I want to rotate an image in frequency domain. Inspired in the answers in Image rotation and scaling the frequency domain? I managed to rotate square images. (See the following python script using OpenCV)
M = cv2.imread("lenna.png")
M=np.float32(M)
hanning=cv2.createHanningWindow((M.shape[1],M.shape[0]),cv2.CV_32F)
M=hanning*M
sM = fftshift(M)
rotation_center=(M.shape[1]/2,M.shape[0]/2)
rot_matrix=cv2.getRotationMatrix2D(rotation_center,angle,1.0)
FsM = fftshift(cv2.dft(sM,flags = cv2.DFT_COMPLEX_OUTPUT))
rFsM=cv2.warpAffine(FsM,rot_matrix,(FsM.shape[1],FsM.shape[0]),flags=cv2.INTER_LINEAR, borderMode=cv2.BORDER_CONSTANT)
IrFsM = ifftshift(cv2.idft(ifftshift(rFsM),flags=cv2.DFT_REAL_OUTPUT))
This works fine with squared images. (Better results could be achieved by padding the image)
However, when only using a non-squared portion of the image, the rotation in frequency domain shows some kind of shearing effect.
Any idea on how to achieve this? Obivously I could pad the image to make it square, however the final purpose of all this is to rotate FFTs as fast as possible for an iterative image registration algorithm and this would slightly slow down the algorithm.
Following the suggestion of #CrisLuengo I found the affine transform needed to avoid padding the image. Obviously it will depend on the image size and the application but for my case avoidding the padding is very interesting.
The modified script looks now like:
#rot_matrix=cv2.getRotationMatrix2D(rotation_center,angle,1.0)
kx=1.0
ky=1.0
if(M.shape[0]>M.shape[1]):
kx= float(M.shape[0]) / M.shape[1]
else:
ky=float(M.shape[1])/M.shape[0]
affine_transform = np.zeros([2, 3])
affine_transform[0, 0] = np.cos(angle)
affine_transform[0, 1] = np.sin(angle)*ky/kx
affine_transform[0, 2] = (1-np.cos(angle))*rotation_center[0]-ky/kx*np.sin(angle)*rotation_center[1]
affine_transform[1, 0] = -np.sin(angle)*kx/ky
affine_transform[1, 1] = np.cos(angle)
affine_transform[1, 2] = kx/ky*np.sin(angle)*rotation_center[0]+(1-np.cos(angle))*rotation_center[1]
FsM = fftshift(cv2.dft(sM,flags = cv2.DFT_COMPLEX_OUTPUT))
rFsM=cv2.warpAffine(FsM,affine_transform, (FsM.shape[1],FsM.shape[0]),flags=cv2.INTER_LINEAR, borderMode=cv2.BORDER_CONSTANT)
IrFsM = ifftshift(cv2.idft(ifftshift(rFsM),flags=cv2.DFT_REAL_OUTPUT))
Where should I start? I can see plenty of face recognition and analysis using Python, Java script but how about Processing ?
I want to determine the distance by using 2 points between upper and lower lip at their highest and lowest point via webcam to use it in further project.
any help would be appreciated
If you want to do it in Processing alone you can use Greg Borenstein's OpenCV for Processing library:
You can start with the Face Detection example
Once you detect a face, you can detect a mouth within the face rectangle using OpenCV.CASCADE_MOUTH.
Once you have mouth detected maybe you can get away with using the mouth bounding box height. For more detail you use OpenCV to threshold that rectangle. Hopefully the open mouth will segment nicely from the rest of the skin. Finding contours should give you lists of points you can work with.
For something a lot more exact, you can use Jason Saragih's CLM FaceTracker, which is available as an OpenFrameworks addon. OpenFrameworks has similarities to Processing. If you do need this sort of accuracy in Processing you can run FaceOSC in the background and read the mouth coordinates in Processing using oscP5
Update
For the first option, using HAAR cascade classifiers, turns out there are a couple of issues:
The OpenCV Processing library can load one cascade and a second instance will override the first.
