Questions tagged [yolo]

"You Only Look Once", a Deep Learning-based object recognition algorithm available in several different software implementations.

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Why use multiple anchor boxes with the same positions in a multi-box detector?

What is the benefit of using multiple anchor boxes with the same positions in a single-shot multi-box detector model, like YOLO? In particular, I notice Google's BlazeFace model does this. If the ...
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Why Anchor Boxes in Object Detection

What I understand from the anchor boxes is that they are predefined set of boxes of different sizes and shapes. A model like YOLO predicts offsets of the coordinates for each anchor box along with ...
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1 neuron BCE loss VS 2 neurons CE loss

I built a custom version of YOLO that should only detect one type of objects, where the objectness measure (which tells how likely a bounding-box contains an object of any type), is learned using a ...
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yolo v1: how gradients in grids with no objects overpower

I am reading yolo v1 paper. I am having confusion while trying to understand this: "Also, in every image many grid cells do not contain any object. This pushes the “confidence” scores of those ...
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44 views

yolo v1: why we weigh localization error more than classification error

I'm reading yolo v1 paper. I am trying to understand this part of the paper: "We use sum-squared error because it is easy to optimize, however it does not perfectly align with our goal of ...
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Yolo for object detection

I am working on (RSNA Pneumonia Detection Challenge) of kaggle. In which we have to find if a patient is suffering from pneumonia and if suffering then find the abnormality in the image by finding ...
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27 views

In the case of YOLO, how does the network assign a box in it's grid based on the midpoint of the object?

My question is that how in YOLO, the networks does the midpoint of grid cell think ? I'm not completely sure I understand it. How can we know the midpoint of any object before actually knowing where ...
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22 views

When training a Neural network, how important it is to finish a training such that the epoch is an integer?

When training an object detection model, I am wondering how important it is to choose the number of iterations such that the training completes "full" epoch? Here is an example that, I hope, will make ...
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Best way for robust hand tracking on PI 4

I need a robust hand tracking which should be running on a Raspberry Pi 4 model. Does anyone have some experience with that? One way could be to use OpenCV but I think it's just using the skin color ...
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367 views

Yolov3: Single-class vs multiple class

I'm really new to object detection with Yolov3. Let's say I have 10 classes and the amount of data is approximately the same. Do I achieve better average precision when I use 10 Yolo models and train ...
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Retraining of object detection CNN

I am working on an object detection system that should detect UI elements (such as button, checkbox, radio button, etc..) in the photo of a touch screen of printer (not screenshots, but literally a ...
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1answer
32 views

Performance of MaskRCNN/YOLO as a function of object size in pixels

I am trying to find references on how the resolution of an object affects the ability of object detection systems such as MaskRCNN and YOLO to correctly identify the object. For example, if the ...
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What is the purpose of grids in YOLO?

Considering the YOLO algorithm. Assume: Input image is n x n x 3 Number of anchor boxes is m For each anchor box, we have 1 (pc = probability of object) + 4 (4 variables to predict the bounding ...
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1answer
88 views

How exactly the midpoint of the object is selected in YOLO algorithm?

The boundaries of the object are encoded into 4 scalars: Bx, By, Bh, Bw. Bh and Bw are calculated using the ratio of the width of the bounding box to the width of the relative grid cell. But I can't ...
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346 views

Change hyperparameter of YOLOv3 for face detection

I have tried with some github implementation on YOLOv3 in tensorflow. I trained yolov3 for faces with WIDER face dataset, I haven't changed the original configuration of YOLOv3. After training the ...
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How are YOLO anchor boxes generated?

I am recently trying out darkflow, a Tensorflow implementation of Darknet written by Joseph Redmon. Looking at the configuration files, I noticed a section called region as shown below. ...
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290 views

The reason for multiple bounding boxes use for each grid cell - YOLO

I'm not quite sure what is the main reason why YOLO uses multiple bounding boxes for a grid cell. An answer I can find on web is for multiple aspect ratio in the prediction. However I don’t think it’s ...
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What is sigma function in the YOLO object detector?

