Questions tagged [image]

This tag covers signal processing where input is an image, such as a photograph or video frame and the output could be an improved or altered image, parameters related to the image or information about features within the image.

Filter by
Sorted by
Tagged with
10
votes
5answers
1k views

Auto Detection of Rotation Angle on Arbitrary Image with Orthogonal Features

I have a task at hand where I need to detect angle of an image like the following sample (part of microchip photograph). The image does contain orthogonal features, but they could have different size, ...
0
votes
1answer
1k views

Recovering an image using IDCT through DCT coefficients

I have computed the discrete cosine transform (DCT) of an image in MATLAB. I got a matrix of discrete cosine transform coefficients in the workspace. How can I recover the original image from its ...
1
vote
2answers
107 views

Image downsampling with Haar DWT?

How can the resolution of an image in matlab be reduced by using 2D haar wavelet by downsampling-decimation? Is there any predefined code or tool within wavemenu? thanks in advance
0
votes
2answers
42 views

Camera image pixel structure origin

I am using machine vision for industry task with opencv. I have images from a camera monitoring the process. The detailed look at the small part of the image follows: Enlarged: In the detail, it ...
9
votes
1answer
864 views

Removing Noise from Dental Radiography

I'm working on a project of applying Active Shape Model to locate tooth in dental radiograph. For those familiar with the technique, I'm currently trying to sample along normal vectors for each ...
3
votes
5answers
26k views

Noise Removal from an Image Using OpenCV (Comparison to Neat Image)

I tried removing noise from the image shown below using Median Blur in OpenCV. But i'm not able to remove the colour noise completely as it is done in Neat Image. Any suggestions.? 1. Original Input ...
2
votes
1answer
177 views

How to Calculate the Hann Low Pass Filter / Kernel for Image Processing

I'm currently studying for an exam in image processing and stumbled upon a exercise which i could not answer and my professor will not be available before the exam anymore. The exercise goes as ...
4
votes
1answer
788 views

Formula for 2D Image Filter for Scratch Detection

Consider Multidirectional Scratch Detection and Restoration in Digitized Old Images Research Paper. In section 4.1 (Preprocessing), they gave us a formula of the kernel, $$ H(u, v) = \frac{1}{1+0....
1
vote
1answer
2k views

Convolution in Image Processing?

I got the concept of Convolution in signal processing from a video lecture that it is method to get the area overlapped between two signals when one signal is flipped over and traversed over another ...
1
vote
1answer
139 views

Detection Algorithm in 2D Images

Suppose there is a two-deimensional image which consists of pixels. In every pixel, there are 0 to n apples with different colors, which can be digitalized(e.g.[0,10000]). So we can plot a histogram ...
2
votes
2answers
657 views

Is there a rule of thumb for zero padding in image processing?

I see there are a lot of answers on why zero padding is necessary and how it avoids wrapping around the sides of images. However is there a rule of thumb on how much padding will be good for the image ...
8
votes
1answer
2k views

How to remove reflections from images?

I've been playing around with making images better and removing all the unwanted disturbances from it. I found out a major concern would be removing the unwanted reflections that might come. I've ...
0
votes
1answer
26 views

Why does the Y component in YCbCr represent luma/intensity?

As far as I know, the RGB to YCbCr conversion is just a linear transformation, yet the Y channel successfully captures the intensity value of each pixel. How? In other words, where do the following ...
2
votes
0answers
268 views

How do 2D DCT basis functions interact to produce 8x8 JPEG tiles?

This section is a bit of an intro. If you want to skip directly to where the problem is explicitly outlined, skip to the bottom of this post. Please note that I'm not hip with mathematical lingo, so ...
3
votes
1answer
1k views

What is the Difference between Texture and Image?

I am beginner in the image processing I want to know what is difference between Texture and Image? or whether they are same? can anyone explain it. Also,if i want to do texture segmentation,can i ...
0
votes
0answers
29 views

Elimination of image blurring using noise model restoration techniques

How can the blurring be eliminated from image using the noise model restoration process techniques? To my knowledge the answer must be filter.If yes,then which filter is used?
0
votes
1answer
259 views

What is the difference between domain and range filtering?