The OpenCV.CASCADE_MOUTH seems to work better for closed mouths, but not very well with open mouths
To get past the 1st issue, you can use the OpenCV Java API directly, bypassing OpenCV Processing for multiple cascade detection.
There are couple of parameters that can help the detection, such as having idea of the bounding box of the mouth before hand to pass as a hint to the classifier.
I've done a basic test using a webcam on my laptop and measure the bounding box for face and mouth at various distances. Here's an example:
import gab.opencv.*;
import org.opencv.core.*;
import org.opencv.objdetect.*;
import processing.video.*;
Capture video;
OpenCV opencv;
CascadeClassifier faceDetector,mouthDetector;
MatOfRect faceDetections,mouthDetections;
//cascade detections parameters - explanations from Mastering OpenCV with Practical Computer Vision Projects
int flags = Objdetect.CASCADE_FIND_BIGGEST_OBJECT;
// Smallest object size.
Size minFeatureSizeFace = new Size(50,60);
Size maxFeatureSizeFace = new Size(125,150);
Size minFeatureSizeMouth = new Size(30,10);
Size maxFeatureSizeMouth = new Size(120,60);
// How detailed should the search be. Must be larger than 1.0.
float searchScaleFactor = 1.1f;
// How much the detections should be filtered out. This should depend on how bad false detections are to your system.
// minNeighbors=2 means lots of good+bad detections, and minNeighbors=6 means only good detections are given but some are missed.
int minNeighbors = 4;
//laptop webcam face rectangle
//far, small scale, ~50,60px
//typing distance, ~83,91px
//really close, ~125,150
//laptop webcam mouth rectangle
//far, small scale, ~30,10
//typing distance, ~50,25px
//really close, ~120,60
int mouthHeightHistory = 30;
int[] mouthHeights = new int[mouthHeightHistory];
void setup() {
opencv = new OpenCV(this,320,240);
size(opencv.width, opencv.height);
noFill();
frameRate(30);
video = new Capture(this,width,height);
video.start();
faceDetector = new CascadeClassifier(dataPath("haarcascade_frontalface_alt2.xml"));
mouthDetector = new CascadeClassifier(dataPath("haarcascade_mcs_mouth.xml"));
}
void draw() {
//feed cam image to OpenCV, it turns it to grayscale
opencv.loadImage(video);
opencv.equalizeHistogram();
image(opencv.getOutput(), 0, 0 );
//detect face using raw Java OpenCV API
Mat equalizedImg = opencv.getGray();
faceDetections = new MatOfRect();
faceDetector.detectMultiScale(equalizedImg, faceDetections, searchScaleFactor, minNeighbors, flags, minFeatureSizeFace, maxFeatureSizeFace);
Rect[] faceDetectionResults = faceDetections.toArray();
int faces = faceDetectionResults.length;
text("detected faces: "+faces,5,15);
if(faces >= 1){
Rect face = faceDetectionResults[0];
stroke(0,192,0);
rect(face.x,face.y,face.width,face.height);
//detect mouth - only within face rectangle, not the whole frame
Rect faceLower = face.clone();
faceLower.height = (int) (face.height * 0.65);
faceLower.y = face.y + faceLower.height;
Mat faceROI = equalizedImg.submat(faceLower);
//debug view of ROI
PImage faceImg = createImage(faceLower.width,faceLower.height,RGB);
opencv.toPImage(faceROI,faceImg);
image(faceImg,width-faceImg.width,0);
mouthDetections = new MatOfRect();
mouthDetector.detectMultiScale(faceROI, mouthDetections, searchScaleFactor, minNeighbors, flags, minFeatureSizeMouth, maxFeatureSizeMouth);
Rect[] mouthDetectionResults = mouthDetections.toArray();
int mouths = mouthDetectionResults.length;
text("detected mouths: "+mouths,5,25);
if(mouths >= 1){
Rect mouth = mouthDetectionResults[0];
stroke(192,0,0);
rect(faceLower.x + mouth.x,faceLower.y + mouth.y,mouth.width,mouth.height);
text("mouth height:"+mouth.height+"~px",5,35);
updateAndPlotMouthHistory(mouth.height);
}
}
}
void updateAndPlotMouthHistory(int newHeight){
//shift older values by 1
for(int i = mouthHeightHistory-1; i > 0; i--){
mouthHeights[i] = mouthHeights[i-1];
}
//add new value at the front
mouthHeights[0] = newHeight;
//plot
float graphWidth = 100.0;
float elementWidth = graphWidth / mouthHeightHistory;
for(int i = 0; i < mouthHeightHistory; i++){
rect(elementWidth * i,45,elementWidth,mouthHeights[i]);
}
}
void captureEvent(Capture c) {
c.read();
