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Table of content
- Related works
- Experiment Setup and Implementation
- Results and Analysis
Human face recognition and feature extraction have been the most interesting technologies to study for many researchers. It allows a huge number of face images to be recognized in just a short amount of time and extract the face features very easily, rather than recognizing each image and it’s features individually through a normal human’s eyes.Using these technologies researches are being carried out to find the look-alike characters within humans. Using methods for real people, cartoon character faces can hardly be detected and recognized because the face features of cartoon characters differ greatly from those of real people in terms of size and shape. This research was conduct to find the techniques to face detection,feature extraction of a cartoon characters and recognize look-alike cartoon character for a given human image. We have created Disney cartoon repository including 800 images from 77 characters, 5 images from each character with mirror images. Also include face features marked by hand as 35 labeled coordinates. For cartoon face detection and feature extraction, landmark based model trained using feature marked dataset. Used distances and the areas between the landmarks as features. Total 92 features(50 areas and 42 distances) are stored as csv files along with the cartoon images. To compare features of a real image with all the cartoon image features euclidean distance was considered. To increase the accuracy we used landmark based model with hair extraction model and also include gender prediction model. This combined model improves the performance compared to basic landmark based model. Alternatively, we implemented a classification model to find the best matching cartoon character. It shows 84\% accuracy on training data and 80\% accuracy on validation after 100 epochs. Finally we were able to find the best matching Doppelganger Cartoon character with good accuracy. So we hope this research and the dataset created by us will be more useful to other researchers.
There is not any directly related project happening to find a machine learning algorithm that can find the cartoon character that best looks like you. But some websites published manually founded cartoon images with their matching human image . Also, some websites provide the best matching celebrity image for your uploaded image.Chase, Davis, and Amanda Jacquez did the research and reported it called Finding Your Celebrity Look Alike. They found vector representation of faces and then used OpenCV HaarCascade classifier in order to detect faces. Images inputted to the system and images in IMDB-WIKI data set were represented as 2622 dimensional vectors. Then IMDB-WIKI data set to compare with the inputted image and find the similarities between them. According to that, they find the best matching celebrity image/images using the Euclidean distance.
A similarity measure is defined as the distance between various data points. Measuring the similarity between two images is mostly used in image retrieval and computer vision Fields. SimNet is a methodology proposed by Srikar Appalaraju and Vineet Chaoji, This deep siamese network is trained on pairs of positive and negative images using a novel online pair mining strategy inspired by Curriculum learning. Wang, J., Song, Y., Leung, T., Rosenberg, C., Wang, J., Philbin, J., Chen, B. and Wu, Y. proposed a deep ranking model that learns the similarity metrics directly from images. By comparing the models which are based on handcrafted features, this approach has higher learning capability. Their goal was to learn similarity models. Euclidean distance and nearest neighbor search problem concepts were used to rank similar images. For ranking the loss function, a triplet based network was proposed and image triplets were taken as the inputs. Because of the recent success of the ConvNet for image classification, they started a convolution network that contains convolution layers, max-pooling layers, local normalization layers, and fully-connected layers for each individual network. An asynchronized stochastic gradient algorithm with a momentum algorithm was used because training a deep neural network needs a large amount of data. The ImageNet ILSVRC-2012 data set was used as training data which contains roughly 1000 images in each of 1000 categories. A relevance training data which was generated in a bootstrap fashion was also used as a training data set.