In the context of image processing, I have heard the expressions "domain filtering" and "range filtering". What do these terms refer to? What is the difference between them?
4
votes
1answer
170 views

Are There Common Values of Standard Deviation for Gaussian Noise of an Image?

For example, it occurs to me that there might be a standard deviation value of Gaussian noise in which the human eye could no longer distinguish an object because the standard deviation is very high ...
5
votes
5answers
11k views

What is Hue and Saturation?

I have difficulty in understanding what is Hue and Saturation. please explain what is hue and saturation to me with an example or analogy.
1
vote
1answer
139 views

How to Detect a Inhomogeneity Region in Image

I have an image that includes object and background. However, the object appears some inhomogeneity region due to illumination. My work is that how to detect inhomogeneity region. Which is feature can ...
1
vote
0answers
28 views

How does phase relate to motions in an image?

There is lots of research based on exaggerating motions by decomposing an image into complex sub-bands using pyramid representations such as the complex steerable pyramid and manipulating phase ...
0
votes
0answers
552 views

Recover Audio from Spectrogram Image

I have applied transformation(Constant Q Transformation) to my audio time domain signal, this gives me Frequency vs Time representation. Now, the CQT values consists of complex values(84*260), but ...
0
votes
1answer
73 views

Why does White Noise in images imply noise in adjacent pixels are independent?

My professor said in the class that for "Additive White noise, the noise in pixels adjacent to each other are independent". How? This is what I have got so far: White noise implies that PSD (Power ...
1
vote
1answer
27 views

Feature normalization (scaling) for Hyperspectral images

have been straggling with the concept of feature normalization for the hyperspectral images. Respect to my problem I have attached a picture of my problem which clearly stands the issue which I have.
0
votes
0answers
42 views

Filter a picture by its color spectrum

I want to split an image in half and remove all colors from one half which aren't present in the other half. I already converted the image from RGB to YCBCR but I'm not sure (from a theoretical ...
3
votes
1answer
2k views

Performing DFT twice on an image. Why am I getting an inverted image? [duplicate]

I was asked to perform DFT on an image twice as a part of my school assignment. Why am I getting a blurry inverted image when I perform DFT on an image twice? Sorry, I'm new to image processing and ...
2
votes
0answers
68 views

What filters are used in this picture?

What filters are used to get an image like one on the left? I need to find the body pose of a person in a picture.
2
votes
0answers
519 views

How do piecewise affine transformation work?

How can piecewise affine transform be used to warp an arbitrary collection of input landmark coordinates to a corresponding set of base coordinates? Can anyone give any physical examples, the book I ...
1
vote
1answer
43 views

Zoom an image with respect to a given image

I posted this question in stack overflow, but I think it is more appropriate here: I have a reference image - 'image_01.png' of size 200x200 and resolution 72 px/in. I have another image 'image_02....
-1
votes
1answer
334 views

How to increase the sharpness of the image using convolution matrix?

I am using 3 X 3 convolution matrix to obtain an sharpness image. But the output result obtain from the above matrix is not much sharpen image. How to increase the sharpness of the image ? Ya i am ...
6
votes
3answers
3k views

What is the difference between MSE and PSNR of images?

I have some doubts. What is the difference between quality parameters MSE and PSNR? Which is used when? Is there any advantage of PSNR over MSE or vice versa? Also I have heard people saying that ...
0
votes
0answers
3k views

Image Processing/Analysis for Eye blink detection

I am working on a eye blink detection project in Matlab. By this moment I have been successfully extracted the images of pupil of eye from the real time video captured via a web cam. But I am stuck ...
-1
votes
1answer
52 views

When does a color channel such as RGB carry more info than a grayscale channel or image?