}
One very imortant note to make: I've copied cascade xml files from the OpenCV Processing library folder (~/Documents/Processing/libraries/opencv_processing/library/cascade-files) to the sketch's data folder. My sketch is OpenCVMouthOpen, so the folder structure looks like this:
OpenCVMouthOpen
├── OpenCVMouthOpen.pde
└── data
├── haarcascade_frontalface_alt.xml
├── haarcascade_frontalface_alt2.xml
├── haarcascade_frontalface_alt_tree.xml
├── haarcascade_frontalface_default.xml
├── haarcascade_mcs_mouth.xml
└── lbpcascade_frontalface.xml
If you don't copy the cascades files and use the code as it is you won't get any errors, but the detection simply won't work. If you want to check, you can do
println(faceDetector.empty())
at the end of the setup() function and if you get false, the cascade has been loaded and if you get true, the cascade hasn't been loaded.
You may need to play with the minFeatureSize and maxFeatureSize values for face and mouth for your setup. The second issue, cascade not detecting wide open mouth very well is tricky. There might be an already trained cascade for open mouths, but you'd need to find it. Otherwise, with this method you may need to train one yourself and that can be a bit tedious.
Nevertheless, notice that there is an upside down plot drawn on the left when a mouth is detected. In my tests I noticed that the height isn't super accurate, but there are noticeable changes in the graph. You may not be able to get a steady mouth height, but by comparing current to averaged previous height values you should see some peaks (values going from positive to negative or vice-versa) which give you an idea of a mouth open/close change.
Although searching through the whole image for a mouth as opposed to a face only can be a bit slower and less accurate, it's a simpler setup. It you can get away with less accuracy and more false positives on your project this could be simpler:
import gab.opencv.*;
import java.awt.Rectangle;
import org.opencv.objdetect.Objdetect;
import processing.video.*;
Capture video;
OpenCV opencv;
Rectangle[] faces,mouths;
//cascade detections parameters - explanations from Mastering OpenCV with Practical Computer Vision Projects
int flags = Objdetect.CASCADE_FIND_BIGGEST_OBJECT;
// Smallest object size.
int minFeatureSize = 20;
int maxFeatureSize = 150;
// How detailed should the search be. Must be larger than 1.0.
float searchScaleFactor = 1.1f;
// How much the detections should be filtered out. This should depend on how bad false detections are to your system.
// minNeighbors=2 means lots of good+bad detections, and minNeighbors=6 means only good detections are given but some are missed.
int minNeighbors = 6;
void setup() {
size(320, 240);
noFill();
stroke(0, 192, 0);
strokeWeight(3);
video = new Capture(this,width,height);
video.start();
opencv = new OpenCV(this,320,240);
opencv.loadCascade(OpenCV.CASCADE_MOUTH);
}
void draw() {
//feed cam image to OpenCV, it turns it to grayscale
opencv.loadImage(video);
opencv.equalizeHistogram();
image(opencv.getOutput(), 0, 0 );
Rectangle[] mouths = opencv.detect(searchScaleFactor,minNeighbors,flags,minFeatureSize, maxFeatureSize);
for (int i = 0; i < mouths.length; i++) {
text(mouths[i].x + "," + mouths[i].y + "," + mouths[i].width + "," + mouths[i].height,mouths[i].x, mouths[i].y);
rect(mouths[i].x, mouths[i].y, mouths[i].width, mouths[i].height);
}
}
void captureEvent(Capture c) {
c.read();
}
I was mentioning segmenting/thresholding as well. Here's a rough example using the lower part of a detected face just a basic threshold, then some basic morphological filters (erode/dilate) to cleanup the thresholded image a bit:
import gab.opencv.*;
import org.opencv.core.*;
import org.opencv.objdetect.*;
import org.opencv.imgproc.Imgproc;
import java.awt.Rectangle;
import java.util.*;
import processing.video.*;
Capture video;
OpenCV opencv;
CascadeClassifier faceDetector,mouthDetector;
MatOfRect faceDetections,mouthDetections;
//cascade detections parameters - explanations from Mastering OpenCV with Practical Computer Vision Projects
int flags = Objdetect.CASCADE_FIND_BIGGEST_OBJECT;
// Smallest object size.