I have gone through the YOLO9000 paper, in that they have mentioned that network predicts 5 coordinates of the bounding box, and from that we find the exact centre coordinates and the width and height....
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222 views

Combining custom YOLO network for face detection with another CNN

I am looking for a way to build and train an end-to-end CNN that contains two steps: 1) a CNN for finding a face and hands in the image and 2) CNN that works on the crops of the face and hands. To ...
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135 views

How to “use” Yolo Loss Function

I am dealing with Yolo Loss Function (the following). $$\begin{align} &\lambda_{coord} \sum_{i=0}^{S^2}\sum_{j=0}^B \mathbb{1}_{ij}^{obj}[(x_i-\hat{x}_i)^2 + (y_i-\hat{y}_i)^2 ] \\&+ \lambda_{...
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1answer
3k views

YOLOv3 loss function

Follow-up to stats.stackexchange.com/questions/373266/yolo-v3-loss-function: In trying to finalize the development of my training labels and loss function I'm confused by the part in bold in the ...
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958 views

what purpose do the grid cells serve in YOLO object detection algorithm?

so I was looking at YOLO and I read several blogs online, but one concept I'm having trouble understanding is why do we want to divide the image into different grids, and then predict the bounding box ...
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Is YOLO a good algorithm for defect detection on images?

I wish to train an algorithm to detect defects on images of labels. These may be such things as scratches, tears and voids. I would like to try to train a YOLO algorithm to do this, but it is very ...
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Yolo v3 loss function

The original loss function can be seen here and is more or less explained in Yolo Loss function explanation: \begin{align} &\lambda_{coord} \sum_{i=0}^{S^2}\sum_{j=0}^B \mathbb{1}_{ij}^{obj}[(x_i-...
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1answer
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On Yolo, and its loss function

I'm having a hard time understanding some on the inner-working of YOLO, especially the loss function depicted in this seminal paper. Bear in mind that I'm nowhere closed to being a specialist in deep ...
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801 views

What is the need of multiple Bounding Boxes per grid cell in YOLO v1?

This question is regarding YOLO v1 architecture as in here. I am confused as to why authors have used 2 bounding boxes per grid cell for training. Assuming there can be only one object per grid cell. ...
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1answer
809 views

Understanding the YOLO algorithm

I am trying to understand the logic behind object detection and the YOLO algorithm. I have read numerous blogs, tutorials, videos, papers, yet I am still not sure if I understood it correctly. Let's ...
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1answer
1k views

YOLO loss function width and height component explanation

I am reading this paper on how yolo defines loss function. https://arxiv.org/abs/1506.02640 I did research on other posts, but these posts did not seem to answer my confusion: (How to calculate the ...
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1answer
845 views

yolo cost function

At the output of the final layer of yolo, a leaky-relu is applied to the output, so if we have negative values for the width and height, the cost function will return a null value since we would have ...
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1answer
2k views

object detection loss function YOLO

as we know , in detection we have 2 loss : one is localization loss other is classification loss , in the formulation the 1th , 2th term related to localization loss and 3th term is related to ...
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1answer
799 views

Yolo loss function for detecting 1 class

I'm trying to work on a Yolo implementation which searches a 19x19 grid to find a specific item. There is only a single class in all of these images I am looking to get bounding boxes for. I'm a ...
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2answers
2k views

How does the YOLO network create boundaries for object detection?

I'm not sure I understood how the YOLO network works. If you look at the description, https://pjreddie.com/darknet/yolo/, it appears to me that all is done thanks to convolution only. You end up with ...
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2answers
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Adjusting Grid Size in YOLO?

I was going through the YOLO Object Detection Paper by Joseph Redmon. The authors use a grid size of $S = 7$. If I am not wrong, the network architecture has carefully been curated for this specific ...
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3answers
2k views

You Only Look Once (YOLO): Convolutional Neural Network

This question refers to the YOLO architecture (figure 3). In their architecture they define a convolutional layer 7x7x64-s-2 followed by a maxpool layer ...
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5answers
32k views

Yolo Loss function explanation

I am trying to understand the Yolo v2 loss function: \begin{align} &\lambda_{coord} \sum_{i=0}^{S^2}\sum_{j=0}^B \mathbb{1}_{ij}^{obj}[(x_i-\hat{x}_i)^2 + (y_i-\hat{y}_i)^2 ] \\&+ \lambda_{...
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1answer
2k views

How to calculate the class probability of a grid cell in YOLO object detection algorithm?

I am going through the YOLO paper by Redmon, Divvala, Girshick & Farhadi (2015), "You Only Look Once: Unified, Real-Time Object Detection" (arXiV page here ) On the fourth page it mentions the ...