Typically a gray-scale image gives us more information about an image in terms of a signal processing problem. But when does a color channel carry more info than a gray-scale channel? I understand ...
5
votes
1answer
277 views

Does every 8 by 8 DCT matrix have a valid (in range) IDCT?

For a given quantization level of JPEG compression, are all possible DCT matrices have valid IDCTs. By valid, I mean matrices whose elements are in the range [0,255] ?
2
votes
1answer
1k views

Difference between texture and illumination in image

I am new in image processing. What are texture and illumination in image? How can we define these terms?
1
vote
0answers
35 views

What should I know about Morphological processing [duplicate]

i'm studying my first year as technical student , and we are studying image processing, so last week we got delivered a topic to work on : Morphological processing /opening , i'm trying to dig deeper ...
-2
votes
2answers
173 views

Image processing - Why is sum of values of a blurring filter = 1?

Usually, blurring filters have the sum of all the values in the filter matrix equal to $1$. Why is it so?
0
votes
1answer
759 views

How can I trace a path around an image consisting of only black and white lines?

I'm looking for a way to trace a closed curve (i.e. a long list of pixel values all connected by lines in between) that approximates a bitmap image of black and white lines. The image starts out as ...
1
vote
1answer
1k views

What do the L, M and S pixel values in the LMS color space stand for exactly?

From what I read in the literature, the LMS color space is an attempt to quantify how the human retina's cone cells respond to light. More specifically, L has to deal with long wavelengths, M with ...
1
vote
0answers
37 views

“Image Processing” [closed]

I'm an Italian student. I'm studying Gnu Radio and I would like to upload a photo, can I upload it with "file image source" or other blocks? I need to make FFT of an a image. -> image 2D Thank you ...
0
votes
1answer
204 views

Edge detection in a crack pattern image

Here's an image of a cracked pattern. I wish to convert it to binary image where the continuous crack lines form the only discernible pixels. The main problems I am having in the lack of uniform ...
3
votes
5answers
5k views

What Is the Difference Between the Terms Color Intensity and Color Saturation?

In Digital Image Processing, what is the difference between the intensity and the saturation of a color? How would you explain the difference to a newbie?
1
vote
3answers
223 views

Ship detection from aerial image

I have an aerial image, like this I want to detect the outline of the ship without shadow. How can I do it? I tried threshold in both graylevel, RGB and HSV. It doesn't work perfectly.
0
votes
2answers
5k views

Does the cv2.waitKey argument determine the frame-rate while capturing a video?

Kinda new to image processing, so pardon me if the question is too stupid. Using the library cv2 in python to capture video from my webcam, which, so far as I can see as a programmer, is basically ...
0
votes
2answers
244 views

Selective image compression?

Forgive me if this is the wrong site for this question. Here's my problem: I am creating a game where players have to search for a hidden detail within the overall image. I downloaded an 11MB ...
1
vote
1answer
44 views

How many moments are needed for a discrete distributions

I am doing a project on imaging and I have a more general question about imaging. In general we use the moments of the distribution of the object imaged, because the capture information about the ...
1
vote
0answers
19 views

Can an untilted perspective of an object be obtained from a 2D image of a tilted object using angular transformations?

I'm trying to make a height estimation algorithm that works in tandem with a bounding box object detector. The object detector can recognise the objects in images taken at pitch/yaw angular offsets. ...
1
vote
3answers
1k views

How to determine if a pixel is inside a contour?

I have following picture which I extract the contour from. The contour looks like following I am wondering, for any pixel in the image, how do I determine if it is inside the contour or not? Say "...
2
votes
1answer
415 views

compression ratio of pixels block

I am new to image compression topic and really appreciate it if someone could help me understand how compression rati works in this case. Assuming I have JPEG lossless coder that encodes the following ...
1
vote
1answer
1k views

How Could One Imitate Photoshop's Vibrance Filter with OpenCV?

Can somebody please explain how Photoshop vibrance function can use in opencv c++ ? so that I may reproduce the same effects in my application. Here is the vibrance ...

1 2
3
4 5
10