Size minFeatureSizeFace = new Size(50,60);
Size maxFeatureSizeFace = new Size(125,150);
// How detailed should the search be. Must be larger than 1.0.
float searchScaleFactor = 1.1f;
// How much the detections should be filtered out. This should depend on how bad false detections are to your system.
// minNeighbors=2 means lots of good+bad detections, and minNeighbors=6 means only good detections are given but some are missed.
int minNeighbors = 4;
//laptop webcam face rectangle
//far, small scale, ~50,60px
//typing distance, ~83,91px
//really close, ~125,150
float threshold = 160;
int erodeAmt = 1;
int dilateAmt = 5;
void setup() {
opencv = new OpenCV(this,320,240);
size(opencv.width, opencv.height);
noFill();
video = new Capture(this,width,height);
video.start();
faceDetector = new CascadeClassifier(dataPath("haarcascade_frontalface_alt2.xml"));
mouthDetector = new CascadeClassifier(dataPath("haarcascade_mcs_mouth.xml"));
}
void draw() {
//feed cam image to OpenCV, it turns it to grayscale
opencv.loadImage(video);
opencv.equalizeHistogram();
image(opencv.getOutput(), 0, 0 );
//detect face using raw Java OpenCV API
Mat equalizedImg = opencv.getGray();
faceDetections = new MatOfRect();
faceDetector.detectMultiScale(equalizedImg, faceDetections, searchScaleFactor, minNeighbors, flags, minFeatureSizeFace, maxFeatureSizeFace);
Rect[] faceDetectionResults = faceDetections.toArray();
int faces = faceDetectionResults.length;
text("detected faces: "+faces,5,15);
if(faces > 0){
Rect face = faceDetectionResults[0];
stroke(0,192,0);
rect(face.x,face.y,face.width,face.height);
//detect mouth - only within face rectangle, not the whole frame
Rect faceLower = face.clone();
faceLower.height = (int) (face.height * 0.55);
faceLower.y = face.y + faceLower.height;
//submat grabs a portion of the image (submatrix) = our region of interest (ROI)
Mat faceROI = equalizedImg.submat(faceLower);
Mat faceROIThresh = faceROI.clone();
//threshold
Imgproc.threshold(faceROI, faceROIThresh, threshold, width, Imgproc.THRESH_BINARY_INV);
Imgproc.erode(faceROIThresh, faceROIThresh, new Mat(), new Point(-1,-1), erodeAmt);
Imgproc.dilate(faceROIThresh, faceROIThresh, new Mat(), new Point(-1,-1), dilateAmt);
//find contours
Mat faceContours = faceROIThresh.clone();
List<MatOfPoint> contours = new ArrayList<MatOfPoint>();
Imgproc.findContours(faceContours, contours, new Mat(), Imgproc.RETR_EXTERNAL , Imgproc.CHAIN_APPROX_SIMPLE);
//draw contours
for(int i = 0 ; i < contours.size(); i++){
MatOfPoint contour = contours.get(i);
Point[] points = contour.toArray();
stroke(map(i,0,contours.size()-1,32,255),0,0);
beginShape();
for(Point p : points){
vertex((float)p.x,(float)p.y);
}
endShape();
}
//debug view of ROI
PImage faceImg = createImage(faceLower.width,faceLower.height,RGB);
opencv.toPImage(faceROIThresh,faceImg);
image(faceImg,width-faceImg.width,0);
}
text("Drag mouseX to control threshold: " + threshold+
"\nHold 'e' and drag mouseX to control erodeAmt: " + erodeAmt+
"\nHold 'd' and drag mouseX to control dilateAmt: " + dilateAmt,5,210);
}
void mouseDragged(){
if(keyPressed){
if(key == 'e') erodeAmt = (int)map(mouseX,0,width,1,6);
if(key == 'd') dilateAmt = (int)map(mouseX,0,width,1,10);
}else{
threshold = mouseX;
}
}
void captureEvent(Capture c) {
c.read();
}
This could be improved a bit by using YCrCb colour space to segment skin better, but overall you notice that there are quite a few variables to get right which doesn't make this a very flexible setup.