Face Detection & Recognition
The computer technology that finds and identifies the human faces in digital images is called face detection. Feature -based approach and image-based approach are the two main approaches of detecting faces of real people. Imager:: Anime Face is an image-based approach which is used to detect faces of cartoon images. This method finds that the input images are faces or non-faces. As face detection, face recognition also can be classified into two categories called model-based approach and image-based approach. Kohei Takayama, Henry Johan and Tomoyuki Nishita proposed the first relevant work concerning face detection and face recognition of cartoon characters extracting the features. In face detection the skin and the edges of the input image were extracted firstly. Edges were extracted using Canny Method and they considered that the skin color of the cartoon image has to be near to real people. Jaw contour and Face symmetry are used to face detection. For comparison, OpenCV Face Detection and Imager:: AnimeFace are used as candidates and 493 various cartoon characters are given as inputs. By comparing the results, the proposed method is more accurate than the previous method. Feature extraction of the detected face and determination of the individuality of the face and Character search are the main two purposes of their face recognition system. Skin color, Hair color and the Hair quantity are the three features that they extracted to build the feature vector. Face similarity is calculated by measuring the distance between the features of two feature vectors of input image and images in the database. 71% of output images contain the same characters as input images(success) and 29% of the search are failure. Saurav Jha, Nikhil Agarwal and Suneeta Agrawal presented a methodology to improve the Cartoon Face Detection and Recognition systems. MTCNN architecture which offers a deep cascaded multi-task framework is used to face detection. This architecture has three sequential deep CNNs and they are Proposal Net, Residual Net and the Output Net. For securing the baseline results, Haar Features and HOGfeature are employed. Face recognition is experimented on two different techniques, inductive transfer using inception v3 + SVM/GB and their proposed method. The proposed method has two phases. The first phase consists of preprocessing ( converting the cartoon image to gray scale and normalized), landmark extraction(15 facial landmarks of 750 images of 50 characters) and landmark detection(5 layer LetNet architecture). In phase 2, leverages the images using a hybrid CNN (HCNN) model. Benchmark IIIT-CFW database which contains 8,928 annotated cartoon images, is used as the dataset.
Feature extraction is important when finding a similar face to another face such as face recognition, face detection, and expression detection. Eyes, mouth, and nose are the most important features for face recognition. Hua Gu, Guangda Su, and Cheng Du from Tsinghua University proposed a method to extract feature points from faces. This approach is based on human visual characteristics. The features of the face are extracted with the properties by using the geometry and the symmetry of faces. Normalizing the image size before processing is not needed in this method. Integrating the local edge information is not easy when we extract the face features. In this method, the Smallest Univalue Segment Assimilating Nucleus(SUSAN) operator was chosen to extract the edge and corner points of the feature area. Feature points were located by using face similarity and geometry. Lilipta Kumar Bhatta and Debaraj Rana proposed a technique for extracting facial features from a color image through skin region extraction. Extracting the characteristics of human face color and face region using Sobel operator, Converting the image into YCbCr components and extracting skin region using morphological operation, and extracting the regions of the human eye, mouth, and nose by means of gray level intensity value were the three steps of their proposed technique. FEI face database was used for their experiment. They normalized the image size to 640*480. Using this technique, they experimented and showed that the locating of the feature points is exact and fast, this technique increases the accuracy of face recognition.
Face Landmark Detection
Facial landmarks detection is used in many computer vision applications like face alignment, drowsiness detection, face recognition, facial expression analysis, facial animation, 3D face reconstruction as well as facial beautification, etc. The aim of face landmark detection is to detect the predefined key points like eyes, eyebrows, mouth, nose, etc. Yue Wu·Qiang Ji classified these detection algorithms into three methods like holistic methods, Constrained Local Model (CLM) methods, and regression-based methods depending on how they model the facial appearance and facial shape patterns. The holistic methods models represent the global facial appearance and shape information. The Constrained Local Model leverages the global shape model but builds the local appearance models. And the regression-based methods capture facial shape and appearance information.  Yongzhe Yan1,Xavier Naturel,Thierry Chateau, Stefan Duffner, Christophe Garcia, Christophe Blanc divided facial landmark detection algorithms mainly into two types, generative or discriminative. The generative types algorithms, which include the partbased generative models like ASM and holistic generative models like AAM, model the facial shape and facial appearance as probabilistic distributions. They have provided a comparison of different face alignment methods as well as different deep compression models. To this comparison, they included traditional cascaded regression methods and deep learning-based face alignment methods. Zixuan Xu1, Banghuai Li2, Miao Geng3, Ye Yuan identified that face landmarks detection becomes a challenging task when dealing with faces in unconstrained scenarios, especially with large pose variations. They targeted the problem of facial landmark localization across large poses and give a solution based on a split-and-aggregate strategy. When splitting the search space, they proposed a set of anchor templates as references for regression, which well solved the problem which had with large variations of face poses. Then depending on the prediction of each anchor template, they proposed to aggregate the results, which reduce the landmark uncertainty due to the large poses.
