithms?
How do I feed the images to the learning models in the form of numpy arrays?
Can anyone brief me about the steps involved? I have been reading about feature extraction but I am not able to figure out how to do that.
Image classification is not much different, at its core, from any other sort of classification.
Your data are images, right? Well, we need to create some variables ("features") from those images in order to get a sense of what's in the images. Computers can understand matrices, not just straight-up images like humans do (although there are arguments that what humans are doing when they see images is deconstructing images into patterns of pixels, but let's keep it simple). Using OpenCV is a great way to turn image pixels into matrices.
Each matrix (i.e. each image) will have a corresponding tag or classification (e.g. "dog" or "cat"). You feed those matrices through your algorithm in order to classify each image.
That will get you started. There's so much that goes into machine learning related to images, but at its core, the problem is the same as elsewhere: take a matrix/set of data and use an algorithm to find patterns in the data and a function that maps the input to the output label. You might be served well by reading an intro to machine learning book or taking a course.
I'm in need of an artificial neural network library (preferably in python) for one (simple) task. I want to train it so that it can tell wether a thing is in an image. I would train it by feeding it lots of pictures and telling it wether it contains the thing I'm looking for or not:
These images contain this thing, return True (or probability of it containing the thing)
These images do not contain this thing, return False (or probability of it containing the thing)
Does such a library already exist? I'm fairly new to ANNs and image recognition; although I understand how they both work in principle I find it quite hard to find an adequate library for this task, and even research in this field has proven to be kind of a frustration - any advice towards the right direction is greatly appreciated.
There are several good Neural Network approaches in Python, including TensorFlow, Caffe, Lasagne, and sknn (Sci-kit Neural Network). sknn provides an easy, out of the box solution, although in my opinion it is more difficult to customize and can be slow on large datasets.
One thing to consider is whether you want to use a CNN (Convolutional Neural Network) or a standard ANN. With an ANN you will mostly likely have to "unroll" your images into a vector whereas with a CNN, it expects the image to be a cube (if in color, a square otherwise).
Here is a good resource on CNNs in Python.
However, since you aren't really doing a multiclass image classification (for which CNNs are the current gold standard) and doing more of a single object recognition, you may consider a transformed image approach, such as one using the Histogram of Oriented Gradients (HOG).
In any case, the accuracy of a Neural Network approach, especially when using CNNs, is highly dependent on successful hyperparamter tuning. Unfortunately, there isn't yet any kind of general theory on what hyperparameter values (number and size of layers, learning rate, update rule, dropout percentage, batch size, etc.) are optimal in a given situation. So be prepared to have a nice Training, Validation, and Test set setup in order to fit a robust model.
I am unaware of any library which can do this for you. I use a lot of Caffe and can give you a solution till you find a single library which can do it for you.
I hope you know about ImageNet and that Caffe has a trained model based on ImageNet.
Here is the idea:
Define what the object is. Say object = "laptop".
Use Caffe's ImageNet trained model, change the code to display the required output you want (you mentioned TRUE or FALSE) when the object is in the output labels.
Here is a link to the ImageNet tutorial which I wrote.
Here is what you might try:
Take a look here. It is a stripped down version of the ImageNet program which I used in a prediction engine.
In line 80 you'll get the top-1 predicted output label. In line 86 you'll get the top-5 predicted labels. Write a line of code to check whether object is in the output_label and return TRUE or FALSE according to it.
I understand that you are looking for a specific library, I will look for it, but this is something I would try out in the beginning.
I am currently analyzing a set of pictures, that I want to classify.
Classification is done by a Artificial Neural Network in a supervised manner.
I have a test set that assigns to a each picture its class.
What I want to do now is generate a lot of descriptors and then do a PCA on these
and do a statistical analysis how much the descriptor is able to describe the
class of the picture.
How can i generate descriptors for these pictures programatically? This could help me in future classification problems too. Let us assume I have enough computation power (100 core cluster)
Are there libraries that incorporate a lot of descriptors for images?
You can basically follow two approaches to start:
Feature based, using methods such as SIFT or GIST followed by the so called Bag of Words approach. The vlfeat site contains an excellent demo of this.
Deploying deeplearning algorithms, such as the Sparse Autoencoder to learn basic features of your dataset which can then be further used for classification.