You will be much better results using FaceOSC and reading the values you need in Processing via oscP5. Here is a slightly simplified version of the FaceOSCReceiver Processing example focusing mainly on mouth:
import oscP5.*;
OscP5 oscP5;
// num faces found
int found;
// pose
float poseScale;
PVector posePosition = new PVector();
// gesture
float mouthHeight;
float mouthWidth;
void setup() {
size(640, 480);
frameRate(30);
oscP5 = new OscP5(this, 8338);
oscP5.plug(this, "found", "/found");
oscP5.plug(this, "poseScale", "/pose/scale");
oscP5.plug(this, "posePosition", "/pose/position");
oscP5.plug(this, "mouthWidthReceived", "/gesture/mouth/width");
oscP5.plug(this, "mouthHeightReceived", "/gesture/mouth/height");
}
void draw() {
background(255);
stroke(0);
if(found > 0) {
translate(posePosition.x, posePosition.y);
scale(poseScale);
noFill();
ellipse(0, 20, mouthWidth* 3, mouthHeight * 3);
}
}
// OSC CALLBACK FUNCTIONS
public void found(int i) {
println("found: " + i);
found = i;
}
public void poseScale(float s) {
println("scale: " + s);
poseScale = s;
}
public void posePosition(float x, float y) {
println("pose position\tX: " + x + " Y: " + y );
posePosition.set(x, y, 0);
}
public void mouthWidthReceived(float w) {
println("mouth Width: " + w);
mouthWidth = w;
}
public void mouthHeightReceived(float h) {
println("mouth height: " + h);
mouthHeight = h;
}
// all other OSC messages end up here
void oscEvent(OscMessage m) {
if(m.isPlugged() == false) {
println("UNPLUGGED: " + m);
}
}
On OSX you can simply download the compiled FaceOSC app.
On other operating systems you may need to setup OpenFrameworks, download ofxFaceTracker and compile FaceOSC yourself.
It's really hard to answer general "how do I do this" type questions. Stack Overflow is designed for specific "I tried X, expected Y, but got Z instead" type questions. But I'll try to answer in a general sense:
You need to break your problem down into smaller pieces.
Step 1: Can you get a webcam feed showing in your sketch? Don't worry about the computer vision stuff for a second. Just get the camera connected. Do some research and try something out.
Step 2: Can you detect facial features in that video? You might try doing it yourself, or you might use one of the many libraries listed in the Videos and Vision section of the Processing libraries page.
Step 3: Read the documentation on those libraries. Try them out. You might have to make a bunch of little example sketches using each library until you find one you like. We can't do this for you, as which one is right for you depends on you. If you're confused about something specific we can try to help you, but we can't really help you with picking out a library.
Step 4: Once you've done a bunch of example programs and picked out a library, start working towards your goal. Can you detect facial features using the library? Get just that part working. Once you have that working, can you detect changes like opening or closing a mouth?
Work on one small step at a time. If you get stuck, post an MCVE along with a specific technical question, and we'll go from there. Good luck.
What I am doing is trying to implement an Skin Probability Maps algorithm for skin detection in OpenCV.