Since the appearance of hair can vary between different people based on their gender, age, ethnicity, and the surrounding environment, automatic hair segmentation is challenging in general. Recently, there has been much success with deep neural networks (DNNs) and in many tasks, including semantic segmentation, DNN-based hair segmentation methods havebeen introduced. The work of Liuet al.  introduced a multi-objective learning method for deep convolutional networks that jointly models pixel-wise likelihoods and label dependencies. A nonparametric prior was used for additional regularization, resulting in better performance. Guo and Aarabi  presented a method for binary classification using neural networks that perform training and classification on the same data using the help of a pre-training heuristic classifier. They used a heuristic method to mine positive and negative hair patches from each image with high confidence and trained a separate DNN for each image, which was then used to classify the remaining pixels.
A machine learning algorithm to find the doppelganger cartoon for a given image is the final outcome of this research. After reviewing previous works on face detection, feature extraction and feature comparison, the proposed methodology is under the following conditions. • Cartoon images are limited to only Disney characters. • Full body of cartoon images and real human images are not compared. • Real human images should be given as the input.
There are more approaches done to detect faces, extract features and measure similarity of images of real images and cartoon images separately. But there are very few applications that compare cartoons and real humans using these concepts. After an extensive study of the work done by various approaches and experiments, we came up with a methodology. This application provides a number of analysis steps including preprocessing, face detection, feature extraction, measuring similarity and displaying the results with a user friendly web application. The web application is designed for users who want to find the doppelganger of him/her. The real image is obtained and the result is displayed through the web application. Image preprocessing, face detection, feature extraction and measuring similarity steps are done in the backend.
For image classification tasks there are some popular data sets that are used across research and industry applications. The most popular ones are Imagenet, CIFAR, MINST. But for tasks like cartoon-human image similarity checking there is no well-known dataset that can directly be used. There are some freely accessible comic and animated cartoon image repositories which differ more from human faces out there. Cartoon image repository in this research is only contained with Disney cartoon images which are more similar to human faces to simpler this approach as this is the beginning. Disney cartoon repository, created by our own and ibug 300-w Human repositories are used to train the landmarks detection model. For the classification model, the dataset contains 58 Disney cartoon characters with 406 images, 348 images for training, and 58 images for validation. To test each algorithm of predicting the doppelganger cartoon image, we used a test set contains 20 already known doppelgangers.
Normalizing the images before feeding them into models is caused to give good results and specific sizes are required from most models. Image data normalization ensures that each pixel has a similar data distribution. This causes us to speed up the converging process. Data normalization can be done by subtracting the mean from each pixel value and dividing them by the standard deviation. So the normalized data is in the range of [0,1] or [0,255]. As we were only considering 35 special landmarks on the face, we extracted that 35 landmarks from the given 68 landmarks in the human dataset ibug 300-W dataset. The special 35 landmarks, considered in this research, is shown in the Figure 3.4.
Face detection and Feature extraction
After preprocessing images the next step is to extract features. This is the most important part of this project because the accuracy of the algorithm directly depends on the extracted features. Face detection and feature extraction can be done by various approaches. These approaches are discussed in the section Face detection and Feature extraction
Store extracted features
When comparing images going through all the images in the repository, extracting features and checking similarities will take a lot of time and need considerably huge performance. So to reduce the effect of above problems we stored the extracted features of cartoon images in a csv file with the image paths. So it is easy to go through the csv file and check similarities with features extracted from human images.
Distance metric or matching criteria is the main tool for finding the similar images. Two vectors, a vector with extracted features of the real human image and a feature vector of a cartoon should be compared to find the similarity of the two images. The L1 metric (Manhattan Distance), the L2 metric (Euclidean Distance) which are main two distance metrics, have been proposed in the literature for measuring similarity between feature vectors. Euclidean Distance : If there is two points a and b have n dimensions such as a=(x1 ,x2,…,xn) and b=(y1,y2,…,yn) , the Euclidean distance between two points can be generalized as in Equation 3.1
The calculated Euclidean distances of each cartoon feature vector with the real image feature vector are compared and the cartoon image with the least distance is selected as the best matching cartoon image for the real image.
Experiment Setup and Implementation
Data manipulation and Testing
Our cartoon data sets is a repository containing Disney cartoon images. Though the pretrained models are not perfectly detecting the cartoon faces, this dataset is containing only frontal faces of cartoon images. Data manipulation for cartoon landmarks detection model is done by annotating the landmarks on the cartoon faces using a tool. The iBUG 300-W dataset which has already annotated landmarks is used as the human dataset to train the model for landmarks detection.
Pitfalls and workarounds
During this project, one of the main challenges encountered was to get the background knowledge of the data set, feature extraction and face detection of images. As a remedy for that issue, we had to do lots of background research. Finding a strong data set with cartoon images is required for our task. At first, we could not properly understand the already existing data sets. After gaining knowledge about previous works, we understood that there are a number of data sets which contain various cartoon images but existing data sets are still lacking similarities compared to humans. As a solution, we decided to collect images to build a Disney cartoon image repository on our own as Disney cartoons
are more similar to human images. But still the lack of data for training purposes has remained. A number of researches are done on face detection and feature extraction. But one issue with that was lack of documentation about feature extraction and face detection of cartoon images. After reviewing the research papers, we had to spend a considerable amount of time figuring out how the pretrained models work on cartoon images and human images to select a best model for our case. By analyzing the results given by the models, we figured out that the pretrained models are not performed well in cartoon face detection. But actually training a model from scratch is very expensive and requires huge data sets to achieve good generalization performance. The method landmarks detection, is required to detect the face first and detecting face of cartoon images is not similar to human face detection. We handled this by using the frontal face of cartoons and using the dlib frontal face detector as the detector. Also, when running the code on google colabs, due to the high throughput of the data set, we faced an issue of insufficient memory and low speed. We handled this problem by switching the run time mode to GPU from none in the Google Colabs environment.
Results and Analysis
All the algorithms we tried on this research are tested on the same test set which contains already known doppelgangers. To compare the models we ranked the resulted images according to the ascending order of euclidean distance. Table 5.2 Shows the summary of ranks for each cartoon. For some images, the models do not give an output because of some failures in the hair extraction model or gender prediction model for some cases. As an example, some female images can have short hair, then the gender prediction model wrongly predicted the gender and then our expected result is not within the resulted images. Figure 5.32 shows the variation of the ranks of each cartoon character for different weight values. By analyzing the graph, we can conclude that the rank varies for different weights. Some cartoons get better rank in w = 0.5 and someones get better at w=0.2. The graph of w=1 (landmarks-based model only) always gives higher ranks (far away from expected result) for all cartoons with respect to other models. According to the graph, w=0.2 and w=0.5 (combined model) gives some good ranks for all cartoons. But according to the classification results in the Table 5.2, the classification model gives the best results for all cartoons as all the expected outputs are within the top 5 ranks.
During recent years, many researches have been carried out in various ways of feature extraction of human images, finding looks-alike twins, and so on. We entered the research using the pre-trained model based approach and after analyzing the results, we concluded that we should simplify this by considering only the Disney cartoons which are more similar to humans as this is the beginning and train our models for building the algorithm. In this paper, we mainly researched an approach that finds the best matching Cartoon character for human image based on landmarks model. Because lack of existing cartoon datasets, we have created a dataset with landmarks on the faces of cartoon characters for training a model and it will be more useful for future researchers. Combination of landmark based model with hair extraction model and gender prediction model has improved the performance. But the best cartoon image is resulted for different weights on the models for various images. Alternatively implemented classification model shows 84% accuracy on training data and 80% accuracy on validation after 100 epochs. As features on cartoon faces such as eyes, nose are more differ from human features, the combined model is also not accurate like classification. So, the classification algorithm with a strong dataset will be the best model for this finding doppelganger task. Today’s society is interesting to compare their appearance with cartoons because it brings mental relaxation and fun for their minds. So we hope this research will be helpful for them.