I've stuck in a place where I should compare SkinHistValue / NonSkinHistValue probability of each pixel with Theta threshold according to http://www.cse.unsw.edu.au/~icml2002/workshops/MLCV02/MLCV02-Morales.pdf and this tutorial http://www.morethantechnical.com/2013/03/05/skin-detection-with-probability-maps-and-elliptical-boundaries-opencv-wcode/
My problems lies in calculating the coords for hist value:
From the tutorial:
calcHist(&nRGB_frame,1,channels,mask,skin_Histogram,2,histSize,ranges,uniform,accumulate);
calcHist(&nRGB_frame,1,channels,~mask,non_skin_Histogram,2,histSize,ranges,uniform,accumulate);
Calculates the histograms. Than i normalize them.
And after that:
for (int i=0; i<nrgb.rows; i++) {
int gbin = cvRound((nrgb(i)[1] - 0)/range_dist[0] * hist_bins[0]);
int rbin = cvRound((nrgb(i)[2] - low_range[1])/range_dist[1] * hist_bins[1]);
float skin_hist_val = skin_Histogram.at<float>(gbin,rbin);
};
Where nrgb is my image, and im trying to get skin_hist_value for that. But the gbin and rbin are probably calculated wrong and it throws an exception (i run outside of array?) when it comes to
skin_Histogram.at<float>(gbin,rbin);
I have totally no idea how to calculate it correctly. Any help?
I am a newbie to openCV. I have installed the opencv library on a ubuntu system, compiled it and trying to look into some image/video processing apps in opencv to understand more.
I am interested to know if OpenCV library has any algorithm/class for removal flicker in captured videos? If yes what document or code should I should look deeper into?
If openCV does not have it, are there any standard implementations in some other Video processing library/SDK/Matlab,.. which provide algorithms for flicker removal from video sequences?
Any pointers would be useful
Thank you.
-AD.
I don't know any standard way to deflicker a video.
But VirtualDub is a Video Processing software which has a Filter for deflickering the video. You can find it's filter source and documents (algorithm description probably) here.
I wrote my own Deflicker C++ function. here it is. You can cut and paste this code as is - no headers needed other than the usual openCV ones.
Mat deflicker(Mat,int);
Mat prevdeflicker;
Mat deflicker(Mat Mat1,int strengthcutoff = 20){ //deflicker - compares each pixel of the frame to a previously stored frame, and throttle small changes in pixels (flicker)
if (prevdeflicker.rows){//check if we stored a previous frame of this name.//if not, theres nothing we can do. clone and exit
int i,j;
uchar* p;
uchar* prevp;
for( i = 0; i < Mat1.rows; ++i)
{
p = Mat1.ptr<uchar>(i);
prevp = prevdeflicker.ptr<uchar>(i);
for ( j = 0; j < Mat1.cols; ++j){
Scalar previntensity = prevp[j];
Scalar intensity = p[j];
int strength = abs(intensity.val[0] - previntensity.val[0]);
if(strength < strengthcutoff){ //the strength of the stimulus must be greater than a certain point, else we do not want to allow the change
//value 25 works good for medium+ light. anything higher creates too much blur around moving objects.
//in low light however this makes it worse, since low light seems to increase contrasts in flicker - some flickers go from 0 to 255 and back. :(
//I need to write a way to track large group movements vs small pixels, and only filter out the small pixel stuff. maybe blur first?
if(intensity.val[0] > previntensity.val[0]){ // use the previous frames value. Change it by +1 - slow enough to not be noticable flicker
p[j] = previntensity.val[0] + 1;
}else{
p[j] = previntensity.val[0] - 1;
}
}
}
}//end for
}
prevdeflicker = Mat1.clone();//clone the current one as the old one.
return Mat1;
}
Call it as: Mat= deflicker(Mat). It needs a loop, and a greyscale image, like so:
for(;;){
cap >> frame; // get a new frame from camera
cvtColor( frame, src_grey, CV_RGB2GRAY ); //convert to greyscale - simplifies everything
src_grey = deflicker(src_grey); // this is the function call
imshow("grey video", src_grey);
if(waitKey(30) >= 0) break;
}